carb or ignition trouble?

[Anonymous]

Hi Folks, newbie here. Great forum and resource keep up the good work!

I'm working on a friends 1983 GS750E. He drove it into his garage in '97 and let it sit until last year. He was having problems with the charging system and lights so I replaced the voltage reg & stator. Previous to that change he had a local garage clean the carbs. They said it was running but I don't believe them. After the reg & stator change I tried to get the bike running here's what happens:
Bike starts on full choke, idles off choke but almost seems like on only two cylinders. Mufflers are cold. (#2 &4) When gas is given bike dies.

I'm a little stumped. Search the Tech area and I believe it may be the diaphram but could also be ignition. Checked coils they seem to be OK, spark is good, doesn't look weak. Is there any real way to tell!

Thanks

[nabrams]

If all plugs were sparking then it can only be two things:
1. Carbs 2 and 4 are still a bit dirty - multiple cleanings are sometimes necessary because you miss some stuff the first time.
2. You have air leaks somewhere (anywhere from the air box to the exhaust pipes) - These bikes are EXTREMELY sensitive to air leaks. See my other posts on this topic.

[Anonymous]

I agree about the air leaks. I don't know what stage of repair you're in, but the bike won't run right without everything in place and sealed up right.

With a bike that sat that long, I would strip it down to the intake ports, check everything and rebuild.

Check the o-rings on the intake boots (if they look like piston rings, they're shot). Check the intake boots for cracks and tears. Ensure the carbs are mounted and adjusted properly. With the airbox off, you can synch the carbs - just make them all the same flow, the part about the outside cylinders being higher only applies with the airbox in place. I found synching without the airbox a lot easier for hand room, though you have to have some faith because the bike won't rev up like that.

I think if you check that part of the system for leaks, and be sure to synch the carbs (the shop might have done it, but they won't do it with the love you guys will), that bike will run right.

[Kabonkie]

I'd agree. Mine sat for just a year and I had to pull the carbs apart and clean all the junk gas out of them. Even found it in the enrichment area for where the choke connected.

With a bike that has sat that long, I'd bet the carbs are gummed and why you have to have the choke on to get it to run. And if the jets are gummed then that would also explain why it won't rev.

Of course you need to sync the carbs when you finish cleaning them.

And while they are off, good time to inspect closely all the boots.

[Anonymous]

Thanks for the advice. The more I think about it the trouble has to be with the carbs. I'll do a recleaning and reinspection, check the seal and boots at the same time. I'm sure they will have to be replaced. I just wish it wasn't -10C out. My fingers are going to get cold!

Cheers