Saturday, March 3, 2012

Motor work.

We working on yamaha air cooled 200cc motor.




It was a rough shape when we picked up. 




We decided to re-fresh motor for street and off road use. But Koji found this tire fits. Things going much more interest for dirt-track!



but first, bike has no spark. (We'll put on article for Electrical issue later.)




  The plan will going to stroke up and bored out from 196cc to 249cc. Also we make original big valve for this motor. It's sounds going to be like racing quality motor but reasonable cost is the key as this bike. We are plan to this tune will be service through from Furuhashi Racing to all motorcyclist. 


"Big valve motor makes good top end power. I have to see their tail when I race with those bikes. It is good tune up for motor performance side." Koji says. (*big valve is now prohibit on GNC singles class rules.) 




We going to change also High lift camshaft from webcam, valve spring and retainer. SOHC two valve air cooled motor means simple "friendly" motor. 




Stock air cooled rotax motor wasn't powerful enough for street bike but turned best motor for GNC dirt track race. Because it had capacity of durability for tune up. This 200cc motor has little space for that way. It will not for latest racing caliber but looks pretty enjoyable for all level users. Let's get some fun and see how it goes! 




Bore and stroke size will be 74.0mm x 58.0mm This number as same as yamaha XT250. It could order made racing high compression forged piston but we choose OEM yamaha piston this time. We want to use less than race machine maintenance cycle this bike for street and dirt use. Fun ride is another key.  




Stock bore is 67.0mm. It needs bored out with re-sleeve. We are in these process now at LA sleeve




We'll up date all work.

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