Friend In Calgary With Vf1000F Needs Assistance

[zoomzoom]

Hey to all out their in VFR land. I have a friend named Doug in Calgary who is having some issues getting a 1985 VF1000F running. He has owned the bike for over 8 years (I think or maybe more) and from the sounds of it the carbs are plugged with old fuel. The VF in question is my old bike which I gave to him as a gift but he has not had the opportunity to ride it very much in the last few years so it sat stored in his garage.

He used to go out and start it to let it run for a bit every few months to prevent the fuel from gelling in the carbs but I think he forgot to add stabilizer to the fuel and drain the floats the last time he used it. Doug assumed the carbs were varnished and have old fuel gumming them up so he removed them to clean them but now he is a little, well, in over his head from the sounds of it and was wondering if I could help him with the problem. I have no experience with changing or cleaning carbs and was wondering if there is anyone from the forum in Calgary who might be willing and able to give him a hand getting the bike running. Doug has owned many bikes in the past but has been away from biking, if you will, for about 15 or more years and has lots of experience with doing mechanical work to his own vehicles but the carb thing, according to him is just a little bit too daunting.

Normally I would suggest that Doug logs on to the site himself and asks for assistance from the vast membership here, but he would be the first to admit that if there are few things he finds problematic to deal with, but his lack of skills with a computer are one of them. Plus which I think he a bit embarrased to ask for help.

If anyone out there in Calgary (or the surrounding area) might be willing to possibly give him a hand getting the old girl running again or could help point him the right direction, I'm sure he would be eternally grateful. Doug has been a friend for over 30 years and I could not ask for a better person as a friend so he is certainly good people.

If you can help, please shoot me a PM and I will try to get Doug in touch with you.

Thanks for the help

Bill

[tomk1960]

You should try contacting Mike Nixon throught his web site, www.motorcycleproject.com Mike has a how-to booklet for overhauling these carbs. If you think it's a bit too much to handle, you can send him the carbs and he'll overhaul them for you for a reasonable price. I had him do my VF1000F carbs and he did an outstanding job. The bike fired right up and ran great after he did his magic. The bench sync he performed brought them in better than spec, too.

Best of luck.

[zoomzoom]

Thanks very much for the information Tomk, I will check out the site. The help is greatly appreciated.

[Grilldemon]

I'm not far away in Penhold (just south of Red Deer) and own the same bike. Done my carbs, a nasty job to get them off, but once you get them set up give no trouble (typical Honda) I also have a Carbtune sync tool. He can get a hold of me through here if he would like some assistance. More than willing to help a fellow VFR rider.

[gll429]

for your pal...

hiya!

i will start with i am a honda tech..and i have had lots of VFRs since my 16th bday.. :)
step one..DOWNLOAD THE MANUAL

if you bike has been sitting with gas in the carbs..
YOU'RE GOING SHOPPING NOW!!!
30 bucks.. a one gallon can of GUNK CARB DIP.. this is NOT spray. gunk is the brand.
DO NOT GET BERRYMAN DIP!!
it SUCKS SUCKS SUCKS!!!!!!!!
did i mention berryman brand sucks??

$4 a spray bottle of silicone lube.
$4 a spray can of carb cleaner..
if you have an air compresser.. that would be great.

$15 get 2 cheap pry bars about footlong and a big rubber mallet.

$1 each get several aluminium foil baking pans 1x1 or about that.
$1 plastic pan the size of a kittylitter tray.
$1 a small flat blade screw driver that will be used to get out the pilot jets.. which i can promise you are clogged up. the same size as the pocket drivers the snap-on guts give out. and you should already have a 6 , 7, 8,10 12, 13, 14, 17 18, 19 sockets.. you will only need the 7mm here.

$7 a cheap impact driver.. the floatbowl screws may be 'screwed" if others screwed them up.
$5 a hammer.


first up.. you all ready have the tank off.. and the air box.. leave the 4 carbs connected!!there is no reason to separate them from the plenum .

next.. unscrew the 2 screws holding the throttle cable clamp in place to the carb... and you remove the cable in 30 seconds.

since you have the airbox off.. you can how the choke cable come off.. use your finger to slide the choke.. and pull the slack cable out .and remove if from the carb.
loosen the front top clamps on the intake boots..and REMOVE the rear 2

place the 2 pry bars under the rear carbs. right where they meet the rear head.. and gently pry them up both at the same time. bet they pop up in 5 seconds. if they dont.. make sure you loosened the clamps.. once removed..

now that the carbs are out..
remove the float bowls. and the jets..
remove the carb tops and the springs and slides..

place the cabs in the foil bottom side down. and shape the foil to get a good fit.. place in another foil pan.. just incase the 1st will leak.. and repeat..
you will now place this in the kitty litter plastic tray.
pour the gunk carb dip into the foil and let the carbs soak.. drop your jets in there too.. and in a few hours go check them.. if the brass looks like new..and you can see through all of the jet holes. you're ready to rinse it all off.
you MUST rinse it with water until the run off stops turning white.!!!!
let dry.. or blow it off.
blow out all the holes in the carb with air compresser.. or carb spray.


reinstall the jets and floats and float bowls, ditto for the slides and tops.
lube all pivots with silicone spray..lube all choke slides ect etc..
lube the intake boots..
install the front 2 carbs FIRST! they will pop right in. next..
lower the rear 2 and then place the pry bar tips just inside the lip.. press down on the carbs.. the prybars will act like a shoe horn and presto! your in! ! if not..you may need the rubber mallot to drive the carbs down. install the top clamps and all the other stuff.

honestly.. i can never understand why people complain about installing and removing the carbs. my 1st try took 5 min off and 5 min on. that was 25 years ago.. my god i am getting old!

