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Looking to put together a group buy for replacement 4th gen carb vacuum pistons. These are the rubber diaphragm that moves the needle up and down. You cannot buy OEM replacements, and I'm not sure if you ever really could. If you have a torn diaphragm, or yours are just old and dry from being 20+ years old, this is for you. I met with Paul from JBM industries. Paul manufactures OEM replacement parts for many carbureted bikes, including isolator boots. Mike Norman used them on his NC35, and if they are good enough for him, they must be pretty good. He is confident in being able to make replacements. Because these diaphragms are only applicable for the 4th gen VFR, he would need a full order to cover his costs to make the initial batch. If you know other bikes that use these same diaphragms, let me know. http://jbmindustries.com/ Only the rubber diaphragm will be provided. Read through JBM's page on replacement instructions, but these will involve clipping the plastic ring off and gluing the new rubber on. He will mold in extra thickness to have the rubber replace the ring, as he has done with over parts. If you are not confident on replacing them yourself, we can work on having someone replace them for you. I will be providing a sacrificial set of parts for him to do his prototyping on if we make the orders. For Paul to go through with this, he needs a commitment of 30 sets at $80 per set of 4. This does not include shipping. He normally handles production of new molds and products at the beginning of winter, but will confirm if we get sufficient orders. Sign up, ask around, lets see if we can make this happen. I'm starting off with 3. Order list: (8/1/2018) 1. YoshiHNS 2. YoshiHNS 3. YoshiHNS 4. COS_VFR 5. SamW 6. Marsman99 7. scottbott 8. burnes45 9. LauraM 10. rangemaster 11. magpie114 12. Smack 13. Smack 14.vfrgo 15. vfrg0 16-26. Billy C 27. COS_VFR 28. kevinmacdonald 29. 30. @kgsmotorcycles @Dutchy @mcrwt644

Hi, I'm in a pickle. I've bought a bike and rebuilt the carbs along with some other things. I've never even heard it run and I'm soooooo close to trying to crank it over (tuned it by hand and it moves smoothly). Read the full story here. I haven't had any replies about my recent issue so I thought I'd post it in this forum...I've got some pretty itchy feet to try and turn her over on my day off today. I just need to figure out how to get the fuel feed hose to attach to the carbs. It's so simple but as you can see from my picture I'm either missing some sort of adaptor/bridging piece (? 16199-MAL-505 TUBE ?) OR the previous owner has managed to lodge a piece of plastic connector into the feed hose. I would really appreciate a guiding voice here. I'm thinking of pulling the plastic part sitting in the hose out and just connecting it to the t-joint. It seems it would make sense but I'm far from a mechanic! BJ

Ok guys so I've been busy dialing in the viffer. I got it dyno'd when I first got the bike and was running a bit rich, but the power curve was good and it ran great. I fixed the busted main header on cylinder 3, put on a non restrictive mid pipe, plugged the air box mod hole, put in a Piper cross air filter. Hoping I'd lean out a bit. I dyno'd it the other day and I'm even a bit richer that before. Dyno tech informed me that having better airflow could help make a richer environment for I'm pulling more volume and air which pulls more fuel as well. Which means I have carb work in my future. He said start by going down 5 on the main jets. I understand what that entails; so what size are the factory jets? Also I don't know if there was prior carb work done, if they aren't factory jets how would I tell the size of them so I could go down from it. I'm newer to carb work but I've been researching how they work and to better understand what I'll be doing. Just unsure of the specs for them. Any info helps and is much appreciated! Bottom chart if the first run on the dyno, top chart is the run I did Saturday. Also they changed the software and there's a 5% accuracy difference in number. So no I haven't lost power, I just have to lean her out a little to better my numbers.

I finally got the carbs removed! Thanks to all who offered tips. I didn't have to resort to my BFH. Since the tank was very rusty (now clean thanks to cider vinegar) I'm going to disassemble and clean the carbs thoroughly. What o-rings, gaskets, diaphragms, etc. should I replace? Where best to buy? Any opinions on the litter Vitron kits? Thanks.

