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.
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.
maybe interested but wondering about postage to the UK, on the TV this morning they said the UK £ was worth 1.28 US dollars, thats a shit exchange if you just off to the states for a holiday
I'm in! Bought a set of carbs last year for parts but the rubber parts wont last forever. Owning 20 plus year old motorcycles you have to plan ahead. Thanks for thinking ahead and setting this up. Hope we get enough orders to make this happen.
AFAIK, they are not the same. These pistons are only used in the 4th gen VFR. That is by going off of part numbers in the parts catalog.
He might have one that fits. that might be the same as the VF700C, which he has listed. K-68. Send an email, pictures, and dimensions, and he should be able to let you know.
Been discussing with Billy C (V4 carb rebuilder). He is in for 10 sets if he can be convinced that the replacements will work. We've been looking at different things, and think we've found that CBR900RR and CBR600F3 (among others) share the same diaphragm. We are going to see how close F3 pistons are to the VFR ones. If they are similar, this opens up a bigger market for JBM industries to serve. We are just on the borderline of making the 30 minimum order, so this might be a reality after all!
Status is Billy C found that the CBR piston assembly matches with the VFR one. That's about it. I'm working extra this week and hope to get back with him on getting one of this destroyed diaphragms into the hands of Paul, so he can give a final ya/nae on making them and how he would make them. Pretty sure with opening the group buy to CBR600, 900, 1000, we would have no problem breaking 30. We're only a few short now anyways.
I contacted the guy a long time ago now and mentioned the order numbers I had and that they would also fit these other bikes, increasing the order size, and never heard back.
End of thread · 25 posts recoveredWayback Machine snapshot 6 Dec 2019
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