[zoomzoom]

I'm not far away in Penhold (just south of Red Deer) and own the same bike. Done my carbs, a nasty job to get them off, but once you get them set up give no trouble (typical Honda) I also have a Carbtune sync tool. He can get a hold of me through here if he would like some assistance. More than willing to help a fellow VFR rider.

Hey Grilldemon

I'm certain Doug would be happy to chat with you about the bike, and see if there is anything you could help with.

[JeffInFranklinTN]

An FYI for all of you carbureted V4's. There is a man named Billy Carr in Canton, TX. who has made himself one hell of a good reputation rebuilding these carbs.

I know there are many folks here who can do this themselves BUT if you feel you don't have the knowledge to do it yourself contact Billy.

Billy Carr

20706 State Highway 19

Canton, TX 75103

Via phone..

903-567-1543

or via email..

billycarrjr@earthlink.net

[Kel]

Carbs are not difficult at all, just be organized. To do a good carb clean. Have him read this...really should be a sticky in here.


***DO NOT remove the aluminum plate that holds the 4 carbs together. You can do a pretty good job of cleaning without separating the carbs. The guide shows them completely apart but you don't have to get that crazy. When Billy does them, everything does get broken down.***



From V4BBS, for quick reference...
"The V4 engines use 4 constant velocity (variable venturi) carburetors to supply fuel to the engine. The constant velocity refers to the air speed through the throat of the carb. The velocity is controlled by a slide mounted to a diaphram. The diaphram is sensitive to vacuum created by the flow of air across a hole(s) in the needle end of the slide. As the engine speed increases, the vacuum above the diaphram increases due to venturi action and the slide is raised.

There are three circuits (paths) in the carb.
The starting circuit (choke) provides extra fuel when the choke is open. It uses a fixed jet and a choke plunger to control the flow of fuel to the port in the carb throat. The restriction is the fixed jet at about 0.021 inches. The choke plunger also provides an air bypass around the throttle plate to increase the engine speed during warm up.

The low speed circuit provides the primary fuel for operation below 4000 to 5000 rpm. When the engine is pulling vacuum the fuel is drawn through a passage to the low speed needle valve, and then to a large hole on the bowl side of the throat on the engine side of the throttle plate. The needle valve controls flow to the large hole. This path also feeds the 4 tiny holes on the float side of the throat and under the throttle plate. Both paths continue to function at all engine speeds. The restriction is the low speed needle or the low speed jet.

The high speed circuit provides fuel above 4000 rpm. It uses a fixed orifice and a needle connected to the slide to control the flow of fuel to the needle valve opening in the carb throat. As engine speed increases the slide raises the needle and allows additional fuel to flow. The restriction is the needle valve on the slide. Since the needle valve never completely closes, the circuit provides fuel at all engine speeds.

It should be verified that fuel is getting to the carbs. Verify you are getting a flow of fuel at the inlet hose to the carbs. No flow can be caused by delivery problems due to tank venting, plugged screen in the tank, pinched hoses, fuel pump problems or fuel filter plugged. Or you could be out of gas.

The main symptoms of carb trouble are.
1. Hard cold starting that is caused by restricted choke circuit, low speed circuit or improper fuel level in the float bowl. Failure modes that cause this are.
a. Plugged low speed jet. The jet must be removed and cleaned.
b. Plugged choke jet. The jet cannot be removed, it must be cleaned in place.
c. Plugged low speed circuit and choke circuit passages from the jet to the carb throat. The carburetor must be removed and the passages cleaned.
d. Improper fuel level in the float bowl. The float valve and screen must be removed and cleaned. The float must then be set to the correct level.
e. Improper setting of the low speed needle valves. In most cases resetting them to the factory recommendation will be satisfactory.

2. Poor idling and hesitation when accelerating up to 4000 rpm caused by restricted low speed circuits or improper fuel level in the float bowl. . Failure modes that cause this are.
a. Plugged low speed jet. The jet must be removed and cleaned.
b. Plugged low speed circuit passages from the jet to the carb throat. The carburetor must be removed and the passages cleaned.
c. Improper fuel level in the float bowl. The float valve and screen must be removed and cleaned. The float must then be set to the correct level.
d. Improper synchronization of the 4 carburetors. They may synced while on the engine using vacuum gages or mercury sticks.
f. Improper setting of the low speed needle valves. In most cases resetting them to the factory recommendation will be satisfactory.

3. Poor operation above 4000 rpm caused by improper slide operation or improper fuel level in the float bowl. Failure modes that cause this are.
a. Ripped diaphram. Ripped diaphrams must be replaced, usually with the carbs off the bike.
b. Leaking diaphram. If the diaphram is not seated correctly in the cover it will leak air and defeat the vacuum action.
c. Sticking slide. The slide must be removed and any contamination removed.
d. Choke valve not closing completely.
e. Incorrect high speed jet or emulsion tube installed. Verify correct parts.
f. Incorrect spring installed over the slide. Verify correct springs.
g. Incorrect high speed needle installed. Verify correct needle.


Carburetor Cleaning and Rebuild

There are 3 approaches to cleaning the carbs.
Use an additive in the gas tank such as Techtron or Sea Foam.
Do the disassembly and cleaning yourself.
Send them to a professional for a super cleaning.
The additive route sometimes works if the plugging of circuits is not too bad.
The do it yourself method will achieve well functioning carburetors that looks like they did when you took it off.
The professional cleaning by Billy Carr will make them shine and function like new with the added advantage that he has any needed replacement parts. BBS friendly carb cleaning service

To quote Billy, "being the local carb guy means I get mine either way. I rebuild them... I get paid. You do them yourself with my cheap carb kit ... I get paid. Buy the carb kit and in a few hours and you can have a resealed long lasting set of carbs. Never be afraid to delve in to a set of carbs unless you do not possess the simple ability to tell which end of a combination wrench is which. Worst case scenario is you mail me a bucket full of parts when you realize you got in over your head. Saves me teardown time."

