Author Topic: DT 200R Piston question  (Read 672 times)

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Offline vmxrider

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DT 200R Piston question
« on: July 01, 2020, 02:00:28 PM »
I'm helping a friend rebuild a 1990 Yamaha DT 200R.
It has a case reed engine, so the stock piston has no windows in the intake side.
The replacement aftermarket piston he has lists as being suitable for a 200 blaster (air cooled) and a DT 200R (water cooled). This piston has intake windows.
Want to make sure it will work before going down the path of rebore etc.
Any advice or suggestions?
 

Offline sleepy

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Re: DT 200R Piston question
« Reply #1 on: July 03, 2020, 10:09:25 AM »
Can't say that I've seen inside a DT200R but if it is case reed then the intake timing is controlled by the reed so a piston cutaway shouldn't cause an issue. I did look in the Wossner and Wiseco books and the DT200R piston has a different part-no. to the Blaster but the diameter and compression heights are the same. I also looked at Pro-x and they list the same piston for both, it has the ported piston.

Offline vmxrider

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Re: DT 200R Piston question
« Reply #2 on: July 04, 2020, 04:29:15 PM »
Thanks Sleepy, as you say the intake timing is controlled by the reed so windows in the piston shouldn't be an issue.
The piston he has already bought is a Pro-x so will bore it suit and see what happens.
Worst case is will have to buy the another piston and top end gaskets.

Offline vmxrider

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Re: DT 200R Piston question
« Reply #3 on: October 01, 2020, 02:43:21 PM »
The engine is back together with the blaster piston and all works.  :)

Offline James P

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Re: DT 200R Piston question
« Reply #4 on: October 03, 2020, 02:43:20 PM »
The engine is back together with the blaster piston and all works.  :)

Good to know its working OK. For background info; The DT200R had cylinder reed intake from 1984 to 1987, then crankcase reed intake from 1988 onwards.

Regards,
James