by James Addiction » Wed Mar 12, 2014 6:11 pm
I posted this over at Thumpertalk:
"My wife's bike is acting strangely. It starts easily, it warms up smoothly, it idles pleasantly, and it rides ok... except that it doesn't ride ok. If the throttle is twisted past about 1/4 of its full travel the engine starts to chug. It's like hitting a rev limiter, but the RPMs don't matter. If the throttle is backed off until the chug is gone, the bike will accelerate smoothly if slowly. I got it into 4th gear just to see if I could.
So that's the thing. It works completely normally unless the throttle is twisted too far.
I have checked the entire fuel system to include the petcock, hose, and fully dipped and sprayed the carb.
I have a fresh clean air filter and a shiny new spark plug.
I checked valve clearance and found the exhaust to be a bit wide. I adjusted it to specs but no change to performance.
Fuel is fresh, with a hint of stabilizer in it.
Only thing I don't know how to check is the coil and the ICM. I have a manual and it shows a special add-on device for a multimeter [not available in the US, and a $600 device] to read peak voltage.
I don't know if float level would have anything to do with this problem, but the spark plug looks correct - not too lean or rich.
I'm out of ideas."
I was given the tip to nip off a bit of the spark plug lead and screw the cap back on. I did that but nothing changed.
So, I'm thinking coil. Agree? Disagree?
James Addiction
2008 CRF 250 X
2006 CRF 150 F (Wife's)
2006 GSX 600 F Katana
2005 CBR 600 RR (it's an entirely different kind of flying, all together)