Sample of his work.





Helpful hints if you do them yourself.

Take photos of the carbs installed, cable routing, removed still on the plenum from all angles. You will treasure them when you put things back together.
Remove all 4 carburetors and the plenum (air box) as an assembly.
Drain the fuel from each carb through the drain nipple by opening the needle screw in the bottom of the float bowl.
If the carb rack (all 4 carbs bolted to the plenum) is dirty clean it with a degreaser before you start to take things apart.





When you disassemble your carbs keep the parts separated by individual carb as they are different from front to rear in many cases (baby food jars are great). Note, after 30 years and many owners the parts may not actually be in the correct location. Always refer to manual for the correct placement and part. The model number will be stamped on the flange above the float bowl.
Do not be afraid to use a permanent marker in an out of the way spot to keep the carbs straight (number the baby food jars too). They are numbered #1- #4 left to right as you sit on the bike.
If you do not split the rack you will not have to hassle with the linkages and the throttle plate synch will be much easier. You will not be able to change the fuel and air tube o-rings however, your call.
Use a good #3 Philips tip screw driver bit or impact bit to loosen all screws. Tap each one a couple of times with a hammer and bit before you try to loosen them
Your work area should someplace where you can track down parts that may escape you.

Do It Yourself Rebuild

Buy a carb rebuild kit from Billy C at BBS friendly carb cleaning service
It has everything you need plus a DVD filled with information.


One carb at a time, remove the 4 screws that hold the float bowl on. Check condition of the o-ring seal. If hardened, get new ones. If they have never been replaced they will be hard and flat.




Remove and clean the drain plug and clean the drain nipple if plugged.
Remove the pin holding the float in place, remove the float and needle.
Remove and check the condition of the needle seat and screen.
Remove the high speed jet and holder (emulsion tube). Make sure all holes are clean.
Remove the low speed jet. Make sure all holes are clean especially the one through the center, clean with a 0.015 inch wire or #79 pin drill for 38 size jets. The size of the jet is stamped on it. 38 stands for 0.38 mm or about 0.15 inches.
The choke jet cannot be removed, pressed in. Clean the hole through the center of it, clean with an 0.021 inch wire or a #75 pin drill.
Inspect all passages and blow air or a solvent through them. Look into each hole with a good light and a magnifying glass.

Login 20pc Drill Bits #61-80 and Pin Vise





Remove the low speed needle from the side of the carb just above the float joint. It may be covered with an aluminum cap to prevent tampering. If it is, drill a 1/8 inch hole in the cap, drive in a sheet metal screw a couple of threads and pull the cap out. Before unscrewing the needle, turn it in counting the number of rotations until it seats lightly. The needle will have a spring, flat washer and o-ring behind it, remove them.
Inspect all passages with a good light and a magnifying glass and blow air or a solvent through them.






Remove the choke valve by removing the black plastic nut, the linkage plate, the black linkage sleeve and spring. Work it out as an assembly. Be careful, the black nut is fragile.
Take some more pictures of where all the linkage goes.




Blow air through all the passages to clean, including the choke jet.

On the other side of the carb, remove 4 screws holding on the chrome cover. Be alert, it is spring loaded.
Remove the diaphram cover and spring.
Remove the diaphram slide assembly. Carefully inspect the diaphram for any tears or cracks. If any found, big and expensive problem to replace. Clean the slide and its bore of any residue. Don't use carb cleaner on the diaphrams, it will damage them. Use a 0.018 inch wire or pin drill #77 to clean the brass orifice located under the diaphram cover. This orifice appears to be a drain for any fuel accumulated in the top of the diaphram.

With all the jets, needles, slides and chokes removed, blow air through all the passages including the choke jet. Blow air through the small ports in the carb throat to verify that they are clear. Soaking in a cleaner may now be done safely.




***THIS IS NOT MANDATORY, I WOULD SKIP THIS UNLESS YOU HAVE FUEL LEAKAGE FROM THE TUBES***

Now is the time to replace the o rings on the fuel rail if you plan on doing it. Be very careful with the tubes as they can be broken with sideways pressure. The o rings are included in the Billy C kit.
Use a quality #3 Philips head screw driver to loosen the 8 screws holding the carbs to the plenum. Tap them with a bit and hammer to break them loose. Leave all screws in place until they all have been broken loose.
Take pictures of all the springs on the throttle linkage.
Remove the 8 screws and remove the plenum. There are locator dowels on each carb that may require prying out for separation. BE CAREFUL the sync and shaft springs will fall out when you separate the carbs. You did take those pictures right? The tubes are unique so keep track of what goes where.
Remove the o rings from the tubes and replace with the new ones.
Clean the holes that the tubes insert into. Did you notice that the fuel path runs straight through the bottom of all 4 carbs?
Carefully insert the fuel tubes back into the carb bodies along with the vent tubes if your model has them. Do not let the o ring roll out of the groove. The throttle adjuster plates and shaft springs must also be lined up for each carb. Do not worry about the sync springs at this point.
Replace the plenum with new socket head cap screws M6-1.00 x 20. You do not want to mess with the Philips the next time. They are available at most hardware stores for about $.50 each. Evenly tighten the screws making sure that the tubes and shafts are not binding. Boiling the air funnels makes them easier to install. Old ones shrink and are a pain in the ass to get in place. Make sure the line on the funnel is between the two index lines on the airbox.

When you are satisfied that everything is clean, begin reassembly.

