JBM Diaphragms

[fnickel]

Got a problem with BS38 diaphragms. I installed a set from JBM about a year ago. Within a week, the slides started rotating within the diaphragm, making it run bad. I used the best silicon adhesive (fuel resistant) that I had to glue the surfaces between the slide and diaphragm. It last about a year, and the same thing has started to happen again. Any recommendations for a permanent bond between the slides and diaphragms?

Also, I now have a tiny pinhole in one of the diaphragms near the outer edge. Is there any material or goop that I can use to patch this pinhole, or am I stuck ordering another diaphragm? Thanks for your help.

 

[fullercameron]

I had a rotating slide after I installed my diaphragms as well. I called and talked with the guy at JBM and he was very nice. He said that he doesn't think that they should need adhesive but that if it seemed necessary that he would use a drop of super glue.

I used the super glue about six months ago and no problems. I posted here and it seemed like others had had issues with rotation as well. Some of the other members here said that the slide rotation (although it could be cured with super glue) was likely caused by something small stuck to the inside of the carb body creating turbulence in the airflow and making the slide move.

You might want to check and see if there is anything hanging the slide up, etc. in the carb body.

As for the pinhole, you might talk with JBM and see if he has any suggestions. Like I said I have spoken with him a couple of times on the phone and he has always been pleasant to deal with.

 

[cros36]

yup, i used some super glue to keep mine in place. they were rotating. theres a thread on here about it somewhere. seems that it happens a bit.

i would buy them again tho. sorry to hear about the pinhole. maybe he will hook you up. super nice dude.

 

[XSLeo]

From some of the reading I have done on the slides turning is becuse of a rough spot from varnish build up on the slide and/or in the slides bore. Often so small you can't see it, but can feel it.
To remove this rough spot, feel with a finger tip to find, then use a rag wet with carb cleaner to clean the rough spot off.
Clean, feel repeat as needed till you can't feel the spot.
Leo

 

[fnickel]

I ended up using a product called Seal-All. It is an adhesive/sealant in a bright yellow tube, available a lot of different places. It's advertised as fuel and oil resistant. I heard that Crazy Glue dries to a hard brittle finish, so I thought I would try the Seal-All. It seemed to work well. Goes on like contact cement, apply to both surfaces, wait about 5 minutes and then assemble. It costs a little more than Crazy Glue, about 5 dollars for a tube, but I thought it was worth a try. Regarding the rotation of the slides, my best bet is that it is due to the vibration of the engine. These engines to vibrate a lot, and strange things do happen as a result of that vibration. Just try revving up the engine while on the centerstand, and you'll see the bike start to walk. Anyway, thanks for your help on this. If anything else develops, I will update.

 

[XSLeo]

I like Seal All. You can fix a hole in a gas tank with Seal All and a stiff piece of paper, evden with gas running out. A good heavy coat of Seal All spread on the stiff paper, place over the hole, hold in firmly in place. After a few minutes the Seal All driesz enough and the gas stops leaking past the paper, it's fixed.
Not a permnent fix but should get you home. Then fix it properly.
On the center stand and walking, that was the first Japanese bike with reverse.
Leo