Running very rich '85 NQ50
Posted: Sat Oct 27, 2018 11:50 pm
Need yet more help. I've rebuilt many motorcycles and scooters, and I wouldn't consider myself a novice, but this one has me stumped. My '85 NQ50 was running very well after I initially rebuilt the carburetor. I'd say I rode it around 50 miles or so without a complaint. It would light right up with a momentary touch of the starter. Then my starter pinion started sticking and began making starting a bit rough. It would always start, but now needed a little throttle to get it to light off, likely due to the drag from the sticking pinion. I decided to fix the starter pinion problem...and did...but now I can't get it to start up reliably. It seems to be running very rich...e.g. when I pull the plug after starting attempts, it is wet with fuel. I had done nothing significant, save for the starter pinion fix, that should affect mixture.
So, the syptoms are that I cannot get it started without cracking the throttle...and then it won't idle without some throttle applied. To try to fix the issue I've done the following:
Pulled the carb and recleaned it...Result: looks spotless
Checked the auto bystarter function with a 12v power supply...Result: works as intended.
Pulled the spark plug and checked spark...Result: Fat white sparks.
Adjusted the mixture screw to determine effect...Result: runs better as the mixture screw is backed out, but not nearly enough to fix the problem.
Pulled the air filter to determine effect...Result: no change.
Pulled the petcock vacuum line from the intake to determine effect...Result: substantially better running. Won't start without some throttle, but will idle stably.
My experience with two strokes has generally been battling a lean condition...all indicators here say I'm running rich...
The scooter was running very well prior...not sure what could change to suddenly give me a rich condition?
Any thoughts from the community?
So, the syptoms are that I cannot get it started without cracking the throttle...and then it won't idle without some throttle applied. To try to fix the issue I've done the following:
Pulled the carb and recleaned it...Result: looks spotless
Checked the auto bystarter function with a 12v power supply...Result: works as intended.
Pulled the spark plug and checked spark...Result: Fat white sparks.
Adjusted the mixture screw to determine effect...Result: runs better as the mixture screw is backed out, but not nearly enough to fix the problem.
Pulled the air filter to determine effect...Result: no change.
Pulled the petcock vacuum line from the intake to determine effect...Result: substantially better running. Won't start without some throttle, but will idle stably.
My experience with two strokes has generally been battling a lean condition...all indicators here say I'm running rich...
The scooter was running very well prior...not sure what could change to suddenly give me a rich condition?
Any thoughts from the community?