My m20 runs well but it's developed a surging at near max revs. The motor is ticking over great, but it's like something is slowly the bikes momentum. hard to explain, it's like the brakes are catching in one spot. I was thinking that I may need to change the engine sprocket from 19 to a 20 tooth. Has anyone else had this problem?
If it's OK on a rising throttle but only gives the symptoms when it's wide open, that suggests richness on the mainjet. It could be float level or fuel type related.
It's certainly worth checking the fuel level and float needle sealing. I'd have look with the float chamber top off. When you're giving it a big handful, an unsophisticated engine and carb setup like we have will cope with a bit of over-fuelling within reason.
Many times it can be rectified by adjusting the timing, but first-
The points gap, and oiling the points pushrod.
(going from points-cam to top point) and generally going over the
Inanition system: Hi-tension cable, pickup, mag brushes, sparkplug.
Just case that the carb check would not work..
Anyway, the carb should not leak with tap opened, unless using a side/desert stand.