Assemble the diaphram slide assembly into the carb, make sure the hole(s) in the diaphram align with the holes in the carb.
Assemble the spring and cover. Short vacuum piston springs install in the rear carbs, long springs install in the front carbs. Make sure the diaphram seats into the groove. Tighten 4 screws. To test seating, hook a shop vac up to the engine side of the carb and open the throttle plate. The slide should rise, then fall when the throttle is closed. If it doesn't the diaphram is not seated.





Gently flex the floats to check for cracks. They like to crack where the lattice meets the float---and then they fill up with gas. You'll notice the float full of fuel if you tear down quick after carb removal. Otherwise you won't know without careful inspection.

Inspect your float needles. The rubber tip on can pull out of the metal needle and bind up the valve.

Carefully clean the choke plungers. It makes them operate smoother and prevents them from hanging up. Some fine emery paper works well for this. Inspect the end of the choke valve for the condition of the rubber insert. If it is badly worn in may be removed and flipped over. Replacements are not available.
Assemble the high and low speed jets in the carb tightly. Verify the correct size is used in the correct location. The fuel emulsion tubes that the main jets thread into are different between front and rear carbs. There are low drilled holes and high drilled holes in the tubes. The tubes with the holes located furthest away from the main jet install in the rear carbs.








Set the float height by holding the carb on its side until the float just stops closing. Then measure the distance from the top of the float to the bowl surface. If you lay the carb down it will distort the reading. Adjust the height by bending the metal tab on the float. A dial or digital caliper back end works well for setting the height. If you get different readings on each side of the float, use an average of the two readings.
Install the float bowl with gasket and 4 screws tightly. Tighten the drain plug in the bowl.

Assemble the spring, washer and o-ring in that order on the slow speed needle. Screw in the needle assembly until it just bottoms out. Then open the number of full turns recommended.





Assemble the choke valves, lifter arm, spring, black sleeve, black nut and linkage plate. Don't break the plastic nut. Test by moving the choke lever (where the cable attached) and verifying that the valve opens about 3/8" and closes with a slight clearance between the head of the valve and the fork. You may need to wait to do this until all 4 valves are assembled. If they don't function correctly, adjust the linkage by bending.

Install all sync springs at this time. Remember there is a spring on the sync screw and a spring between the two tabs. Use those pictures you took for reference.













Bench check the sync of the carbs.
#1 carb is adjusted with the black idle knob. Place a 1/8 inch wide strip of printer paper between the throttle plate and bore on # 1 carb. Adjust the black idle knob until there is a slight drag on the paper.
Next, place a strip into #3 carb. Adjust the screw on the linkage for the same drag. There must be 2 springs on the adjuster for it to work properly. One on the screw, one in the linkage.
Verify that the linkage between the front and rear carbs is in place and that the bushing are tight.
Next, place a strip into #2 carb. Adjust the screw on the linkage for the same drag. There must be 2 springs on the adjuster for it to work properly. One on the screw, one in the linkage.
Next, place a strip into #4 carb. Adjust the screw on the linkage for the same drag. There must be 2 springs on the adjuster for it to work properly. One on the screw, one in the linkage.

An alternative method uses the small hole in the carb throat to set the plates. The plates should be set so that half the hole is visible. The hole is opposite the paper shown in carb #1.





Cycle the throttles to make sure the settings repeat.

With the carbs mounted to the plenum do the following before you put them on the engine
1. Do a bench sync and make sure all the little springs are in the throttle linkage. Make sure that the linkage bushings are not worn out, this can cause sync problems. All 4 throttle plates should move at the same time.
2. Move the choke lever and verify that all 4 choke valves are opening and closing fully. Adjust (bend) linkage to get them all working and have clearance at the valve to fork when closed.
3. Hook up a shop vacuum to the engine side of each carb. Open the throttle with the vacuum running. The slide should open, and close quickly when the throttle is closed.
4. Some people fill the carbs with fuel before installing to make sure there are no leaks.

Now is the best time to change the o-rings on the 2 coolant tubes in the V of the engine. It can be done with the carbs in, but not easily.
After reinstalling the carbs on the bike and before you hook up the fuel line, FLUSH the fuel lines to remove any debris. Or you may be doing this procedure again.

After reinstalling the carbs on the bike a sync of the carbs should be done using gages. This will compensate for the minor differences in flow to each cylinder. With a good bench sync, most people find that there will not be much change needed. Do this sync in the same 1,3,2,4 order.

The manuals describe an idle drop method to adjust the low speed needles. It is somewhat difficult to do and the results people have had are varied. Give it a try if you want, but most people get back to just about the recommended settings. I prefer to start with the recommended and then close each needle a quarter turn in. Ride the bike and verify that acceleration has not been affected. Try an additional quarter turn and verify acceleration. If performance falls off, go back one step. This leaning of the mixture procedure will improve your mileage and improve hot starting in high temperature conditions."

[Switchblade]

Boy i wish this site was available in 95 oh yeh and the intranet ...

[cruzinaz]

Boy i wish this site was available in 75 oh yeh and the intranet ...

Ya, no kidding! ...Oh and I had to change that timeline a touch

[Guest]

Interesting post.

Mr. Carr's kits are well thought out and inclusive, a real boon to the DIY'er. I don't know if he has a kit for VF500 carbs, which use different fuel joint orings than the others, but overall a good deal to which his ebay feedback attests.

However, there are a couple of minor details that I might add.

For one, most of the V4 carbs have different sized main jets for the front and rear, not just the positions of the aeration holes in the emulsion tubes on the 1-3 and 2-4 bodies.

Plus, many models use different slide needles as well--the forward pair of carbs being set up to run more lean than the rear.

If these components get mixed up during assembly you can have all manner of quirky and nearly impossible to pinpoint behaviors. This underscores the need to carefully compartmentalize the bits.

