Carbs or electrical problem???

[Anonymous]

Hi all from the UK!!
I,ve got a problem with my 1980 GS850, (pretty much standard
apart from a `Motad` 4 into 1 exhaust).
I took her out for a ride this afternoon, which was the first time in a week due to the crappy weather over here recently. Started and ran fine initially.
After about 2 miles of city driving, pulling away from a set of lights, it seemed to have lost power,(as if running out of fuel) petcock to reserve - no difference. Pull over, idle,s fine and will rev ok.
Underload, it gets to about 2500revs and starts to act up.
Now I,m in a `head scratching ` mood :? as to what to check out?
Help!!!!!!!

[daveo]

I'd start with the fuel filter and petcock, definitely sounds fuel related, most likely not enough

[frosty5011]

I'm with Dave - sounds like fuel starvation. Maybe also check for kinked fuel line. Give the petcock a complete test....if you don't know how to do this, let us know. Good Luck!

[Anonymous]

Hi Guys.. I appreciate your help.
I,ve checked the operation of the petcock, and its working as it should with good fuel flow?????????????

[daveo]

no kinks in the fuel line itself, no rips or kinks in vacuum line from #2 to petcock, carb bowl vent lines open?

[Anonymous]

Check that the timing is advancing properly.

[daveo]

Check that the timing is advancing properly.

Good call Andy, they do seize up

[Anonymous]

Thanks all...
The fuel line /Vacuum pipe seems to check out ok..
I,ll move on to the advance.......(It does seem like the symptoms if your points weren`t adjusted right on on a points equip`d bike) I,ll let you know.

[AOD]

take off the timing cover and rotate the mechanical advancer by hand. it should turn about 1/4 to 1/2 an inch to your...right? if i recall correctly. it may be kind of difficult to reach if you have points, but it sits right behind the points...on the shaft. it'll have some springs and weights attached to it. when you turn it, the weights go outward.

it may be in your best interest to take the points plate off (three screws) OR CDI box, and check the advancer. if its free, put the plate back in position lightly, and put a timing gun on it, set the idle to ~3000, and check the timing on the #1 mark.

if this is all good or it runs the same afterwards...its time to investigate the fuel supply and carbs.

~Adam

[gs650gt]

did You try to running with choke on ? or the fuel petcock in the "prime" pos ?

If the problem then disappears, You probably suffer from fuel starvation...

[Anonymous]

Riding in the rain?

If riding in the rain, or after it sat out in the rain makes it act up check that the spark plug boots are dry.

You may have to dry them on the wire side, and on the plug side. It never hurts to trim back the wires. Not often, but atleast once after the bike has been riden for 20 yrs.

[Anonymous]

Thanks again for your ideas...........
I,ll have time tomorrow to investigate further, I,ll let you know any progress! (he says hopefully!!!!!!)

[Anonymous]

A RESULT!!!!!
Checked the `ATU`, sticking.......Lubed & took it for a blast!!
No problems!
Thanks all!

[AOD]

ATU? the mechanical advancer for the timing?

anyway, glad to hear its working good now.

[Anonymous]

yeah.... For `ATU`(automatic advance unit) read mechanical advance.
Cheers all.