bandit 600 idle surge

[snapperslappe...]

my bandit seems to have a niggling problem, upon idle, the revs seem to surge upto 1900 and drop off again down to 1000 intermittently. ( giving wobbly rev counter syndrome)

i noticed the plug on cylinder no.1 is constantly dry sooting no matter what type of riding is employed ( low revs through idle jets/ half jets or high revs through the main jet), so i replaced the air filter, overhauled the carbs, checked all fittings and rubbers ect and changed the plug set. The compression ratio is spot on and the carbs are balanced. Oh, and valve clearences have been checked out and the coils meet the resitance tolerances ect...

when i clean up the plug, the problem stops untill the plug soots again....

any ideas?

cheers

[bish777]

You could have an oil leak from the cam cover in the spark plug tunnel, this will work its way down the threads of the plug causing it to foul.

Leaky float valve or valve seat gasket could cause rich running which leads to the plug fouling. This requires a new outer oring for the float valve seat, no amount of cleaning or fiddling will fix this. Its ertainly possible that it could only be leaking on the one carb.
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GSXR1100J

[snapperslappe...]

i had noticed that the spark plug chamber was abit grimey but thought nothing of it....... cheers bud, this one's been winding me up for ages!!!

would that account for the idle surge also?

[bish777]

My last GSXR1100 had a leaky spark plug tunnel on cylinder 1 also (its a related motor). Fixed it by lifting the cam cover and applying a little instant gasket to the spark plug tunnel gasket.

As for the surge, you may have a problem with the choke mechanism?

Other than that look for seized throttle linkages on the carbs individually and then inlet leaks at your carb to engine rubbers.
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GSXR1100J