Too often, guys get ahead of themselves and put parts into a common container, which is fine if you know where everything goes but it can bite you on the rear.

And last, it's not uncommon for the choke linkage rods to become bent, either by a PO or well-intentioned home mechanic. A kink in a fixed-length rod shortens it, and thus you can have a situation where one or more of the chokes don't close all the way even though you get proper feedback from them. Unless you know precisely what to look for this too can be the source of much aggravation, which (like mixed up jets and needles) you won't know until you're on the road.

V4 carbs aren't that difficult for a home mechanic to service despite looking like a rube goldberg contraption at first glance. You just need to be aware of the pitfalls.

OSC

http://www.oldschoolcarbs.com

[MaxSwell]

When using a philips-head screwdriver on Japanese bikes, they use a different shaped screw head then SAE philips-head screws. I cannot locate it now but Motorcycle Consumer News did an article on this problem. I've bought a set of these Japanese spec screwdrivers and it makes a huge difference in the removal of philips-head screws. No more butchering the head when torque is applied. Highly recommended for DIY Japanese bike owners.

[Guest]

When using a philips-head screwdriver on Japanese bikes, they use a different shaped screw head then SAE philips-head screws. I cannot locate it now but Motorcycle Consumer News did an article on this problem. I've bought a set of these Japanese spec screwdrivers and it makes a huge difference in the removal of philips-head screws. No more butchering the head when torque is applied. Highly recommended for DIY Japanese bike owners.

You mean like these? http://www.oldschoolcarbs.com/vessel-jis-driver-set/

[MaxSwell]

When using a philips-head screwdriver on Japanese bikes, they use a different shaped screw head then SAE philips-head screws. I cannot locate it now but Motorcycle Consumer News did an article on this problem. I've bought a set of these Japanese spec screwdrivers and it makes a huge difference in the removal of philips-head screws. No more butchering the head when torque is applied. Highly recommended for DIY Japanese bike owners.

You mean like these? http://www.oldschoolcarbs.com/vessel-jis-driver-set/

Yup. JIS. I got three cross head sizes. The middle-sized P.2 x 108 is the most useful. The large-sized P. x 150 is too big for anything I've come across on the '01.

[zoomzoom]

Carbs are not difficult at all, just be organized. To do a good carb clean. Have him read this...really should be a sticky in here.

***DO NOT remove the aluminum plate that holds the 4 carbs together. You can do a pretty good job of cleaning without separating the carbs. The guide shows them completely apart but you don't have to get that crazy. When Billy does them, everything does get broken down.***

From V4BBS, for quick reference...

"The V4 engines use 4 constant velocity (variable venturi) carburetors to supply fuel to the engine. The constant velocity refers to the air speed through the throat of the carb. The velocity is controlled by a slide mounted to a diaphram. The diaphram is sensitive to vacuum created by the flow of air across a hole(s) in the needle end of the slide. As the engine speed increases, the vacuum above the diaphram increases due to venturi action and the slide is raised.

There are three circuits (paths) in the carb.

The starting circuit (choke) provides extra fuel when the choke is open. It uses a fixed jet and a choke plunger to control the flow of fuel to the port in the carb throat. The restriction is the fixed jet at about 0.021 inches. The choke plunger also provides an air bypass around the throttle plate to increase the engine speed during warm up.

The low speed circuit provides the primary fuel for operation below 4000 to 5000 rpm. When the engine is pulling vacuum the fuel is drawn through a passage to the low speed needle valve, and then to a large hole on the bowl side of the throat on the engine side of the throttle plate. The needle valve controls flow to the large hole. This path also feeds the 4 tiny holes on the float side of the throat and under the throttle plate. Both paths continue to function at all engine speeds. The restriction is the low speed needle or the low speed jet.

The high speed circuit provides fuel above 4000 rpm. It uses a fixed orifice and a needle connected to the slide to control the flow of fuel to the needle valve opening in the carb throat. As engine speed increases the slide raises the needle and allows additional fuel to flow. The restriction is the needle valve on the slide. Since the needle valve never completely closes, the circuit provides fuel at all engine speeds.

It should be verified that fuel is getting to the carbs. Verify you are getting a flow of fuel at the inlet hose to the carbs. No flow can be caused by delivery problems due to tank venting, plugged screen in the tank, pinched hoses, fuel pump problems or fuel filter plugged. Or you could be out of gas.

The main symptoms of carb trouble are.

1. Hard cold starting that is caused by restricted choke circuit, low speed circuit or improper fuel level in the float bowl. Failure modes that cause this are.

a. Plugged low speed jet. The jet must be removed and cleaned.

b. Plugged choke jet. The jet cannot be removed, it must be cleaned in place.

c. Plugged low speed circuit and choke circuit passages from the jet to the carb throat. The carburetor must be removed and the passages cleaned.

d. Improper fuel level in the float bowl. The float valve and screen must be removed and cleaned. The float must then be set to the correct level.

e. Improper setting of the low speed needle valves. In most cases resetting them to the factory recommendation will be satisfactory.

2. Poor idling and hesitation when accelerating up to 4000 rpm caused by restricted low speed circuits or improper fuel level in the float bowl. . Failure modes that cause this are.

a. Plugged low speed jet. The jet must be removed and cleaned.

b. Plugged low speed circuit passages from the jet to the carb throat. The carburetor must be removed and the passages cleaned.

c. Improper fuel level in the float bowl. The float valve and screen must be removed and cleaned. The float must then be set to the correct level.

d. Improper synchronization of the 4 carburetors. They may synced while on the engine using vacuum gages or mercury sticks.

f. Improper setting of the low speed needle valves. In most cases resetting them to the factory recommendation will be satisfactory.

