Jump to content
Sign in to follow this  
YoshiHNS

4th gen Carb Vacuum Pistons Group Buy

Recommended Posts

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.

 

KEIHIN-4-216x164.jpg

 

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. 

29. 

30. 

 

 

@kgsmotorcycles @Dutchy @mcrwt644

  • Like 1

Share this post


Link to post
Share on other sites

 YoshiHNS,

 

Count me in for one (1) set.

Share this post


Link to post
Share on other sites

I'll put in for a set.

Share this post


Link to post
Share on other sites

I'll be in for a set as well.

Share this post


Link to post
Share on other sites

Bumpity bump.

 

No other 4th gens want some fresh rubber in their fuel control system?

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

I no longer have a 4th gen, but if I still did I'd be all over this one.  Nice job! 

 

Share this post


Link to post
Share on other sites

If you haven’t already placed the order, I’d like a set. Don’t need them yet, but know I will sooner or later, and I might not get another chance. 

Share this post


Link to post
Share on other sites

Missed this post.....   I no longer have redslut, but have cross posted this on the dutch VFR forum.

Share this post


Link to post
Share on other sites

Can you add me for a set too please? Thanks



Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

I would like 2 sets, please.

Anyone got an electronic manual for these Keihin carburetors that discusses jet sizes etc.? 

I have the '96 shop manual.

Any idea if these diaphragms are the same size as used in the '86 750?

Thanks for putting this idea together !

Share this post


Link to post
Share on other sites

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.

http://jbmindustries.com/Dimensions.html

Share this post


Link to post
Share on other sites

Hey, 

I can be in for a couple sets.. I'm due for a carb rebuild and will need these, i'm sure. 

keep me posted on what happens! 

Share this post


Link to post
Share on other sites

Update.

 

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!

Share this post


Link to post
Share on other sites

Good news. Thanks for staying on this for us. 

Share this post


Link to post
Share on other sites

Yoshi,  I am currently in for 1, increase it to 2.

 

Share this post


Link to post
Share on other sites

OI don't know if this helps, but looking at Partzilla, part number 16111-MZ1-000 is the vacuum, pistion for the '94-'97 VFR750F and '94-'95 CB1000A.

Share this post


Link to post
Share on other sites

Just saw this....been really busy....what is the status of this?  I would be in for a set.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×

Important Information

By using this site, you agree to our Privacy Policy.