First post and I'm afraid I'm asking for something. A little help. I'm the proud owner of a 1984 VF750F with about 45,000 to 48,000 kilometers on it (about because the odometer stopped working at 41,300 kms last summer and I've been riding). I was thinking it was good timing to do a valve adjustment on the bike. I've read a lot of posts here and other forms. I looks doable if you take you time and have some semblance of mechanical skills. I'm somewhat skillful and I don't mind picking up the tools that I needed over and above what I have. Sooooo ... I start by taking a look at things, noticed a coolant leak from one of the water pipes ... nice, now I know why I had to top up the coolant rather frequently. I order up all the bits I think I should need for the endeavour. They get here and I start doing my thing. I've taken my time with this as I have no need to rush it. At first I was thinking I could just reach under and pull out the water pipe after loosening the hose clamps. After ogling things for a bit I figured there wasn't enough room to do so. The carbs are going to have to come out. I wrestled them out ... I gotta tell you guys, holy f^c% are you kidding me???? Here is where the questions start. First with the carbs, should the "assembly" of all four carbs have some stability to it? Once I got them loose they are sorta hang'n together like there's some taught elastic allowing them to float around some. It certainly wasn't what I expected. Is that normal for them? Second, the valves were noisy. Not overly so, just with what I figure being 48,000 kilometers on the bike I should check them. I have two "service manual sources" one that says .005 the other says .006. I know that's pretty close but, almost all of the valves were way tighter than this. Less than .003 and only one that was .004. I thought I was measuring them wrong so I dug out the service manual and followed it through and double checked it all. They're all tight, I was expecting things to be "loose", meaning to me that I would easily slide .005 feeler gauge under them. Am I wrong in my thinking? I don't have anyone around to compare engine noise with. I haven't found any older VF guys in my neighbourhood just yet. All my riding buddies are more into newer bikes and when things get beyond an oil change they're challenged. Some thoughts. Some help. A few jokes. Anything to set me in the right direction would be appreciated. Cheers, Guy aka, canuk_guy

What's up guys! Unfortunately I sold my beloved VFR and crossed over to the dark side (Harley Davidson haha, what was I thinking)!!! I was cleaning out the garage the other day and I found a jet kit I bought but never got around to installing - I posted it in the classifieds but I figured I'd drop a quick post here if anyone wants it. I know for sure it'll fit the 4th Gen, not sure about any other models. PM me if you're interested, thanks!!

So I just finished cleaning the carbs on my 3rd gen VFR and I noticed there is fuel dripping out of tube #39 (see diagram below) at the top of the carb assembly. Obviously it's not running well. It's dripping out enough that it's leaving a pool on the garage floor. What the heck does this mean and how can I fix it?

I need to run a carb sync on my 1984 VF750F. Someone on here told me I could do it without removing the gas tank, but I'm having a hard time seeing how that could be possible. By looking through the side of the bike I don't see any vacuum nipples and I don't see how I could reach the sync adjustment screws. Any input appreciated.

Too much "looking into" is netting me conflicting info. Darn my need for thoroughness. The Tstat on my ride is kaputz, so I need to swap that out. Doing that required removal of the carbs. My bike has always smelled gassy. So while I'm at it, I might as well jet her properly, as I do have a K&N and a V&H slipon. But the more I look at stuff, the less clear it becomes. My first option was a Dynojet Stage one, but one source specifies for stock filter with slipon and another says aftermarket filter or aftermarket exhaust. The main jet size seems to be 124 or 126 (part #'s are D__124), different if you have a CA model. I do. It makes less sense because these are smaller than stock (seemingly). Maybe they are confusing 3G and 4G? Of course there are other options, most that seem to be less complete, although I'm not sure if its necessary. Things that I think I know: Stock main jets: 130 Stock pilot jets: 38 on CA model I have yet to open the bottom of my carbs (shame, shame) My bike was purchased in "stock" form, so my jets should be as well I don't know why she then smells gassy Things I would like to know: What kind of Keihen do we have? I want to look for options on Sudco. Jets are only $3-4. Does anyone have main jet/pilot jet, needle suggestions? Do I need new needles? I read a post suggesting it isn't necessary, just adjust height. Any and all advise appreciated. Thanks!

Hello new to the site, looks great! I have a 1986 750F has been in storage the last 6 years. yeah I know! I got a gasket kit 4 years ago just never got there. I started going through the carbs and all was looking good till I failed to notice there is a washer behind the spring on the air/fuel mix screw. I have one left. I can't seem to find this small washer. no help from the dealer- not available- only can find newer magna 750 kits with the whole screw kit for $23 or so. Anyone out there know where I can get this washer? I'd hate to pay 70 bucks for 3 washers. Thanks for any help Darin

