Saturday, March 31, 2012

Electrical issue.

We found after all Electrical diagnosis that needs new coil.

This stator coil cost too much and back order "in Japan". We decided to replace all this old Electrical wires to latest model wire system. That wasn't cost difference much and faster we thought.

Then we found it has three kinds stator coil exit. And that mean three kind of crankcase cover and fly wheels.

Early model coil.

2nd & 3rd generation coil and cover. You can see these two has different mount wholes.

Three generation of Fly wheels.
 Left is oldest, right is latest. 

This is final shape before piece put back to body. 

TW was came out 1987. This one is '89. Yamaha changed only these Electrical system. Now, we can tell this motor is same as latest model!

All TW wire diagrams. Another fun time.

All wire harness switched newer. C.D.I  unit also new.

We doesn't change control switches so, many wire and coupler connection needs change like pictures. We will change control switch too if we have next chance. That saves lot's of time. 

Put back with new screw bolts.

What we changed: wire harness(used. came with relays & regulator), CDI, crankcase cover(used) and stator coil for after 2001~ model.

Friday, March 16, 2012

Carious tooth.

Keep split parts.

Simple is best.

74mm piston required crankcase bored out. We split crankcase and found these worn out gears. It just looks like carious tooth. 

Transmission gear

We know it is still work but decide to replace all gears (and bearings). More time and more cost, It was not expected but safety first. We don't want to see any mechanical trouble on the road, oval track or any other extreme place. 

These bolts were off from this motor. 

Right size tools and right maintenance would not make like these bolts. We service for you if you don't have time or tools.  (Contact information is on )

Bearing fitting

We waiting all gears and bearings parts will arrive.

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.