In 1972 bought a straight cut gear set (crank and clutch basket gear) for a '71 RT-1B. Have never seen one since, but am looking for one. Made a great whining sound. Any help appreciated.

YZA & B 250/360 had them but no chance of finding a set nowdays. I had a set once in some yz250a bits i got given & used them on a 250 piston port motor i built up.
www.partzilla.com/catalog/yamaha/motorcycle/1974/yz250a/clutch

Enduronut or DEET might have a set... might not be for sale but it couldn't hurt to PM them and ask.

I remember my old Huskys had straight cut primary gears, I loved the whine they would make.

What'cha building..........any pics?

Is that 'true' that an "89 primary gear & basket will fit a "71 RT1 or did i miss something somewhere?. YZA i was talking about was "74. Very interesting if correct though.

Some that I race with say yes, but I say no, the spacing between the gears is wrong.. I am still looking for a better gear set than the 1st year close ratio (large tooth) they just don't hold up to sustained high rpm well. The later DT type seem to be all gone or sitting on shelves gathering dust

Thanks for all the replies. Working on the RT-1B shown.

Yes talking the gearbox itself my 69 broke the coarse tooth third gear big wheel on the output shaft & went out through the bottom. That was in "69. In about 1990 my RT2 with RT2MX top end & running the early coarse tooth 250 box did the same thing & made a hell of a mess. I used those gears because i liked the ratio spacing all the way through compared to the fine tooth later trail box.

I did 6 races and some track days, changing the oil after each weekend and wore the gears down to the point it was dropping out of gear. This year I replaced every part in the tranny and started running synthetic oil. No more metal in the pan we'll see how she looks after 2020 race season. I like the ratio also, but those chunky gears scare me at the 7-10,000 rpm I'm running. Hopefully she doesn't blow in a corner. Willow Springs is wide open in 5th down thru corner 8 and that's with 15/34 gearing. There are close ratio small tooth gears out there, I just can't come up with anything. A person I know has a NOS set, but he has loaned it to a gear making place that is going to re produce the entire set for sale to the racing crowd. I don't know how long that will take! BUT, he has my order