CN250 performance tweeks for Roketa GK-13

[Patrick]

I have a Roketa GK-13 with a CN250. The engine runs great but the gasket on the crankcase directly under the cylinder is leaking bad. I have the engine out and am waiting on gaskets and seals to show up. Everything is stock currently but I have ordered Dr Pulley 19g sliders and a yellow torque spring for the clutch, along with a Uni filter and main and pilot jets.

Anyway, I was wondering if there are any easy performance tricks I can do while it is apart? Porting the head, is it worthwhile on these? Milling the head to raise compression (I have a machine shop at home), or is that a no-no with the chain driven over head cam? Not looking for performance cam at this point do to cost. I also have a 400cc yamabuggy for going fast, but would like the Roketa to be a little more fun. Mainly flat land, open trails.

Thanks,
Patrick

[SYCARMS]

Milling the head will increase the compression but no more than .025. Porting the head will make huge gains if done correctly but the key here is correctly. Knowing where to remove material and how much is the key. We do porting $150.00 on your head plus any parts if needed like valves, springs ect.

[Patrick]

Cool, thanks for the information. I will probably just clean up the bowls a little bit and mill the head the .025. After buying the Yamabuggy I have to keep the cost down on the Roketa mods.

Thanks,
Patrick