Intake boots

[Robyle3]

Suzukian those are exactly the ones! Also did a search for possibly restoring the rubbers since I wasn’t having any luck. Found an awesome video about restoring old rubber parts using wintergreen oil as a few have suggested!

[Suzukian]

Cool, I have never seen them listed before. You know how EBAY is, you see one, then they are gone, then a week later, you see a bunch of them. Those were in really good shape, but expensive. I would check the o-rings on yours first. If you see cracks in yours, then get the EBAY ones, as yours will leak in a matter of time. If there aren't any cracks though, I don't think they would be the source of a leak (through the sides).

[Robyle3]

FWIW, the o-rings always go before the boots. If the OP's boots are still relatively intact (not cracked, peeling off, shrunken, or missing chunks) perhaps replacing the o-rings would kick this can down the road a little longer.

Photo is the condition of the boots as they are currently, couldn’t squeeze my phone under it. They are both the same. Was wondering if I could cheat the system by putting a thin layer of high-temp calliper grease esp at the carburetor joins?

[Suzukian]

If the bike is running, you could spray some starter fluid (use the little thin red straw on the spray can tip, to pin point where your spray, most automotive shops sell packs of 10 of them) get the bike idling, the spray at the intake boots at various spots. If there is a leak, the bike will immediately raise it's idle, if nothing happens, then they aren't leaking, and don't touch them, they could stay like that without leaking for another 20 years. My '83 GS750ES has the original intake boots on them. I had the carbs off just last week. The boots are the original ones that came on the bike when I purchased it new.

[Robyle3]

Debating on if I should start a new thread for this, but I thought it would be appropriate here, since I am suspect that the intake boot might be part of my issue.

But my bike just does not want to idle, especially in the mornings when it’s a little colder. on first start, I always have the choke in, and predictively the RPMs shoot up to about 4000. I fiddle with the choke lever to manage RPMs while I put on my gear, but when I reduce the choke to about half, RPMs take a dive in the bike dies. And aside from starter issues that I know are not related at all to fuel air mixture’s, I usually have to open the prime circuit on the petcock to have enough fuel to start.

Suspecting it may be a battery issue as well, but once the bike is warm it idles at 1500 with absolutely no problems, until I ride around for a good 15 minutes, when the idle creeps up to about 2000 to 3500. I’ve played around with the idle adjustment, and having it too low forces me to use much more choke before I hop on and ride. This happens regardless of whether the battery has a fresh charge or not, so I’m not entirely inclined to say battery issues. Wondering if an air leak somewhere is my main culprit, also asked a buddy about the idling issues, and he suggested float levels might be off.

[Suzukian]

My '83 GS750ES is so cold blooded, when I purchased it, they told me to get used to running it with the choke on a long time. They weren't kidding. I lifted the needles one notch, and that gave me a lot more midrange, but it's still a cold blooded animal. Once very hot, it's no longer an issue. I think it's normal for bikes of that era.

[Robyle3]

That’s reassuring haha. Honestly one of the things I love about old bikes is how they have characters like this. Needs just as much go-juice as I do in the morning haha

[Suzukian]

It's good to know. That way you don't go chasing something that isn't broken.

[rphillips]

Lots of us local folks went up one size, from stock, on the pilots, to help the cold starts. Some say it won't help, but for us it seemed to make it noticeably better. I've raised the needles on a few, but mine never had notches, had to put shims under them, that was for mid range, I don't remember it changing the cold starting.

[Suzukian]

If it's really cold, I just pop off the seat, and the bike will start very quickly with a hand over the intake, once running, you can even rev and do that till the bike gets warm, and need no hand, seat popped back on, and I'm on my way. The needles worked shimmed worked for mid range, but these are cold blooded beasts.

[Robyle3]

If it's really cold, I just pop off the seat, and the bike will start very quickly with a hand over the intake, once running, you can even rev and do that till the bike gets warm, and need no hand, seat popped back on, and I'm on my way. The needles worked shimmed worked for mid range, but these are cold blooded beasts.

Good thing the seat is soo darn easy to get off!

[Robyle3]

If I’m chasing air leaks, am I mainly looking on the intake or engine side of the carbs? I just had a thought that the intake will only intake soo much, but the engine side and the intake manifold boots are where extra air would come from. Am I thinking about this too much or am I on to something?
Appreciate all the help soo far from you guys here! Bike is parked while I get the starter rebuilt, so have time to do more research.

[KiwiAlfa156]

Engine side is the high vacuum/fuel-air mix side. So air leaks here upset all the good work your carbies have done. Air leaks upstream of the fuel metering is comparatively low vacuum so a small leak here is unlikely to affect carburation.

[Robyle3]

Hate to leave anyone hanging on this, but I found a temporary solution! I was going to push the carbs back just enough to take the intakes off to soak them, when I noticed they were still supple and the carbs slid out very easy. Taking a can of silicone protectant (has chemicals known to slightly swell rubber), I DOUSED the boots in spray and tightened the clamps until my screwdriver almost started to slip. Ideally I’d let it soak into the rubber over the afternoon but out of curiosity I tried to start it.

Needed full choke but it idled perfectly at 1500rpm, and once it warmed up it bounced up to 2500-3000rpm after a minute or so. Dropped the choke and blipped the throttle and it settled around 900-1000rpm. Idle also doesn’t hang NEARLY as long as before. I’ll adjust the idle screw after work but it turns out that tightening the boot clamp was all that was needed in my case! At least now I have the solution required to refurbish any other rubber parts around the house haha.

[Robyle3]

Turns out I was too optimistic this afternoon haha. Took it out for a short run and it was still shooting up to 3000. Though now that I know the rubbers still have some life in them I am turning my eyes toward the carbs. I made an attempt to take the boots off after work and the starter plungers were filthy and coated in gunk.