So I tore apart the motor this weekend. Found that one of the crankcase bearings was starting to go, and clicked while spinning. Glad I looked into it! Motor has about 3 hours of run time on it, so I was a little surprised, but it has been run HARD.

So my goal is to get more RPM’s out of it. I have gotten to 16k so far. I will be reporting back what I max out at now. Here is what I did to it.

So I installed new Ceramic crankcase bearings.

I am now going to test out the theory of reducing the piston weight for more RPM’s. I bought a Gizmo full mod Zenoah piston. Also found a trick piece, a titanium wrist pin. This has reduced the weight by about 9 grams. I have pictures of the weight below.

Titanium Wrist pin

Stock 290 wrist pin

Modded piston

Stock Piston

Also installed a modded 1048 carb, and matched the v-stack to the larger venturi. I had to swap out the throttle shaft arm form the 990 to this carb so I can use the swivel that I like.