Thanks to Mr H. a fine member here donating a CT1 piston for measuring research; I may be close to finding a match for my Honda MR175 project. The Yamaha piston is 6.6 mm shorter but everything else is close. A question for you two stroke experts: how much does 6.6 mm shorter on the piston shirt effect timing etc? thanks

Something to check is that at TDC the skirt on the CT piston is long enough to cover the exhaust port.

If it's not, the crankcase will be open to the exhaust port at TDC which is not a good thing.

I will look for the DT200 piston again tonight... probably will be late

thanks going to do that now.

yeah exhaust port is covered by at least 10mm at tdc.

WEll if the intake skirt is 6.6mm shorter it wont idle and bottom end will be non existant but will scream on top end . Unless it is a reed valve engine , which it is not .

Rich

Those honda MR175 pistons are near impossible to find. Maybe a screamer is better than not riding it . any tricks to make it idle?

The intake port timing might be very mild to start with. A lot of the Enduro piston ports were. Hop up articles for the piston port Yamaha CT1 and Suzuki TS400 have you make the biggest changes to the intake timing... For example the Don Vesco article has the CT1 intake port lowered 5mm for MX and an additional 2mm taken off the skirt for higher speed scrambles. The Modern Cycle TS400 article has the intake port lowered and the skirt shortened a total of 7.5mm. They say that the midrange was improved tremendously on the Suzuki and the low end was not hurt a bit.

But those are not MR175's! Impossible to know if it would be excessive intake timing without knowing what the port timing is now.

Don Vesco ! Havnt heard that name in a while. His brother Rick Lives near me and is a friend of mine. I grought the group over to his place In Rock Springs when the Enduro fest was here a few years ago . He Runs the Turbinator land speed car .
Rich

If idle infact does not work you could raise the intake port floor with epoxy the amount necessary , and any where inbetween

Rich

sounds like its worth the gamble. ebay has the ct1 pistons priced very reasonable compared to wiseco. Im thinking about trying that. t hanks