So, I kind of touched on this on another topic I started about 2 weeks ago. My '93 VFR got a stuck float after sitting (w/ empty carbs) for 5 months while I was deployed. I got home June first and the float has stuck to varying degrees through 3 carb cleanings since then. I clean it, put it back together and synch the carbs and ride all day. Sits over night and the next morning it wont turn over. I'm really tired of wrenching and the next 6-8 months will have me away for the majority of the time so there won't be much time to wrench on it. I haven't even touched it since I put it all back together. Problem? Stuck float lets gas fill the combustion chamber (cylinder #3) and the next morning when you go to start it up it'll lock up the engine and no start. Easy fix really, just a little time consuming. I don't need the money but I don't need to be paying insurance and reg. on it when it's sitting. Also, the wife and daughter want a Grom or 250 something to learn on and my garage can't handle 3 bikes nor do I want to drop money on a bike when one is sitting in the garage not doing anything. Anyway, whats it worth? Here's the details. I found my VFR almost 2 years ago rotting away in someones back yard. Picked it up for $250 and started the resto. It had been sitting there for 5 years prior to me finding it so lots of time and work went into where she is today. Original color was white for '93 and this is what she looked like when I brought her home. The restoration pic. Mechanical stuff I'm decent at but I never did bodywork until I got this bike so it is not perfect. While everything is there and it looks great from 10 feet when you get up on it you can see where the plastic needs to be mended or where my painting skills/bondo skills suck. If I keep it I will be sending it to a pro and would probably drop $750 to make the bodywork/paint perfect. Otherwise, it has 38000 miles. I rode it about 8000 miles last fall (I ride alot) before I deployed over the winter. It has fresh plugs, filter, oil/filter I did two weeks ago. As far as what I did to it last year when I restored it here is the list. Full 2005 R1 front end (forks, wheel, discs, master, fender, wheel bearings and proper disc bolts) CBR954 triple with new Honda head bearings. (it brakes and rides perfect but due to the triple parking lot turning radius does suck but is doable) Fresh oil/seals and race tech 1.0k springs in the forks. Jamie Daugherty CBR954 rear shock re-valved and sprung for a 220lb. rider RK 530 gold chain shorty levers (black w/ red adjuster) Danmoto convertibars fully adjustable. (a little lower than stock clip-ons but still comfy) SS HEL front brake lines. UNI air filter Volt meter clock with air thermometer (battery operated gas station special) Ricks R/R VFRness (so there should be no electrical issues) new YUASA battery as of June 10 2013 new carb boots. June 2 2013 gas tank was cleaned and coated. All bodywork mended and painted (to the best of my ability) all decals are from www.xtreemedecals.com. New Airtech rear seat cowl. new starter clutch right side engine cover gasket Emgo mirrors Double Bubble dark tint wind screen. It had the Cobra F1 pipe (slip on) when I found it and it works. I also have a brand new Corbin ($440 new)and brand new Hepco Becker hard luggage mounts and bags ($890 new). But If someone wants the bike I'll probably sell those seperately. Both are new still in the box. I also have the complete front end with fresh oil and seals installed. Here's what she looks like as she sits. Honestly, I'm tired of fiddling with it. If I sold it years from now I'd probably regret it but for the next few years I won't/don't have the time and when I see it in the garage on the lift I get irritated. I have no idea what to ask for it and it would be worth a decent amout parted out.

While perusing the Durbahn site looking at all the shiney things that you couldn't buy if you sold half your organs, I saw their Keihin FCR carbs for the RC30. And well, that got me thinking. Carbs aren't that complicated. Surely less complicated to make a rack for carbs than convert to FI (as their NC30). There's a lot of information to go over, so who wants to help? For the point of the discussion, let's assume that there are no bottlenecks in the system, and ignore jet and pilot settings. I just want to see what it would take to get a set of flat slide carbs on. Not that I'm planning on starting another project any time soon. Durbahn advertise a 7hp gain just from switching the carbs from the OEM to the Keihin FCR39s for the RC30. What is giving the extra power? Jetting can always be adjusted and tuned, so it has to be something more than that. What are the sizes on the intakes for the 3rd and 4th gen. I think they are different. 3g=39mm. 4g-41mm? I can always check my 96 carbs for the size, but not the 3rd gen. What are they on the RC30? Does Keihin make an individual carb unit so that 4 units could be assembled and mounted in the orientation needed for the VFR?

A few months back, had posted on here my '96 VFR's running issues. The issues of not completely running smoothly when trying to maintain throttle at certain speeds, nearly always in the 1/8 throttle open or less. Last couple weeks, basically returned the bikes carbs back to OEM (had put in a jet kit). Bought new main jets and pilot jets and put them back in place of the jet kit sizes. New float needles as well. Carb was fully re-cleaned of course to make sure prior to bolting everything back together. New OEM air filter put in, instead of the K&N. Airbox with snorkel in put back in place of the de-snorkled. Fuel pump is NOT OEM though, as I had installed a Facet one (correct one to match required specs: model Facet 40171) Only have a Delkevic slip on exhaust. Fuel/air mixture screws are turned out 4 turns total. Yes, I know this is probably way too much... but if not, the issue seems even more noticeable if screws were turned out 2 1/2 to 3 turns. It's only is this throttle position is this what I am experiencing. Is there something I'm missing that might need replacing? I've pretty much replaced all the carb guts except floats and new diaphram/slides. Would there be a possibility that the (using the microfiche name description) part no. 16510-MZ2-650 VALVE ASSY., AIR CUT may need to be replaced or bad?? Can't think of what else is causing this. New carb boots, vaccum lines, new nipple end caps too. Checked fuel coming out of petcock... flows out really fast. New fuel filter, spark plugs are new again and from past post... pretty much all new everything electric, from stator, rec, pulse coils... you name it, it's been replaced new. Any suggestion for this possible low circuit issue or worse, would be greatly appreciated.