Rough idle on 1980 GL1100

[gcorbitt]

I just bought a GL1100 that has been sitting for a few years. The carbs were just rebuilt by a qualified mechanic, but the idle is very rough and noisy below 1500RPM. At 2000+RPM the motor is strong and sounds normal.
I have been told that it is usually the idle jets that need attention, but my mechanic assures me that he cleaned the jets when he rebuilt it. Also, When a jump box is hooked to the battery, the noise and the idle smooth out.
Where should I start in diagnosing this issue? Do I remove the carbs and clean the idle jets again or are there other issues (like ignition) that would cause such performance?

 

[plskthompson1]

Sounds like an electrical issue if it idles fine with the jump box. I would start by checking the charging system output.

 

[Hoosier Daddy]

Sounds like an electrical issue if it idles fine with the jump box. I would start by checking the charging system output.

I agree... if the charging system output is ok, check voltage supply to the coils.

 

[AApple]

Does it start without a jump box? Definitely sounds like either a charging system problem, or some corrosion in some of the connectors. Check the voltage at the batt with it running first...that will give you a starting point.

Welcome to the CGW forums, btw!! :clapping: :clapping: :clapping:

 

[dan filipi]

Well I'm thinkin.........when the jumpbox is connected, load is taken off the stator hence less load on the engine which is masking a carb problem. I could be wrong of course, certainly wouldnt be the first time, but have the carbs been synced?

 

[gcorbitt]

Carbs have not been synced yet

 

[dan filipi]

Carbs have not been synced yet

Do that next.
These engines will sound like they're going to break apart when out of sync.

 

[BigAndrew]

:salute: Welcome to the site...

When trying to run my bike without a battery by push starting it, It ran like crap... Wouldnt rev over about 3500 rpms and would choke out when trying to rev it as if it has a serious carb problem