our 04 or 05 150cc with my 210 lbs maxes out @ 33 mph and that's all she has, it's the full auto. so my question is this, what can i do to increase the top end ?. would a taller rear tire or maybe changing the sprocket to lower the rpm's..mike

 

What size rear tires do you have on it now?

My Jet 150 only does about 30 mph with 20x9.00-8's on the back. Stock it came with 19x9.5x8 tires. I put on some some general purpose knobby tires to give it traction in the snow. It works really good with them on. The stock ones were smaller, lower profile, great for spinnin donuts but not great for trail riding in the winter on snowy conditons.

Either bigger tires or change your sprocket Ratio's. The more top end speed - the less bottom end torque you going to have.

 

rears are the 18 - 9.50 x 8. i would rather be able to have it run out at 40 than being able to spin the tires on gravel and it does that real good it sure has the low end but like i said she's maxed out after 100 feet. i'd like to know how or what others have done to run in the mid 40's? , or are they just going by the dealers adds. when we bought this one i'm sure it said top speed of 45 mph and when driving it, it does feel like it's realy hauling until you clock the true mph.

 

My 04 Yamoto 150 and 06 Jetmoto 150 stock go 32 mph... The Yamoto 150 now is good for 37-38 mph thanks to a aftermarket CDI Box. It also now has a Jetmoto 150 carb with larger pilot and main jets.

As for the claimed top speeds..they are exactly that...claimed