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My 89 vfr won't pass 3000rpm


89vfrrc24

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21 hours ago, DannoXYZ said:

Irrelevant test because you're sending power to starter and it spins. Diode provides ground-leg to starter-solenoid.

 

Test and verify entire starter-circuit by measuring for +12v on starter-terminal when you push START-button.

IF you have power at starter, then EVERYTHING in chain from battery to power-cable to ignition-switch to kill-switch to start-button to starter-relay to starer-solenoid to power-cable to starter is working properly and don't waste any more time on any of that. Problem lives elsewhere. But you already knew that because starter spins when you push start-button.

 

 

You caused some damage here. Did you find it and fix problem?

Today i will test a new CDI.

 

I'm betting everything on it!!!!

 

the symptoms are precisely all those that a bad cdi causes.

image.thumb.png.49f043b86e0b52c29d52f22e61b1c5c5.png

 

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Sure, very well could've zapped your ignition-box with whatever short you had when pushing start-button.

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I have 3 VFR's and not one of them ever had a CDI problem.  One even has a HRC cdi which still works. After rebuilding my carbs last summer with a rebuilt kit from AliExpress I only replaced the float needle and bowl gasket and polished up the needle because I left gas in the bowls.  Keep in mind this bike has not started since 2006 btw the carbs were all gummed up and walla it started right up and revved up.  If you do not see the slides going up and down when revving the engine make sure to remove the complete airbox and push up on all the slides to see if they are moving. The needle from the slide directly affects how much gas is being let in.  From your last picture it clearly shows these carbs were not rebuilt correctly. Did you remove the float needle to see if it is gummed up? Behind it is a screen that need to be cleaned out.  No gas coming in means no gas going out into the motor.  When I rebuild carbs I let them sit in pine-sol for a day  I remove only the float needle and main jet and pilot jet must count turns and do not loose al those little o rings and spacers and blast them with a hose and compressed air then I clean them out with carb cleaner and small brushes to clean everything orifice.  By missing on component  just a little bit and the bike will not run correctly.  

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Also only use OEM components for carb rebuilds. Aftermarket kits are notorious for not having compatible pieces. Jets that are all wrong sized, not even matching within same kit. Seals that don't fit and leaks, etc. Really need ultrasonic soak and micro soda-blasting as part of carb restoration job.

 

Send your carbs to squirrelman on this board. He's got more experience with restoring these carbs than anyone. They'll come back factory-fresh OEM clean and bike will run like brand-new off showroom floor!

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Does the bike run pretty good with the choke on and then once the choke is off it doesn't rev up? If so then there is something most likely wrong with the carbs. Your initial post says when it warms up it won't rev.

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2 hours ago, VFR750F3 said:

I have 3 VFR's and not one of them ever had a CDI problem.  One even has a HRC cdi which still works. After rebuilding my carbs last summer with a rebuilt kit from AliExpress I only replaced the float needle and bowl gasket and polished up the needle because I left gas in the bowls.  Keep in mind this bike has not started since 2006 btw the carbs were all gummed up and walla it started right up and revved up.  If you do not see the slides going up and down when revving the engine make sure to remove the complete airbox and push up on all the slides to see if they are moving. The needle from the slide directly affects how much gas is being let in.  From your last picture it clearly shows these carbs were not rebuilt correctly. Did you remove the float needle to see if it is gummed up? Behind it is a screen that need to be cleaned out.  No gas coming in means no gas going out into the motor.  When I rebuild carbs I let them sit in pine-sol for a day  I remove only the float needle and main jet and pilot jet must count turns and do not loose al those little o rings and spacers and blast them with a hose and compressed air then I clean them out with carb cleaner and small brushes to clean everything orifice.  By missing on component  just a little bit and the bike will not run correctly.  

Thank you so much for your explanation.

Like @jeffersonsaid, i will make a video with the choke on  , and make a cold start. 

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Your Ignition Module or Spark Unit is not a CDI type! More likely its a Digitally Controlled Transistorised Ignition Unit.

The coil primary windings are provided with constant 12v then the Spark Unit provides high speed switching to Ground to pulse the primary winding of the Ignition coils.

 

Perhaps a good check of the two Pulse Generator pickup coils ( for cylinders 1-3 and 2-4) should be done!

From the information I've found for a 1987 - 1989 RC24 the resistance of these two coils should be between 200 to 400 ohms each. Check these both hot and cold. One of these coils breaking down or having faulty wiring or connections would create the symptoms typical of the video you posted.

