Thanks for the pictures, I need one from the rear with a close up on the tension bolt?

I am put the original engine back in due to the lack or torque and the super loud noise. I have all the wiring harness parts and am putting that back together. The 150cc seem to be easily modified and parts are easy to get. The other question I have is the clutch housing was blued and the belt was worn would those cause the lack of power and torque with the 150 engine.

How much riding time do you have on your buggy usually any metal part being blue is gause by excessive heat maybe your clutch pads are shot.

The pads appear to be new and drum was glazed
I roughed the drum and put on a new belt

I would check the rollers and make sure the vari slides smoothly.What size sprocket you have ? Theres alot you can do with a 150 just dont know what you have to start with

here is a couple pictures.
yep i agree with some cvt mods and get rid of that 31tooth axle sprocket to a 39 tooth and you will see a different buggy.
i don't know if you know this but if you have the 2 bolt valve cover style head, there are no 155cc kits cams and things like that,that will fit this engine.the stud spacing is wider for cylinder and head.also my self i have not found a performance exhaust that will fit without modding the the mod,just to much money for me to be bending or cutting on.
stock exhaust does good drilled out still get a good flow and good bottom end.
if i can get traction and keep the front end on the ground i can climb pretty good