im new to this [2]

Go with Dax. That would be your best bet . With Dax., you just can't go wrong

Zoom is best bang for the buck when taking shipping into consideration with Dax not far behind. Others are not even in the running here.

Raw engines are good!

i got 4300kms out of my zoombicycle kit, they have great support, they honor the warranty, and they gave me free parts even after 3000kms of use!! i would buy from them again,

the clutch on the engine went and i just never got around to getting new clutch pads so i sold it,

I have done 2 builds with the Zoom slant 80 kit. Both were strong runners. I just rebuilt the top end on one cause I lost one of the ring groove pins and gouged up the cylinder. I bought a piston and jug from Dax thinking there'd be the same. They aren't.. The Dax motors use a bigger piston wrist pin and a slightly (about 1/16") shorter jug. Bore is the same. My next motor will be a Dax. Bigger bearings are better. Shorter stroke is better. Your giving up the slanthead so you may want to order a head. The slandheads have way better combustion chambers. You gain a cool chrome tank. The top connecting rod bearing in the Dax is alot bigger and the rod has 3 oil holes. That will extend the life of the motor alot. Nothing against Zoom they have treated me right. The Dax motor internals are just better.