Also perform a continuity check of the Pulse Gen wiring back to the Spark Unit - make sure you have good continuity for each wire, source to destination.

 

Make absolutley sure that the Green Ground wire of the Ignition Module is very properly bonded to Ground ie. Zero Ohms resistance back to the Battery Negative Terminal, make sure that with Ignition to On you have a solid 12v supply to the Ignition Module on the Black/White wire. NOTE this voltage is fed from your Kill Switch, so make sure there's nothing flakey with the Kill Switch!

 

I've also confirmed that for a 1989 model the Starter Clutch outer should have 11 Pulse Trigger Bumps. This matches up with your Clutch Outer photos, appears you do have the correct clutch outer.

 

If you have it? Refer to the circuit diagram and/or service manual for your model regards where to easily measure the P/G pickup coils.

Good Luck.

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7 hours ago, Grum said:

Your Ignition Module or Spark Unit is not a CDI type! More likely its a Digitally Controlled Transistorised Ignition Unit.

The coil primary windings are provided with constant 12v then the Spark Unit provides high speed switching to Ground to pulse the primary winding of the Ignition coils.

 

Perhaps a good check of the two Pulse Generator pickup coils ( for cylinders 1-3 and 2-4) should be done!

From the information I've found for a 1987 - 1989 RC24 the resistance of these two coils should be between 200 to 400 ohms each. Check these both hot and cold. One of these coils breaking down or having faulty wiring or connections would create the symptoms typical of the video you posted.

Also perform a continuity check of the Pulse Gen wiring back to the Spark Unit - make sure you have good continuity for each wire, source to destination.

 

Make absolutley sure that the Green Ground wire of the Ignition Module is very properly bonded to Ground ie. Zero Ohms resistance back to the Battery Negative Terminal, make sure that with Ignition to On you have a solid 12v supply to the Ignition Module on the Black/White wire. NOTE this voltage is fed from your Kill Switch, so make sure there's nothing flakey with the Kill Switch!

 

I've also confirmed that for a 1989 model the Starter Clutch outer should have 11 Pulse Trigger Bumps. This matches up with your Clutch Outer photos, appears you do have the correct clutch outer.

 

If you have it? Refer to the circuit diagram and/or service manual for your model regards where to easily measure the P/G pickup coils.

Good Luck.

Hi @Grum, thank you for your explination.

 

I already have measure the pulse generators and even order a NOS ones from germany, because of slight difference. One was at 292 and other one 304 (photos). things i didn't do:

 

- check the continuity between the Pulse and  Spark unit;

- check the ground on ingnition module;

 

Alreaday check the kill switch and the tachometer... everything is ok.

 

 

328501545_459205812957974_8093936281043115556_n.thumb.jpg.f96702117dc763fb6924f3be85ffdd72.jpg328477857_1419825098833101_3585386550821454494_n.thumb.jpg.e1f86273f31c8a7737571ea0dcef49b7.jpg

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16 hours ago, VFR750F3 said:

I have 3 VFR's and not one of them ever had a CDI problem.  One even has a HRC cdi which still works. After rebuilding my carbs last summer with a rebuilt kit from AliExpress I only replaced the float needle and bowl gasket and polished up the needle because I left gas in the bowls.  Keep in mind this bike has not started since 2006 btw the carbs were all gummed up and walla it started right up and revved up.  If you do not see the slides going up and down when revving the engine make sure to remove the complete airbox and push up on all the slides to see if they are moving. The needle from the slide directly affects how much gas is being let in.  From your last picture it clearly shows these carbs were not rebuilt correctly. Did you remove the float needle to see if it is gummed up? Behind it is a screen that need to be cleaned out.  No gas coming in means no gas going out into the motor.  When I rebuild carbs I let them sit in pine-sol for a day  I remove only the float needle and main jet and pilot jet must count turns and do not loose al those little o rings and spacers and blast them with a hose and compressed air then I clean them out with carb cleaner and small brushes to clean everything orifice.  By missing on component  just a little bit and the bike will not run correctly.  

Thank you for the explination  @VFR750F3. I never had remove this carbs. I removed them,  and had troubles unscrewing the float bowls because of the angle of the screws. The only thing I did was clean all the jets with the air compressor. When I put the 332107274_1814625605584217_1164182999894893712_n.thumb.jpg.6381912eab3b71ff4cd59a1b66f31af8.jpg

 

 

compressor directly on a tube, all the floats went up. I assumed it was all good.