3. Poor operation above 4000 rpm caused by improper slide operation or improper fuel level in the float bowl. Failure modes that cause this are.

a. Ripped diaphram. Ripped diaphrams must be replaced, usually with the carbs off the bike.

b. Leaking diaphram. If the diaphram is not seated correctly in the cover it will leak air and defeat the vacuum action.

c. Sticking slide. The slide must be removed and any contamination removed.

d. Choke valve not closing completely.

e. Incorrect high speed jet or emulsion tube installed. Verify correct parts.

f. Incorrect spring installed over the slide. Verify correct springs.

g. Incorrect high speed needle installed. Verify correct needle.

Carburetor Cleaning and Rebuild

There are 3 approaches to cleaning the carbs.

Use an additive in the gas tank such as Techtron or Sea Foam.

Do the disassembly and cleaning yourself.

Send them to a professional for a super cleaning.

The additive route sometimes works if the plugging of circuits is not too bad.

The do it yourself method will achieve well functioning carburetors that looks like they did when you took it off.

The professional cleaning by Billy Carr will make them shine and function like new with the added advantage that he has any needed replacement parts. BBS friendly carb cleaning service

To quote Billy, "being the local carb guy means I get mine either way. I rebuild them... I get paid. You do them yourself with my cheap carb kit ... I get paid. Buy the carb kit and in a few hours and you can have a resealed long lasting set of carbs. Never be afraid to delve in to a set of carbs unless you do not possess the simple ability to tell which end of a combination wrench is which. Worst case scenario is you mail me a bucket full of parts when you realize you got in over your head. Saves me teardown time."

Sample of his work.

Helpful hints if you do them yourself.

Take photos of the carbs installed, cable routing, removed still on the plenum from all angles. You will treasure them when you put things back together.

Remove all 4 carburetors and the plenum (air box) as an assembly.

Drain the fuel from each carb through the drain nipple by opening the needle screw in the bottom of the float bowl.

If the carb rack (all 4 carbs bolted to the plenum) is dirty clean it with a degreaser before you start to take things apart.

When you disassemble your carbs keep the parts separated by individual carb as they are different from front to rear in many cases (baby food jars are great). Note, after 30 years and many owners the parts may not actually be in the correct location. Always refer to manual for the correct placement and part. The model number will be stamped on the flange above the float bowl.

Do not be afraid to use a permanent marker in an out of the way spot to keep the carbs straight (number the baby food jars too). They are numbered #1- #4 left to right as you sit on the bike.

If you do not split the rack you will not have to hassle with the linkages and the throttle plate synch will be much easier. You will not be able to change the fuel and air tube o-rings however, your call.

Use a good #3 Philips tip screw driver bit or impact bit to loosen all screws. Tap each one a couple of times with a hammer and bit before you try to loosen them

Your work area should someplace where you can track down parts that may escape you.

Do It Yourself Rebuild

Buy a carb rebuild kit from Billy C at BBS friendly carb cleaning service

It has everything you need plus a DVD filled with information.

One carb at a time, remove the 4 screws that hold the float bowl on. Check condition of the o-ring seal. If hardened, get new ones. If they have never been replaced they will be hard and flat.

Remove and clean the drain plug and clean the drain nipple if plugged.

Remove the pin holding the float in place, remove the float and needle.

Remove and check the condition of the needle seat and screen.

Remove the high speed jet and holder (emulsion tube). Make sure all holes are clean.

Remove the low speed jet. Make sure all holes are clean especially the one through the center, clean with a 0.015 inch wire or #79 pin drill for 38 size jets. The size of the jet is stamped on it. 38 stands for 0.38 mm or about 0.15 inches.

The choke jet cannot be removed, pressed in. Clean the hole through the center of it, clean with an 0.021 inch wire or a #75 pin drill.

Inspect all passages and blow air or a solvent through them. Look into each hole with a good light and a magnifying glass.

Login 20pc Drill Bits #61-80 and Pin Vise

Remove the low speed needle from the side of the carb just above the float joint. It may be covered with an aluminum cap to prevent tampering. If it is, drill a 1/8 inch hole in the cap, drive in a sheet metal screw a couple of threads and pull the cap out. Before unscrewing the needle, turn it in counting the number of rotations until it seats lightly. The needle will have a spring, flat washer and o-ring behind it, remove them.

Inspect all passages with a good light and a magnifying glass and blow air or a solvent through them.

Remove the choke valve by removing the black plastic nut, the linkage plate, the black linkage sleeve and spring. Work it out as an assembly. Be careful, the black nut is fragile.

Take some more pictures of where all the linkage goes.

Blow air through all the passages to clean, including the choke jet.

On the other side of the carb, remove 4 screws holding on the chrome cover. Be alert, it is spring loaded.

Remove the diaphram cover and spring.

Remove the diaphram slide assembly. Carefully inspect the diaphram for any tears or cracks. If any found, big and expensive problem to replace. Clean the slide and its bore of any residue. Don't use carb cleaner on the diaphrams, it will damage them. Use a 0.018 inch wire or pin drill #77 to clean the brass orifice located under the diaphram cover. This orifice appears to be a drain for any fuel accumulated in the top of the diaphram.

With all the jets, needles, slides and chokes removed, blow air through all the passages including the choke jet. Blow air through the small ports in the carb throat to verify that they are clear. Soaking in a cleaner may now be done safely.

***THIS IS NOT MANDATORY, I WOULD SKIP THIS UNLESS YOU HAVE FUEL LEAKAGE FROM THE TUBES***

Now is the time to replace the o rings on the fuel rail if you plan on doing it. Be very careful with the tubes as they can be broken with sideways pressure. The o rings are included in the Billy C kit.

