Motorcycle Repair: suzuki 125, suzuki 125 intruder, v twin

Question
Suzuki 125 intruder v twin.
Running very sluggish and stalling.
left plug is black when removed whilst right one is ok.
Air filter is clear .
Any ideas?
It has had  previously trouble with the spring in the choke on the carb side which the shop replaced , could this be tha problem again?
it is a 2002 model.
thanks

Answer
Hi Ken,

I suspect the carburetors are varnishing causing the running problem and/or the plugs are being carbon fouled during the starting process.

I would have to inspect the choke and carbs to verify the choke is the problem. I would say yes, the spring could be the problem again. I would look for varnishing around the choke plunger which would cause the plunger to stick or drag. The choke plunger spring would not be strong enough to return the plunger to open positon (choke off). Visit this link to see microfiche parts on line: http://www.motofiches.com/sites/TYRBUW/fiches.asp?bt=17&mk=SUZUKI&cc=125&ml=VL12...

If you are mechanically inclined and want to do the repairs yourself, send me your email address as requested and I will return repair information files. I think your problem is a simple fix for a tech, but the work is time consuming, meaning expensive. :(

Respectfully,
Mark Shively