Aspooner25 wrote: Will this set of straight cut gears require clutch basket modifications?

Possibly. The TZ model’s used straight cut gears and had high performance needle bearing. I might have to modify the sleeve depending on what bearing is used. I will let you know the final outcome, but if modifications are required I would offer that service. These will also have to be riveted back on.

JGersh wrote: I’m interested but would like to keep running the oil pump...

Thanks for the interest. I will be making a straight cut nylon oil pump gear for the set up (eventually). I will have the prototype of the gears done in about 30 days.

Terry good wants a set as well, for his museum. He is opening a museum and will have about 120 works bikes! He will also have tons of memorabilia from Joel Robert, Roger Decoster, Toresten Hallman, Bob Hannah, the late Marty Smith, a reproduction Gary/Don Jones workshop and more. Enduronut and I will be visiting when it opens. Here is a great interview from Joe abate with Terry Good.

Okay. That makes sense. I was just curious about the mounting of the clutch gear. I am very much interested in getting a set or two. I will be getting my engine parts back from the machinist soon and am curious when these might be available for purchase. Thank yall, Austin.

Here is a factory works bike. The 1971 YZ644. At the time it was unbeatable, in its class. The factory did a lot of weight reducing modifications in addition to the straight cut gears.

Aspooner25 wrote: Okay. That makes sense. I was just curious about the mounting of the clutch gear. I am very much interested in getting a set or two. I will be getting my engine parts back from the machinist soon and am curious when these might be available for purchase. Thank yall, Austin.

This project is not going to be rushed, it will be done right with lots of testing and metal treatment. They will be stronger and harder than the factory Yamaha gears. I estimate it will be completed in 2021. I was going to make 30 sets but decided to make 50.

Completely understandable. In the mean time I'll install the stock gear set. I and everyone else here is grateful that you are doing this and keeping these ol' bikes on and off the road.

Devin wrote: Here is a factory works bike. The 1971 YZ644. At the time it was unbeatable, in its class. The factory did a lot of weight reducing modifications in addition to the straight cut gears.

Is the flywheel off in this picture, or is there no flywheel?

It had no flywheel, it was a button points magneto. Very fast acceleration!!.

Wow the info on the works bike is very cool, Ill be interested in a gear set.

Mako posted this a few years back- Yamaha Factory AT1 Special (YZ644) 1971

yamaha-enduros.com/index.php/forum/gener...1-special-yz644-1971

Continued progress....The prototype gears are completed. Next I will be designing the straight cut gear for the oil pump.