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Straight cut drive gears

10 Dec 2019 20:26
Mark350
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Straight cut drive gears #1
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.

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10 Dec 2019 20:56 10 Dec 2019 20:59 by RT325.
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Straight cut drive gears #2
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

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10 Dec 2019 21:42
MarkT
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Straight cut drive gears #3
Enduronut or DEET might have a set... might not be for sale but it couldn't hurt to PM them and ask.

1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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11 Dec 2019 07:50
mdscott
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Straight cut drive gears #4
I remember my old Huskys had straight cut primary gears, I loved the whine they would make.

Thanks Mark
Roseville, Ca.

'76 Bultaco 143 Frontera
'06 GL1800
'01 KDX220
'68 YG5T 80 Trailmaster
74 DT360
75 Norton
73 CB500K
63 C200
87 PW50
64 McClane Edger

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11 Dec 2019 12:29 16 Jan 2020 07:47 by Pillsbury. Reason: info was wrong
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Straight cut drive gears #5
What'cha building..........any pics?

1970 DT1-C Grand Prix race bike
1970 DT1-C Street tracker
1968 Honda CL90
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1947 Mustang
1974 Suzuki TC185

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11 Dec 2019 13:11 11 Dec 2019 13:12 by RT325.
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Straight cut drive gears #6

Pillsbury wrote: The clutch & primary gear from a 1989-92 Yamaha YZ250A will fit. Try to buy the whole clutch assembly. Look at the pictures, some of the clutch baskets are so bad the clutch would be rough. There are some nice sets but the good ones cost more & go quick. The engine gear is easy to get so if you don't get a matched set buy a few GOOD used gears (new is available also) and use the one that matches the best.
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.

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11 Dec 2019 15:44 16 Jan 2020 07:49 by Pillsbury. Reason: still the same dumbass :)
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Straight cut drive gears #7
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RT325 wrote:

Pillsbury wrote: The clutch & primary gear from a 1989-92 Yamaha YZ250A will fit. Try to buy the whole clutch assembly. Look at the pictures, some of the clutch baskets are so bad the clutch would be rough. There are some nice sets but the good ones cost more & go quick. The engine gear is easy to get so if you don't get a matched set buy a few GOOD used gears (new is available also) and use the one that matches the best.
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 :Ugh

1970 DT1-C Grand Prix race bike
1970 DT1-C Street tracker
1968 Honda CL90
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1947 Mustang
1974 Suzuki TC185

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11 Dec 2019 18:50
Mark350
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Straight cut drive gears #8
Thanks for all the replies. Working on the RT-1B shown.

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11 Dec 2019 18:52
RT325
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Straight cut drive gears #9
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.

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12 Dec 2019 10:36 12 Dec 2019 10:42 by Pillsbury.
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Straight cut drive gears #10

RT325 wrote: 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 :)

1970 DT1-C Grand Prix race bike
1970 DT1-C Street tracker
1968 Honda CL90
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1947 Mustang
1974 Suzuki TC185
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