Main Jet
 

I'm riding a 2000 E-Ton Beamer 49cc. I upgraded the carb, air intake,CDI box,coil and spark plug. Right now I'm getting 40mph and wondering if up jetting to a 90 main jet would make much of a difference? I believe my jet is a 75.

Any thoughts welcome.

Pappy

Is it de-restricted? Washer out of the variator? No exhaust washer? Is it a model with a rev limiter CDI? It could just be the final drive gearing is low from the factory. I assume its a 2 stroke, as I recall Eton still doing them (2 strokes) in the early 2000's. Sometimes you need a exhaust that allows the motor to reach its peak power/power band. I hear, but have never confirmed, that Yamaha bug-eye 2 stroke parts work on that motor. I no longer have any tuning exhaust laying around for a horizontal motor or I would offer to see if it fits. And dont jump from a 75 to a 90 main jet if you decide to try it. Buy a complete range main jet kit and climb up till it starts to bog, then go down a jet #. Then, if needed, fine tune it thru the needle slide. Hope this helps!

I would raise it to the next jet size and take a plug reading following a top speed run. If the plug shows you are too lean, go to the next jet size and repeat.
-There is no mathematical formula for jetting. It's all trial & error.

Couldn't agree more. I've seen the same exact engines sitting side by side like 2 different jets to run right. You can use what people with similar mods have done to get a starting point but at the end of the day it has to be tuned to what it wants.