Aftermarket CV carb diaphragm replacements - anyone tried?

Re: Aftermarket CV carb diaphragm replacements - anyone trie

Hi Again,
Just got the JBM diaphragm replacements yesterday and I just had to try them out.
They are damn supple and nice and snug when stretched over the piston, but not too tight as to deform or anything.

Really impressed with the press in fit to the top groove of the carb too. All round impressive and great product, me thinks.

I used the '3' in the '73' on the top of the diaphragm mold as my marker and made sure the diaphragm was on the piston in the right spot by sliding it around while gripping the tyre.

Cutting the lower plastic ring off was a bit tricky, compared to the top one, but I just took my time and worked a groove into the edge before snapping it off.

Mountain of pics below,

 

I got mine re-done at NRP in the UK http://www.nrp-carbs.co.uk/

Did a beautiful job, good service too. Not as cheap as these at 32 GBP each plus P&H.

Cheers Ian

 

Re: Aftermarket CV carb diaphragm replacements - anyone trie

I'm seriously considering these jbmindustries diaphragms as well for my '81 XJ650. Anyone else have any experience with them?

 

Okay, I've got the diaphragms installed (super fast shipping, by the way and Don even sent a replacement when one of the originals was damaged by a staple used to package them). Installation was easy and the bike runs like a champ (or at least without any problems related to the diaphragms).

Now it's just a matter of time to see if they'll last, but I don't have any reason to believe they won't.

 

Fitz, The Maxim-X 700 and 750 have Mikuni BS33 Carbs

 

Re: Aftermarket CV carb diaphragm replacements - anyone trie

Ditto Ditto Ditto!!! Even the pics could have been mine.

They arrived fast, installed easy, very impressed.

 

This dude is making something similar.

Was looking into it when i had an old gpz 600 r with carb issues.

http://www.cameron-site.co.uk/nrp/index.htm

 

I just wanted to follow up and let everyone know I've had these jbmindustries diaphragms for a few months now and not had a spot of trouble so far.

 

alrighty... looks like we are 8 years down the track... which seems insane! but never the less.
I have 2 bikes and this means it is not really that many years worth of on road use.
I have run into the issue that the JBM diaphragms are quite loose on the slides now and the slides are rotating... so far 90 degrees plus on all 4 carbs.
I have fuel on the upper part of the diaphragms also so...
I've moved my floats to the maximum of 6mm and I've decided to anchor the diaphragms in with a layer of RTV. I will post the picture tomorrow and keep you updated on the outcome.
Disappointing hopefully the RTV fix will be the answer!

 

use a fuel resistant rtv

 

I don't know how long JBM has been around, but he's had the XS650 covered for a very long time. The newsletters, forums, e-groups all praise the product. I have never noted a negative remark on JBM.

 

Anchored them with ThreeBond RTV last night. That'll solve it! (I hope)

Yes the diaphragms themselves are great, no doubt, but I have been having this crazy stumble after the bike is hot and I reckon this maybe the cause. I will find out later today of course.

My fix...

 

I think the issue with the diaphragms is more of a flooding issue and ending up with fuel in the chamber above when hot.
Trying to solve by going backwards.

Dropped the fuel level to +1 (6mm).
Putting original needles and lowering by one notch for a test tomorrow. (I had put a kit through and the replacement needles are brass so back to the original aluminium)

The RTV looks great after the test ride today with better (crisp) response but after warming up... back to the serious stumble. (as in pushing off like a bicycle with the bike trying to throw you off once the fuel has cleared)
Fingers crossed... again!

This engine is 1oookm+ after being freshly bored and is not standard (58L pistons in a 31A bore) so... good fun! (grrrr.)

 

RTV was rubbish.
This looks good. At least I have the diaphragms not moving around, not that that was or is the real issue I have. Oh well.

 

Do you think a replacement support ring under the bottom would help keep them stable? I'm looking at possibly ordering a set if available for the bs28.

 

Just to clarify.
The diaphragms are not failing.
They are actually just like new still.

The issue I have is not related to them at all but I did overly state the problem with the slides rotating over time as being the reason I have the problem I have.

The pictures I attached a couple of posts up show a dot (wet spot) where I've glued them with Rapidfix glue to stop them from spinning.

Disregard my previous angst. I should have actually created a new post about the issue I'm trying to resolve.
If I do resolve it I will.

But, I wouldn't hesitate in purchasing the JBM diaphragms. Best thing since sliced bread.