YZ250 Cylinder porting

Tombstoneman34
Edited Date/Time 12/6/2012 1:11pm
Had to buy a new cylinder this summer, now I'd like to have some porting done. Considering sending it to Pro Circuit. Has anyone had theirs done by them? Any other suggestions as to where to send it?
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slipdog
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slipdog 11/21/2012 3:31pm
11/21/2012 3:31pm Edited Date/Time 11/21/2012 3:42pm
Send it to the Pro-Action headquarters in PA.

They built a Transworld test bike back in '03 and Rich Taylor said it was the best yz 250 motor he tested, and he even tested the factory bikes. The motors haven't changed since then.
Jakes Dad
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Jakes Dad 11/22/2012 3:02am
11/22/2012 3:02am
Give my guy a call, motors haven't changed but technology has. He uses several different computer programs for porting and head designs. A lot of builders are one dimensional in their theory, Brent builds racing snowmobile, dirt bikes and road race 2 strokes. www.tdc2strokeperformance.com
Mxfan
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Mxfan 12/2/2012 10:33am
12/2/2012 10:33am
Had mine done at Pro Circuit. The exagust port was nicely polished. The intakes were quite rough. They left casting imperfections all through the transfer ports untouched. Spent a lot of time sanding them out. The people up at the shop are great. I didn't contact them with my dissapointment, and I don't know if they changed any of the port timing. Good luck.
DTHA70
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DTHA70 12/6/2012 11:57am
12/6/2012 11:57am
Mxfan wrote:
Had mine done at Pro Circuit. The exagust port was nicely polished. The intakes were quite rough. They left casting imperfections all through the transfer ports...
Had mine done at Pro Circuit. The exagust port was nicely polished. The intakes were quite rough. They left casting imperfections all through the transfer ports untouched. Spent a lot of time sanding them out. The people up at the shop are great. I didn't contact them with my dissapointment, and I don't know if they changed any of the port timing. Good luck.
they left the intake rough for a reason, it helps with fuel atomization.
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Jakes Dad
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Jakes Dad 12/6/2012 1:11pm
12/6/2012 1:11pm
Yeah casting flash is good for that.Whistling
Sm450R
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Sm450R 2/11/2026 5:46pm
2/11/2026 5:46pm
slipdog wrote:
Send it to the Pro-Action headquarters in PA. They built a Transworld test bike back in '03 and Rich Taylor said it was the best yz...
Send it to the Pro-Action headquarters in PA.

They built a Transworld test bike back in '03 and Rich Taylor said it was the best yz 250 motor he tested, and he even tested the factory bikes. The motors haven't changed since then.

I know this is a very old forum but I have a PA ported cylinder but I can’t find jetting specs anywhere for the porting work. I have it very close to perfect but I wanna be sure going leaner won’t cause any harm.

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