 

I think the slides are all moving now. (see the vídeo please)

 

 

 

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This is the float needle you need to remove and check the screen and float needle.  They must be clean and or replaced it this is very important.  Do not bend the tab on the float this will mess everything up.  Like I said before.  Did you take the carbs off the bike?  You cannot rebuild gummed up carbs without taking them off.  Trust me I have tried and failed.  Everything must be spotless in the there.  

float.jpg

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I just had a though lol.  Will others chime in.  If you spray carb cleaner into the carbs while the engine is running and rev the engine before you choke it with carb cleaner.   Will this particular engine rev higher than 3000 rpms proving it is a fuel problem instead of a ignition problem?  A episode for MYTHBUSTERS.

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Sure, try squirt bottle with actual petrol. Lots of modern carb-cleaners aren't as combustible.

 

uc?export=download&id=1FLmcUVQLstVGh6HnC

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On 2/25/2023 at 1:58 PM, VFR750F3 said:

I have 3 VFR's and not one of them ever had a CDI problem.  One even has a HRC cdi which still works. After rebuilding my carbs last summer with a rebuilt kit from AliExpress

 i had a problem with the box on my '86 where it quit firing just one cylinder.  bad box for sure.

 

you're taking too many chances by using cheap crap alierxpress chinese junk in your carbs.

 

we still want to see your sparkp;lugs........

 

this is the best way to be sure idle jets are fully open, compressed air won't do it:

 

post-3647-0-85981000-1347898810.jpg.16f3ebc5cb2650ba3b01a67c8e0f6869.jpg

 

 

 

 

gallery_3647_3505_386750.jpg.2297523b09532bb33ee2a2d05b09a84c.jpg

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You have got some of the best engine wizards in the county trying to help you solve your problem.

I know this is a very long shot and may have been mentioned already but what is the condition of your carb intake rubbers?

I have a 1990 and it was doing some very strange things after I had the carbs rebuilt, in the end I found one of the intake rubbers

( which looked great ), was hard and dried out I could rotate it on the engine, I figure it was sucking air at start up and a hell of a lot more when she was warm, The Capt. pointed out that the factory bands has torque limiting spacers on the screws and when the intake rubbers dried out and shrunk you are not able to get the intake rubbers tight enough

Good Luck

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By the looks of your float screens these carbs were not rebuilt or cleaned correctly. Did you replace fuel filter?  Is there rust in the gas tank?  Did the bike ever run correctly and when? You showed no picture of your float needle.  You must clean all varnish and blow out everything.  Make sure you use a flashlight to make sure all those little holes in the main jet are clear and blow those out also.  Every year my snowblower main jet clogs because I get lazy and leave fuel in it.  All those tiny little holes are very important and if they get clogged.  As I said before do not forget the slide jet needle venturi etc. Pilot jets are they clean.  You need to download the repair manual and learn about this.

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7 hours ago, VFR750F3 said:

By the looks of your float screens these carbs were not rebuilt or cleaned correctly. Did you replace fuel filter?  Is there rust in the gas tank?  Did the bike ever run correctly and when? You showed no picture of your float needle.  You must clean all varnish and blow out everything.  Make sure you use a flashlight to make sure all those little holes in the main jet are clear and blow those out also.  Every year my snowblower main jet clogs because I get lazy and leave fuel in it.  All those tiny little holes are very important and if they get clogged.  As I said before do not forget the slide jet needle venturi etc. Pilot jets are they clean.  You need to download the repair manual and learn about this.

@VFR750F3the fuel filter was clogged. The bike didn't run, because no gas was coming to the carburetores. Bought a new one and replaced the old one. I don't know what impact it had on the carbs... thats why i am cleaning or trying...first time i do this...

 

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That #2 plug looks alot better than those others. The others look really rich, but then running so badly could have caused that. Question then would be why #2 looks good.

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From looking at those strainers, carbs need serious work. Could be float valves not sealing well (except for #2) and letting float levels get too high causing excessive richness. Final test of float levels:

 

uc?export=download&id=1nW7XGpG_cBw5fGfH9

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The needle is the idle screw adjuster so you should remove them and ensure that the airway is clear on each carb

 

The float’s seem to be sticking, clean up and polish the spindles 

 

Correct float height is 9mm for an FK

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