Use a quality #3 Philips head screw driver to loosen the 8 screws holding the carbs to the plenum. Tap them with a bit and hammer to break them loose. Leave all screws in place until they all have been broken loose.

Take pictures of all the springs on the throttle linkage.

Remove the 8 screws and remove the plenum. There are locator dowels on each carb that may require prying out for separation. BE CAREFUL the sync and shaft springs will fall out when you separate the carbs. You did take those pictures right? The tubes are unique so keep track of what goes where.

Remove the o rings from the tubes and replace with the new ones.

Clean the holes that the tubes insert into. Did you notice that the fuel path runs straight through the bottom of all 4 carbs?

Carefully insert the fuel tubes back into the carb bodies along with the vent tubes if your model has them. Do not let the o ring roll out of the groove. The throttle adjuster plates and shaft springs must also be lined up for each carb. Do not worry about the sync springs at this point.

Replace the plenum with new socket head cap screws M6-1.00 x 20. You do not want to mess with the Philips the next time. They are available at most hardware stores for about $.50 each. Evenly tighten the screws making sure that the tubes and shafts are not binding. Boiling the air funnels makes them easier to install. Old ones shrink and are a pain in the ass to get in place. Make sure the line on the funnel is between the two index lines on the airbox.

When you are satisfied that everything is clean, begin reassembly.

Assemble the diaphram slide assembly into the carb, make sure the hole(s) in the diaphram align with the holes in the carb.

Assemble the spring and cover. Short vacuum piston springs install in the rear carbs, long springs install in the front carbs. Make sure the diaphram seats into the groove. Tighten 4 screws. To test seating, hook a shop vac up to the engine side of the carb and open the throttle plate. The slide should rise, then fall when the throttle is closed. If it doesn't the diaphram is not seated.

Gently flex the floats to check for cracks. They like to crack where the lattice meets the float---and then they fill up with gas. You'll notice the float full of fuel if you tear down quick after carb removal. Otherwise you won't know without careful inspection.

Inspect your float needles. The rubber tip on can pull out of the metal needle and bind up the valve.

Carefully clean the choke plungers. It makes them operate smoother and prevents them from hanging up. Some fine emery paper works well for this. Inspect the end of the choke valve for the condition of the rubber insert. If it is badly worn in may be removed and flipped over. Replacements are not available.

Assemble the high and low speed jets in the carb tightly. Verify the correct size is used in the correct location. The fuel emulsion tubes that the main jets thread into are different between front and rear carbs. There are low drilled holes and high drilled holes in the tubes. The tubes with the holes located furthest away from the main jet install in the rear carbs.

Set the float height by holding the carb on its side until the float just stops closing. Then measure the distance from the top of the float to the bowl surface. If you lay the carb down it will distort the reading. Adjust the height by bending the metal tab on the float. A dial or digital caliper back end works well for setting the height. If you get different readings on each side of the float, use an average of the two readings.

Install the float bowl with gasket and 4 screws tightly. Tighten the drain plug in the bowl.

Assemble the spring, washer and o-ring in that order on the slow speed needle. Screw in the needle assembly until it just bottoms out. Then open the number of full turns recommended.

Assemble the choke valves, lifter arm, spring, black sleeve, black nut and linkage plate. Don't break the plastic nut. Test by moving the choke lever (where the cable attached) and verifying that the valve opens about 3/8" and closes with a slight clearance between the head of the valve and the fork. You may need to wait to do this until all 4 valves are assembled. If they don't function correctly, adjust the linkage by bending.

Install all sync springs at this time. Remember there is a spring on the sync screw and a spring between the two tabs. Use those pictures you took for reference.

Bench check the sync of the carbs.

#1 carb is adjusted with the black idle knob. Place a 1/8 inch wide strip of printer paper between the throttle plate and bore on # 1 carb. Adjust the black idle knob until there is a slight drag on the paper.

Next, place a strip into #3 carb. Adjust the screw on the linkage for the same drag. There must be 2 springs on the adjuster for it to work properly. One on the screw, one in the linkage.

Verify that the linkage between the front and rear carbs is in place and that the bushing are tight.

Next, place a strip into #2 carb. Adjust the screw on the linkage for the same drag. There must be 2 springs on the adjuster for it to work properly. One on the screw, one in the linkage.

Next, place a strip into #4 carb. Adjust the screw on the linkage for the same drag. There must be 2 springs on the adjuster for it to work properly. One on the screw, one in the linkage.

An alternative method uses the small hole in the carb throat to set the plates. The plates should be set so that half the hole is visible. The hole is opposite the paper shown in carb #1.

Cycle the throttles to make sure the settings repeat.

With the carbs mounted to the plenum do the following before you put them on the engine

1. Do a bench sync and make sure all the little springs are in the throttle linkage. Make sure that the linkage bushings are not worn out, this can cause sync problems. All 4 throttle plates should move at the same time.

2. Move the choke lever and verify that all 4 choke valves are opening and closing fully. Adjust (bend) linkage to get them all working and have clearance at the valve to fork when closed.

3. Hook up a shop vacuum to the engine side of each carb. Open the throttle with the vacuum running. The slide should open, and close quickly when the throttle is closed.

4. Some people fill the carbs with fuel before installing to make sure there are no leaks.

Now is the best time to change the o-rings on the 2 coolant tubes in the V of the engine. It can be done with the carbs in, but not easily.

After reinstalling the carbs on the bike and before you hook up the fuel line, FLUSH the fuel lines to remove any debris. Or you may be doing this procedure again.

After reinstalling the carbs on the bike a sync of the carbs should be done using gages. This will compensate for the minor differences in flow to each cylinder. With a good bench sync, most people find that there will not be much change needed. Do this sync in the same 1,3,2,4 order.

