Carb throttle valve

snoosky

XS650 Enthusiast
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Hey all.. After some strange noises and pops from my bike on one side, I pulled the carbs and noticed one of the vacuum slides (aka throttle valve, aka diaphram assembly) seemed to have gotten twisted in place. When I removed the top to reseat, the rubber seems stretched out and does not want to sit back in its groove properly.
Soooo.. after extensive searching, I cannot find this part on any cycle parts site, Yamaha or XS650 parts places. .. Anyone have a line on these or have an NOS around they could part with?
From my research, its part number 22V-14940-00-00
79 XS650 2Fo
BS38 carbs
 
The '78-'79 type slide/diaphragm assembly is pretty hard to come by. If yours isn't torn or it doesn't have any holes in it, you may be able to get it back in place by using some red rubber grease. I apply it to all my diaphragms now, and I put it in the groove they seat into as well. I think it helps them seal, besides preserving and softening the rubber ,,,,,

DiaphragmGreased.jpg


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DiaphragmGreased4.jpg
 
Thanks for the replies. I always go with the cheapest options first and work my way into what absolutely must be done. Haa! Those from NRP would probably end up being over $100 with shipping to Oregon.. Ouch...
 
I replaced my diaphragms with parts from JBM industries, they're originally an aircraft parts manufacturer and still make their parts in house. They seem to work well, and they have a bunch of information regarding disassembly/assembly on their site. Here's a link:

http://jbmindustries.com/diaphragms.html

looks like they run around $20/diaphragm
 
That's a pretty helpful site. Guess I didn't realize the slides twist around on the diaphrams so much. . A little super glue seems to be the hack for that.
 
Well yes, those aftermarket JBMs can move on the slide. Originals don't. There are original type replacements out there, but I haven't figured out how to put them on, lol. The originals are trapped very tightly on the slide between two plastic rings. You cut those off when fitting the JBMs. If I can figure out a way to spread those plastic rings enough to get the old rubber out and the new one in, I'd be all set, lol. Those original type replacements can be had quite cheap.
 
That's a pretty helpful site. Guess I didn't realize the slides twist around on the diaphrams so much. . A little super glue seems to be the hack for that.
Yeah, it's an odd problem, Im not sure what's applying a torque to the slides to cause that. Just vibration between the slide and carb body?

...The originals are trapped very tightly on the slide between two plastic rings. You cut those off when fitting the JBMs. If I can figure out a way to spread those plastic rings enough to get the old rubber out and the new one in, I'd be all set, lol. Those original type replacements can be had quite cheap.
It's been a long time since I had hands on the originals, do you think they were over-molded on to the brass at the factory? Or is that brass lip rolled over the plastic rings to clamp them together?
 
I think it's the 2nd thing, the top edge of the slide rolled over to clamp the rings in place and together. I've got some ideas about building a little spreading jig, something to spread the rings apart or open a little so I could get the old rubber out and the new rubber in. I wouldn't remove them, just pry them open enough to change the rubber.
 
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