Mystery problem with starter switch

I'd caution against buying a kit. You'll need new bowl gaskets and new insulator boots (and maybe something that I've forgotten like o-rings for jets?), but you won't really know what you need until you're in there. The diaphragms and cutoff valves are not cheap, and all eight sets of mine were in fine shape.

And I'd buy factory parts, except you could get away with aftermarket bowl gaskets. I don't buy new jets unless something is actually wrecked or wrong. Use plastic or copper wire or something soft to unplug them so you don't damage the passage and jets will clean right up. I have personally had great luck using jetsrus.con for parts for both STs and my mid-70s CB carb rebuilds. If you don't see something, ask him.

This was my first of two sets of ST carbs I rebuilt: https://www.st-owners.com/forums/threads/carb-cleaning-questions.174149/ I'm just a guy in my garage, but the bike has run fantastically since.

I don't think I'd bother doing the Canadian jetting that I did unless maybe you've got the hotter cams I understand the early bikes had. I didn't really notice any difference but mine is a '96. I'd strongly suggest the cooling lines/elbows/o-rings while you're in there. It's not hard to get in but it sure takes time as you know. Blow a line and you're calling for a tow..
 
claytonia said:
Anyone have recommendations for source/brand of rebuild kits?
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The guy in the below link has a good reputation for rebuilding Honda V4 carburetors. The ST1100 may not be listed on his site, but he does do them. He has done them for several people on this forum. From what I understand, you can either send the carburetors to him and have him do the rebuild or you can buy the kits and parts from him.

Billy Carr in Canton, TX
 
Thanks ! I've printed out the carb rebuild instructions - extremely thorough and clear, and undoubtedly helpful.

I will definitely pull them and disassemble before ordering anything.
 
OK so success on the charging front - I replaced the regulator and started it up (still on 2 cylinders), and the battery voltage started increasing (from 13.1 to 13.9, in the first few seconds). At least I think that's a good indicator - before it would start running down every time.

But I still have the other problem. I had already bypassed the fuel petcock (see photo), which had no effect, and today I bypassed the fuel pump (see other photo), which also had no effect. I'm thinking even more that it's time to rebuild the carbs. Other shots of the plugs after running for a couple minutes (still unable to get it much past 4K rpm). These are new NGK Iridiums (as of the current problem), so not much buildup to see. But they all came out wet. And last time I checked they all had spark.
 

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Make sure you have the correct size JIS driver before you go digging into the carbs. The screws are soft and can be pretty tight, and a phillips will just wreck the heads.
 
Smudgemo said:
Make sure you have the correct size JIS driver before you go digging into the carbs. The screws are soft and can be pretty tight, and a phillips will just wreck the heads.
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Yeah, sounds like a good idea. I'll see if I have a bit that will work. Thanks!
 
Make sure and add the fuel filter back into the circuit BEFORE installing the newly cleaned carbs, you don't want any crud in there. I would seriously consider emptying the Tank and getting fresh fuel in there as well.
 
So those bits are pretty expensive. Anyone know what size JIS bit is needed for these carbs? I've never run into this issue on numerous other Japanese bikes I've had - at least not serious enough that I couldn't get the screws out.
 
Slydynbye said:
Make sure and add the fuel filter back into the circuit BEFORE installing the newly cleaned carbs, you don't want any crud in there. I would seriously consider emptying the Tank and getting fresh fuel in there as well.
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Thanks - good suggestions. I have a new fuel filter, although not sure where the old one is.
And hey, I have that same Italian poster in my garage!
 
So I'm almost done cleaning the carbs. I feel like this is not going to do it. They were relatively clean inside, nothing blocked so far - nothing that I would attribute to how crappy it's been running.

One question - I've seen mentions of bypassing the fuel petcock, for diagnosing but also seems like some say it's OK to bypass it permanently. Is there any consensus on this? Mine looks in pretty good shape, but I'd rather not reassemble it if I can do without. I would not have thought this was a good idea, but I've seen a few posts/comments indicating it is.
 
The vinyl/plastic/whatever diaphragms and cutoff valves were all in good shape? Torn or non-functioning is an issue according to the write-ups. Mine were fine, so I don't have any experience.

Removing the vacuum valve permanently has been tons of times but I think there are people in both camps as to whether you should. Mine is in a box in the attic and hasn't been missed, but I'm also not sure I'd pull it again if I started over on all the work I did.
 
claytonia said:
One question - I've seen mentions of bypassing the fuel petcock, for diagnosing but also seems like some say it's OK to bypass it permanently. Is there any consensus on this? Mine looks in pretty good shape, but I'd rather not reassemble it if I can do without. I would not have thought this was a good idea, but I've seen a few posts/comments indicating it is.
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Bypassing the vac. fuel valve is about a 5 minute job. Don't forget to plug the vac. hose. Bypass it and when the bike is running right, hook the hoses back to stock.

I have run many K miles without one but it is your decision.

If you decide to keep it, be aware of how to bypass it. I've done 3 on the side of the road. Not an act I would promote but you do what you need to get moving.
 
So before winter temps hit I pretty much gave up on it, as it was running so poorly, with one cylinder clearly missing. I just had the feeling I missed something pretty obvious because there's good spark, fuel delivery, and compression in all cylinders. Checked the vacuum hoses, etc. (but...see below). So I bought a new Yamaha Tracer 9 GT (fuel injection! ABS! Traction and skid control!) - which will be my all purpose sport-tourer now. I was just wishing the ST went away - although it's a beautiful, low mileage, comfortable ride - I find myself no longer enjoying working on my bikes (at least with these types pf problems). But then something hit me - in bypassing the petcock, I don't recall plugging the vacuum tube that operated it. I'm looking at my last message from Ron, above: "Don't forget to plug the vac. hose"! OK...so my question is, where does this hose connect (to the #3 carb I think I saw somewhere)? I've been looking all around that area and see nothing disconnected. Can someone maybe suggest what I can do in about this? I'm pretty embarrassed, as I usually make notes and label everything during disassembly on jobs like this.
 
Clay, just a suggestion:

With the title of this thread, you may get a better response starting a new thread with a descriptive title.
 
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