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CT/AT Straight cut clutch gears.

  • Devin
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CT/AT Straight cut clutch gears. was created by Devin

I'm in the planning stages of reproducing straight cut gears for the AT/CT models. The more I make the cheaper I'll be able to sell them. If you have an interest in obtaining a set, let me know, as I’m trying to determine how many to make. These gears are a bit noisier then the stock helical cut gears, and primarily used by racers looking to gain an edge on their competition.

I'm not taking pre-orders as of yet, as I also plan to have them both heat and cryogenically treated for added strength and hardness. Stronger and harder means they'll be more wear resistant then the stock Yamaha gears, and should hold up much better in competition. They'll also need to be tested on a bike before going to market.

The benefit of such gears will be reduced frictional losses which equates to more usable power being transferred to your rear wheel.


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Last edit: 25 Apr 2020 15:54 by Devin.
25 Apr 2020 12:38 #1

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Replied by Pillsbury on topic CT/AT Straight cut clutch gears.

This is great news!! Wish they worked on a DT
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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25 Apr 2020 13:29 #2

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Replied by Devin on topic CT/AT Straight cut clutch gears.


Thank you. I am currently working on a project that will need these CT/AT gears ( The Mean Green Machine ), so I’m starting with these first. Eventually I would like to make DT/RT sets.
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Last edit: 25 Apr 2020 15:31 by Devin.
25 Apr 2020 15:24 #3

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Replied by Youngdrakeo on topic CT/AT Straight cut clutch gears.

What ratios will you be looking at?
Running a oil pump will be out of the question too.
73 CT3 modified, 74 AG175 MX, 79 YB100 x2 , 79 GT 80 ,2015 ducati scrambler ,honda CT70
25 Apr 2020 16:16 #4

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Replied by Devin on topic CT/AT Straight cut clutch gears.


the stock versus straight-cut ratio is slightly different. Stock is 19 / 74 teeth = 3.894 ratio. These will be 18 / 69 = 3.833. Not much different, but favors racers looking to add a few extra mph at top speed

Yes, that’s true. I will look into making a straight cut gear for the oil pump once I complete this project. I like the option of having an oil pump instead of premix. For now these will only work with pre-mix.
Last edit: 27 Jun 2020 13:54 by Enduronut.
25 Apr 2020 16:40 #5

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Replied by Wheels on topic CT/AT Straight cut clutch gears.

I’m interested in at least one set.
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25 Apr 2020 18:06 #6

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Replied by johninga on topic CT/AT Straight cut clutch gears.

What is the benefit of straight cut gears?
25 Apr 2020 20:41 #7

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Replied by Devin on topic CT/AT Straight cut clutch gears.

The benefit of such gears will be reduced frictional losses which equates to more usable power being transferred to your rear wheel.

For example: you might make 20 horse power at the crank, but thru friction lose it could be down to 17 horsepower at the rear wheel, when using stock helical gears. These help with less frictional power loss, so you may have 18 horsepower instead of 17 at the rear wheel.
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Last edit: 04 Apr 2022 23:21 by Enduronut.
25 Apr 2020 20:43 #8

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Replied by JayB on topic CT/AT Straight cut clutch gears.


Reduced side loading on the crankshaft and clutch. The helical gears push in and out on each shaft depending if you are accelerating or decelerating.
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26 Apr 2020 06:30 #9

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Replied by MarkT on topic CT/AT Straight cut clutch gears.

I'm interested.
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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26 Apr 2020 06:55 #10

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