The manuals describe an idle drop method to adjust the low speed needles. It is somewhat difficult to do and the results people have had are varied. Give it a try if you want, but most people get back to just about the recommended settings. I prefer to start with the recommended and then close each needle a quarter turn in. Ride the bike and verify that acceleration has not been affected. Try an additional quarter turn and verify acceleration. If performance falls off, go back one step. This leaning of the mixture procedure will improve your mileage and improve hot starting in high temperature conditions."

Hey Kel

Thank you very much for one of the most informative posts I think I have ever seen. I have emailed a link to this post to my buddy Doug in Calgary. Hopefully the information contained within your post will give him the confidence to try the carbs himself. After reading your post, I think I might even be able to muddle my way through it without much trouble as the post is extremely informative.

And thanks to all the members who posted up offers and solutions. I must admit to not keeping track of this particular thread as the bike belongs to my buddy Doug and I suggested that he check it from time to time. As yet, he has not done anything as he has been crazy busy with work.

[Guest]

The manuals describe an idle drop method to adjust the low speed needles. It is somewhat difficult to do and the results people have had are varied. Give it a try if you want, but most people get back to just about the recommended settings. I prefer to start with the recommended and then close each needle a quarter turn in. Ride the bike and verify that acceleration has not been affected. Try an additional quarter turn and verify acceleration. If performance falls off, go back one step. This leaning of the mixture procedure will improve your mileage and improve hot starting in high temperature conditions.

I must resepectfully disagree with you. I'm curious to know if Mr. Carr agrees. Hello? LOL.

Lean running contributes to premature engine wear/failure and is correctly described as the bane of normally aspirated engines. I whinge about this to everyone, and the need to check compression values (and for the V4's, cams), as a strict precondition to diving in to the carbs.

Hard-starting when hot is generally the result of poor compression, mis-adjusted valves, and clogged slow circuits. Poor compression (like a clogged air cleaner) mimics rich, but only superficially. And if it's due to too-close valves or chewed up cams you've got a bucket full of problems that carb adjustment won't even begin to mitigate.

Yes, overly rich conditions do exist in bikes that haven't been serviced for many years but it's so rare that it scarcely deserves mention. As a general rule of thumb, age and wear cause bikes to go lean, not rich.

I've got countless v4 carbs out there over the years. My own VF1000r, acquired with 30K on it, had 95K miles when the odometer made a horrible noise and quit about five years ago. I don't know that I've seen a V4 with more miles on it, except for my old V65 magna that died at 115K. Just sayin'.

Our standard "fix" is to seek that sweet spot where we're just this side of being too rich that we lose power under WOT. We go up a size on the mains and set the pilot needles 3 turns out as a starting point.

We find cooler running temps under hard riding, great fuel economy (which is the counter-intuitive part) , and most of all longevity. We here in the SF bay area have a lovely mountain road that goes from sea level to 2200'. A restart at the summit after an 8000 rpm run up the steepest parts will tell you how you're doing insofar as valves, carbs, etc.

The rules are different for racing, but those guys have their engines down every year so they get a pass on squeezing out every bit of energy per unit volume of fuel.

Let your pal know that I've got a set of VF1000 carbs just sitting here. Probably too late for this season but it's there for a quick swap if he's interested.

OSC

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Hey OSC

Are the carbs off a 1985 VF1000 "F" or a 1000 "R". Not sure if that makes a difference or if the US models differ much from the Canadian models. I will mention to my buddy Doug that you have a set. Alas, the "S" word has already reared it's ugly head around the Calgary,AB area here in Canada and the fluffy white stuff will likely end what is left of riding season. Not that he had much of a riding season this year. Poor guy was off work for about 3 months after a MVA while on his way home from Edmonton. Thankfully he was not badly injured but he tore some muscles in his shoulder and it took a long time before the companies doctor took him off light duty roster. This left him doing all kinds of driving (he works in the oil patch) and he was basically a highly paid taxi driver and courier until they got him back on regular duty. It wasn't until his accident that he tried starting the bike this spring that he realized he had forgotten to add fuel stabilizer to the tank after he ran the bike last (about 16 to 18 months or more as I recall him mentioning) and he removed the float bowl on one of the carbs and there was definitely a thick molasses style substance in there. The cams and everything else on the bike were in fantastic condition as I had the valves adjusted and the timing chain and chain tensioners replaced before I gave him the bike and the mechanic at the Honda dealer said that the cams were in next to new condition,and the motor was one of the best running VF1000F's he had the pleasure of working on in his 30 year career. Doug has not put a huge number of miles on the bike since I gave it to him and said it was running great prior to storing it.

I will let him know about your offer and I'll have him let me know if he wants to take you up on the offer. Are you interested in just swapping carb assemblies as a whole and him paying the shipping costs or would you like a little cash as well?? PM me if you like and let me know.

Thanks again

Bill

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Direct him to my website and perhaps bookmark it, so that when such time arises that he wants to make the connection it won't depend on me only periodically browsing the forums.

http://www.oldschoolcarbs.com

Canadian models are jetted slightly more rich than US 49-state, and still more so than the California-approved models. The ones I have are from an '84, but they're fully compatible across the make. They might even be canadian, which shipped with user-accessible air/fuel mixture (pilot) needles. I'll have to look---I took them in trade with another Canadian chap. I don't hold it against him that he's a Canucks fan. Go SHARKS! LOL.

Jack

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Actually he's a Flames fan, since he lives in Calgary, AB. I keep telling him the Canucks are the better team, but he always disagrees. LOL

I have sent him a link to your website, OSC. I also emailed him a copy of the form you need him to send with the carbs so that he doesn't have to try doing that himself (don't ask and Doug won't feel bad)