Not firing on all cylinders

[ddaniels]

Well, I decided to try my hand at sync'ing the carbs. Got it all hooked up and started the bike. Then I thought, "Maybe I'd better make sure it's firing on all cylinders." Exhaust pipes 1 and 3 got really hot, but 2 only got mildly warm, while 4 didn't get hot at all. Hmmmmm. I wonder if that's the two pilot jets I boogered up, and decided to leave in hoping the dip got them clean, I thought. So, I took the carbs back off and the only two cylinders that were firing correctly are the ones I boogered up and left in. :-s

So, I guess I'll try cleaning out those two carbs again. I'm getting plenty of spark. I could also do a compression check too I guess. While I had the carbs back off, I took off the intake boots to replace the o-rings. The new ones I bought don't seem to fit correctly. I have to stretch them over and into the grooves. But, of course they won't stay in the grooves for me while trying to put the boot back on. Is it supposed to be this way? I doubt it.

Any other ideas about it not firing on those two cylinders. Runs fairly good for only 2 cylinders though. Not good enough though. Any advice is greatly appreciated!

 

[almarconi]

Any other ideas about it not firing on those two cylinders.

My guess would be the carbs with the stuck jets. No luck removing them?

 

[Guest]

The orings should pop straight in. You must have the wrong ones.

Was the bike on choke when you checked the heat on the pipes? If the pipes stay cold on choke AND off choke, you probably have other problems.

 

[tkent02]

Damn, Bruce, that's good.
Learn something new every day.

 

[TheCafeKid]

I just had this problem myself on a carb cleaning.. Ive done a bakers dozen or more cleanings, and never had a problem, but these had sat for some time.. Thought id done a good job, dipped, washed out, sprayed out, and air blown through em. But, I didnt get the bowl ports for the choke and pilot pickup..Tore em down again and found some gunk there, and magicly the bike fired on all four..go figure.

 

[ddaniels]

My guess would be the carbs with the stuck jets. No luck removing them?

No, the ones I couldn't get out are the ones that are firing.

 

[ddaniels]

The orings should pop straight in. You must have the wrong ones.
That's what I figured. I ordered 40mm like the website said I should have. Is that correct? My bike is an '81 1000G.

Was the bike on choke when you checked the heat on the pipes? If the pipes stay cold on choke AND off choke, you probably have other problems.

The bike was not on choke.

 

[ddaniels]

I just had this problem myself on a carb cleaning.. Ive done a bakers dozen or more cleanings, and never had a problem, but these had sat for some time.. Thought id done a good job, dipped, washed out, sprayed out, and air blown through em. But, I didnt get the bowl ports for the choke and pilot pickup..Tore em down again and found some gunk there, and magicly the bike fired on all four..go figure.

Thanks, I'll have to check those.

 

[Guest]

The bike was not on choke.

Then run it on choke and see if the pipes all get hot. That will confirm that the problem is with the pilot circuit.

What year/model?

 

[ddaniels]

'81 GS1000G

I've already pulled the carbs back off, so after I go through those two carbs again and make sure I've gotten all the crap out, I'll give it a try. Thanks.

 

[ddaniels]

By the way, is there any way to make the choke stay up. When I pull it up and let go of it, it just falls back down. So, I have to zip-tie the clutch lever depressed so I can hold the dang choke cable up. A bit of a pain to say the least.

 

[ddaniels]

I just had this problem myself on a carb cleaning.. Ive done a bakers dozen or more cleanings, and never had a problem, but these had sat for some time.. Thought id done a good job, dipped, washed out, sprayed out, and air blown through em. But, I didnt get the bowl ports for the choke and pilot pickup..Tore em down again and found some gunk there, and magicly the bike fired on all four..go figure.

When I spray carb cleaner in the can down in the choke pickup hole in the bowl, shouldn't it spray out the hole down in the bottom of the bowl? If so, then this would be my problem because I just tried it on one of the ones not working, and it would not spray through.

 

[Guest]

When I spray carb cleaner in the can down in the choke pickup hole in the bowl, shouldn't it spray out the hole down in the bottom of the bowl? If so, then this would be my problem because I just tried it on one of the ones not working, and it would not spray through.

Yes, it should. I use the wire from a bread twist-tie to clean those tubes...and compressed air.

 

[ddaniels]

Thanks. So, this would cause it not to fire on that cylinder?

 

[Guest]

Thanks. So, this would cause it not to fire on that cylinder?

It could be your problem. I still don't know what carbs you have (VM or CV). I had a problem with my VM carbs whereas one of the cylinders would remain cold while on choke. Once off choke the pipe would get hot after it spluttered and sputtered a bit. I found the choke tube plugged up like you have. I could be wrong, but I didn't think that tube was used for the pilot circuit, at least not on the older VM carbs. I thought that tube went directly up into the carb body and mixed with the air for the choke.

 

[ddaniels]

I have CV carbs. I checked and both the carbs for the two cylinders that were not firing had those tubes plugged up. I've gotten them unplugged now. Tomorrow, I'll double check the other two as well. Thanks for the help...everybody....again.

 

[ddaniels]

And I also made sure the pilots for those two carbs were clear...and they were.