Author Topic: Can a DT1MX race in Pre 70 classic motocross?  (Read 1344 times)

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Offline sleepy

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Re: Can a DT1MX race in Pre 70 classic motocross?
« Reply #15 on: November 02, 2018, 01:45:30 PM »
Yes its a pity there is no Official MA site/contact  to get a definitive resolution over eligibility concerns .

It is a pity but in this case they would ask 2 questions. Is it a DT1 and is it piston port and with yes to both it is in.
Doesn't maker weather it's a DT1 or DT1B or DT1S or DT1C or DT1E or DT1MX it's still a DT1.

Offline John Orchard

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Re: Can a DT1MX race in Pre 70 classic motocross?
« Reply #16 on: November 02, 2018, 01:49:08 PM »


1971 DT1E
Mandarin Orange
DT1F-00101 to 03492   > (Close ratio transmission)


What's the story with this one?
Johnny O - Tahition_Red factory rider.

Offline Iain Cameron

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Re: Can a DT1MX race in Pre 70 classic motocross?
« Reply #17 on: November 02, 2018, 07:24:41 PM »
It was for Farmers not what comes to mind . It is a nice box of gears though not many around . Congrats on the buy from Terry , John. I will send you a PM . 
Yamaha tragic ; dt1, rt1, dt2, rt2, dt2mx , rt2mx , mx250, mx360,sc500, 74dt125, yzx125, yzc250, yzc400, yzd250, yzd400, yzh250, yzh80 , dt100 , xr75 ko xr80 03 , it175 82 . Not a member of any club

Offline sleepy

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Re: Can a DT1MX race in Pre 70 classic motocross?
« Reply #18 on: November 03, 2018, 11:21:40 AM »
It was for Farmers not what comes to mind . It is a nice box of gears though not many around . Congrats on the buy from Terry , John. I will send you a PM .

Didn't the early 68 models have the close ratio box as well. The parts book shows the from no 38000 there was a whole new set of ratios.

Offline crossedup2

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Re: Can a DT1MX race in Pre 70 classic motocross?
« Reply #19 on: November 04, 2018, 08:32:09 AM »
The best thing about any of the DT1-DT3 and RT1 -RT3 (MX as well) is that all the parts are pretty much available and most are interchangeable (even with later models). However con rods and pistons are different on the DT1.

In the AT1M, AT1MX, DT1MX and other "M or MX" variants they had different ratios in the gearbox, carby, pipe, small changes to cylinder and head. There are other minor changes also which you can find.

I run an RT3 bottom end in an RT3 frame, piston port cylinder, MX250A gear set (fits straight in), YZ250 clutch pack (extra plate), and a YZ400E stator and CDI. It's all pre 70 legal.

If you want the genuine DT1MX you have to chase the case numbers as Ian said. The GYT stuff is like rocking horse poo. But worth looking for just good luck finding it!

Peter B
Anything Yamaha. AT1, CT1 (X3), RT1, DT3 (x3), YZ125X,  YZ250E, YZ400D, IT175E, IT250H, IT490K . Always looking for Pre 78 Yamaha stuff....