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03 first tear down since iv owned it. possible big bore

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I say might be big bore because i cant find my mic and check bore size against OE bore size.

Iv had this bike about 6 months and put plenty of time on it. Motor started getting loud so I packed it up. Tore the top end down and senior rod has some up/down play on the crank. No Bueno.

The number on top of the piston (10788m07200) I googled and got an old thread on a yz300.....I cant seem to find any parts listing on Eric gorr website. It's gonna need a piston, its scored more than I care for. I'm unsure if the cylinder is plated or not. How can j tell?

I im curious if i need to call Eric or is their another place I can look for parts? I'm not ready to order, I want to get an idea of pricing before I comit. Going to have to wait about 2 weeks before the Xmas bonus kicks in.

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In the garage sale section on the forward motion website they list a couple 72mm, 295cc cylinders.

I'm gonna call Eric and get info tonight...

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It's your lucky day!

Weeeee!

The head doesn't look modded either. I'll compare it to an OE one. Maybe reject for E85....

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Weeeee!

The head doesn't look modded either. I'll compare it to an OE one. Maybe reject for E85....

MX bikes cannot handle E85 the seals in the carb alone would all disintegrate from the E85. you shouldn't even run pump gas with 10% Ethanol. Ethanol free is the only gas you should put in one of these machines. I know this will probably get a bunch of people who say they use Ethanol gas with no problems but there is a reason that ONLY E85 rated cars and trucks can run the stuff. it is HIGHLY corrosive and will eat anything rubber or composite in your engine including seals, gaskets and the like.... do what you want, it's your bike, i'm just saying......

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I hear what your saying but have yet to see damage...ALL pump gas in Colorado is 10% ethenol...

E85 is cheaper and easier for me to get than race gas

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Found my Mic. bore is approx 71.5mm

I think that last # on your piston is indicating a 72.00mm bore.

And yes stock is 66.40mm.

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