82 GS750T, Please Help!!

[Flyboy]

No, if a coil goes bad, the coil goes bad, there are not two halfs per se, in these bikes the coil fires both 1 and 4 or 2 and 3 at the same time, it is a lost spark arrangment, in other words, when it is time for cylinder 1 to fire, the coil fires both 1 and 4 at the same time, same with 2 and 3.
I doubt your issue is coils.You mat want to check plug caps though, you may have two dodgy caps there, they are cheap enough to replace.

[Big T]

Since all 4 cylinders run, even badly, you're going down the wrong way looking at the coils/ignition. Your bike ran great last year, then sat for months. Yes, the carbs can clog up that fast

I don't care if those bozos said they cleaned your carbs- what you are describing is clogged low speed circuits and/or a really bad sync

Did you get your sync tools yet?

Flyboy is correct - a coil is either good or bad, so that's not the problem

Go down to NAPA or Autozone and get a can of carb dip and do a carb clean yourself. Don't forget new O rings. Go back to post #2, read your BassCliff 10 things and the carb cleaning page and once you've done all that, you should be good to go

[mjremington]

No we havent got the sync tool yet. We're waiting for it to come. My buddy who is helping me and who's garage it is in right now is ordering one since he works on so much stuff he figures it'd be nice just to have one. So when that gets here we'll start there.

But even last year cylinders 1 and 2 wouldn't pick up for a long time while starting and warm up. But eventually they would pick up and stay going. Is there an internal settings with the floats,needles, jets inside the carbs that could cause them to not get fuel but then pick up? We're gonna go thru all the check list stuff as well. I appreciate all the insight. We'll get it. So I'll start with the carb cleaning, sync, valve adjustment and go from there.

[Flyboy]

So I'll start with the carb cleaning, sync, valve adjustment and go from there.

Now you on the road to GS happiness, don't forget to keep us updated along the way, I will be following this one, can't wait for the post saying the first start up was flawless.

[Guy]

Your problem is not ignition related, it's not a carb sync issue and it's not a valve clearance problem.
Start the bike, kneel down beside it, remove the small (vac) hose from the carb end (block the vac port on the carb with your finger), suck on the vac hose for a few seconds.
See?

[TPL]

Seems obvious that you have clogged circuits in your carbs, have fun and good luck with it.

[mjremington]

Guy, what are you saying I'll find by blocking the vac valve on the carbs then sucking on the vac line attached to the tank? Are you thinking I have fuel coming in through the vac line? I rebuilt the petcock last year. Just not sure what other then that I should be looking for during that "test".

[mjremington]

And that would explain #2 being finicky but would it also explain #1 as well? That is if thats what you believe my problem is.

[Guy]

I believe the problem is fuel starvation and manual stimulation of the petcock diaphragm should start to tickle the two empty carbs. Is there a prime position on the petcock? Check you're fuel delivery in any event.

[mjremington]

Ok, that makes sense. We'll have to try that. Yes there is a prime position on the petcock. I used prime to start it for the first time because we had the tank off and had drained all the fuel from the system. But when she fired we turned it back to ON/RUN. So if I manually cause vacuum pull to the petcock and then cylinders 1 and 2 fire on start up with 3 and 4 like they should. What is that showing as the cause? Bad petcock? Or dirty carbs? We plan on cleaning the heck out of the carbs as shown in BassCliffs page and redoing a sync. But if there is a possibility that the petcock is bad I'd just buy a new one as it was rebuilt last year and I'd like to completely remove any variables. New they're like 75 for OEM and 50 for aftermarket.

[mjremington]

Can poorly adjusted mixture screws cause fuel starvation as well? I'm just trying to check all the bases because the shop that had my bike last year took forever and they didn't do the best of job obviously. And I know what they said they "did" but who really knows.

[Kcwiro]

- Petcock rebuild .... I just flat out replaced my old vacuum one with a pingle manual one. As long as you remember to switch it off after each ride you are just fine and you get a reserve to boot... somethings you should seriously just pay the extra $40 for...

- First sync your carbs and make sure they are set correctly

- the fact you have a two cylinders firing at a later point says sounds like you could have stuck floats... can try the lazy approach and run some seafoam through a tank of gas

- do not trust a shop to touch your old bike it is a money pit since most guys there will not know what to do on these old machines anyway.... if they took 4 months for a carb sync should tell you enough... I took my head and block for re-machining and basic adjustments while I worked on the rest of the bike that and change the old screws out on my bike. I also had them do my first valve check and sync... after that all by my own hand stuff.

- not much else for us to say about this until you have disassemble your carbs and dipped them.... use that time to repaint them up nice after your done. It really sounds like the shop did a **** poor job if anything at all.... carb stuff is easily covered in the book and on many guides here follow that do it yourself and you should be golden.

- Also I suggest you remove the inline fuel filter there has been starvation issues brought on by those given our bikes are gravity fed....

[mjremington]

Will messing with the idle air/fuel mixture screws mess up the sync of the carbs? Are they one in the same? The sync tool should be arriving shortly but my buddy wants to play with the mixture screws. I'm apprehensive to say the least. He wants to check where 3 and 4 are and compare 1 & 2 to that to make sure they're all the same. Is there logic in his thinking? Also, I was under the assumption that my bike was vacuum fed(unless on prime or reserve)? So would an inline filter cause starvation to the closest carbs but not the farthest ones? The reason it's there is because the petcock screen is gone. I greatly appreciate everyone's feedback, ideas, and tutelage. I probably wouldve just sold the bike due to my frustrations. I'll update as the work continues and/or more questions pop up.