83 cb650sc carb options

[tockey]

By way of intro, I'm an experienced wrencher on cars and trucks gas and diesel. Completely new to motorcycles. This is my first bike and I've never ridden as it's a project. I got a project bike for personal reasons. I may get another bike to ride this season that's not a project but that's a different topic. I intend to restore this bike to safe reliable runner not show queen.

In rebuilding carbs I've noticed a few splitting intake boots and a few slide diaphragms with pinholes and one torn. The rubber also seems shrunk and doesn't want to reseal between main body and cap well. While struggling to find parts, I noticed Murray's dual Mikuni VM34 retrofit setup and thought that's pretty tempting.

I don't mind the cost because I'm financially irresponsible, I don't mind originality because I'm not a collector, I don't mind tuning needing redone after it's running with my eventual exhaust plans because I like to tinker, I'd ditch the pods and fab something to plumb them to oem airbox because I prefer that.

Is this a horrible idea? Should I chase down and shell out for VE54A parts? Doesn't it seem better to retrofit to something that's more serviceable and potentially runs better?

Thanks for any advice folks

[Pete in PA]

No experience with Murray.  I do have experience with CV carbs on several bikes.

CV carbs when tuned right give great running from idle to redline.
Better than FI.

Me, I'd get whatever the stock carbs need.

[mollusc]

I believe the Murray's are specifically designed to work with pods -- that's the line that I see being touted by every podfan anyway.  So if you're planning on keeping the original airbox I would stick with something close to stock for the carbs.
The '83 CB650 is the same as the '84 and the '85, so you could look for a set from either of those years.  Any 29mm CV carbs should work though.

[tockey]

I found a seller on ebay who's listed diaphragms only. I removed one from a slide and tried to reinstall it lubed with soapy water but I feel like it'll rip before I get it seated. Is there a way to release the plastic rings or a trick to installing the diaphragm to the slide?

Separately, there is a company called JBM Industries selling aftermarket diaphragms that require cutting the plastic rings off. Their diaphragms have a thick undersized ID they call a "tire" to seat and seal against the slide. Anyone have experience with these?

[tockey]

I believe the Murray's are specifically designed to work with pods -- that's the line that I see being touted by every podfan anyway.  So if you're planning on keeping the original airbox I would stick with something close to stock for the carbs.
The '83 CB650 is the same as the '84 and the '85, so you could look for a set from either of those years.  Any 29mm CV carbs should work though.

I feel like another set of 40year old carbs is liable to have the same issues. I prefer to just keep it original if I can find or repair the slides. My carbs are otherwise in very good shape.

[Bob H]

... JBM Industries selling aftermarket diaphragms that require cutting the plastic rings off. Their diaphragms have a thick undersized ID they call a "tire" to seat and seal against the slide. Anyone have experience with these?

No, but I would be willing to consider them. I spent a fortune on OEM diaphragms last year, JBM was one of the more respected alternatives I ran across in my research.  They have been around a long time and have pretty good feedback from what I read.

[Pete in PA]

Check a few Youtubes on diaphragms.  There are 2 or 3 systems to replace them. You either break off those rings or you don't.

No experience (yet) But I'd go for the way where you leave the rings alone. You want to leave the total weight alone, it affects lift and drop speed.

[mollusc]

Any 29mm CV carbs should work though.

I feel like another set of 40year old carbs is liable to have the same issues. I prefer to just keep it original if I can find or repair the slides. My carbs are otherwise in very good shape.

You can probably find a much younger set from a different bike.