Getting close to giving up, bike wont run on all 4 cylinders

[Cmarino]

Hi everyone. Mysterious, unsolvable problem with my 82 650gl that no shop around me is bothered to look at

New parts: Air filter, plugs, coil pack, and carbs were just cleaned with new air flow screws
All intake boots are good and every air connection is tight. Petcock works fine, gas instantly pours out full stream when on prime and actuates when on vacuum.

What works: Good compression, good spark in all four, gas is reaching the carbs, carbs are cleaned and gas is getting to engine.

The issue: No matter what I do, this bike will not run on all 4 cylinders. It has no problem starting up and running as long as it can, but it will only run on 2-3. When it's like this, it will only idle at 4000 rpm, is slowly responsive to gas but rpms will increase all the way, and nothing will lower the idle. The other option, when moving around plug boots, is it will run on 2-3-4. When it does this, it idles fine at 1500, but dies if you give it any throttle. Before doing the carb rebuild, it would run on 1-2-4, so I know cylinder 1 is fine.

What else can I check? Running out of options here. Maybe Ill get the carbs professionally rebuilt? They weren't that dirty when I cleaned them, I don't think thats an issue.

 

[chuck hahn]

Bench sync them and vacuum gauge vsync them once running. do valve adjustments. check float hts per the service manual specs

 

[chuck hahn]

STORE THIS PLACE. service manuals and carb turtorials on right margin

http://members.dslextreme.com/users/bikecliff/

 

[alke46]

My only concern is how well the carbs were cleaned and by who.
They MUST be completely torn apart and either soaked overnight in Berrymans carb dip or ultra sonic cleaned. No shortcuts permitted.
As Chuck says, follow up with a good bench sync then vacuum sync.

 

[alke46]

I also see no mention of the last time you checked valve clearance. Very important.

 

[chuck hahn]

I do rebuilds. Contact me via a PM should you need me.

 

[Cmarino]

How could valve clearance cause this issue though. I know the all cylinders are capable of running since they have before, but besides that all compression is good.

 

[Cmarino]

Personally cleaned, they weren't soaked just sprayed. But again from my perspective they really weren't very dirty, which is why I am hesitant to putting money into getting them professionally done, but I'll look into it

 

[chuck hahn]

ok.....so youre problem is most likely still dirty tiny passages in the carb bodies or way out of sync. i would try doing a very very careful bench sync first. set the top mixture screws at 1 1/2 out from gently seated. Be sure the tips arent broke off inside the holes too.

 

[grcamna2]

ok.....so youre problem is most likely still dirty tiny passages in the carb bodies or way out of sync. i would try doing a very very careful bench sync first. set the top mixture screws at 1 1/2 out from gently seated. Be sure the tips arent broke off inside the holes too.

This is good advice,thanks Chuck :smile:

 

[chuck hahn]

They werent soaked just sprayed. Carb spray will shoot through real easy but NOT remove scale and super hardened gas shellac. all you did was fool yourself and now they need CLEANED properly. Dont feel bad...call it another lesson learned.

 

[Nessism]

You might want to check the carb rebuild tutorial and Newbie Mistakes thread linked in my signature. Rebuilding the carbs properly is easy, it just takes some time.

 

[xkaes]

Rebuilding the carbs properly is easy, it just takes some time.

And as I've found out, careful attention to details!

 

[timebombprod]

I learned the same lesson they need to be rebuilt and dipped, not just sprayed, but you can use the spray to make sure all the carbs passages work properly, and the sync is very important aswell.