X-Pro 150cc // Vader 150 // Lifan 150

ProDigit · 04-24-2024, 09:46 PM

Bike ran great cold, but was stuttering when warmed up.
Turns out it was running too rich.
Especially ~5-25% of the throttle.

I can either take the side panels off again, and spend a day trying to adjust the carburetor, or adjust the needle height again; or leave it running rich (bogging), and just replace the exhaust with a free flow one, and hope the rich fuel mixture will be more stoic.

I did do a test with the AF screw to 1 1/2 turn, lowered my top speed to 55mph, or turn it to the off position, have a louder exhaust, but top speed went back up to ~60MPH (GPS).

The pilot jet always was rich.
The jet needle is raised by ~3mm causing an excessive rich condition at ~5-25% of the throttle.
25-75% of the throttle runs fine, nothing unusual noticed. May run rich, or lean, no idea. 75-100% of the throttle seems to have lost speed when running richer, which means top end is now also rich.

I always presumed it would be running lean, because that's what my previous bikes from China always did; but I was wrong.

A two piece exhaust pipe from eBay has arrived, together with the cheapest muffler on Amazon, which I will modify by pushing a baffle in it for testing.

More updates this weekend hopefully.

04-24-2024, 09:46 PM	#15
ProDigit Join Date: Aug 2013 Posts: 86	Bike ran great cold, but was stuttering when warmed up. Turns out it was running too rich. Especially ~5-25% of the throttle. I can either take the side panels off again, and spend a day trying to adjust the carburetor, or adjust the needle height again; or leave it running rich (bogging), and just replace the exhaust with a free flow one, and hope the rich fuel mixture will be more stoic. I did do a test with the AF screw to 1 1/2 turn, lowered my top speed to 55mph, or turn it to the off position, have a louder exhaust, but top speed went back up to ~60MPH (GPS). The pilot jet always was rich. The jet needle is raised by ~3mm causing an excessive rich condition at ~5-25% of the throttle. 25-75% of the throttle runs fine, nothing unusual noticed. May run rich, or lean, no idea. 75-100% of the throttle seems to have lost speed when running richer, which means top end is now also rich. I always presumed it would be running lean, because that's what my previous bikes from China always did; but I was wrong. A two piece exhaust pipe from eBay has arrived, together with the cheapest muffler on Amazon, which I will modify by pushing a baffle in it for testing. More updates this weekend hopefully. __________________
	0