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Building new motor
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Posted by: 87250rspell

This is the first big bore that I am going to build and i have a few questions. I found a great deal on a brand new esr 350pv and a brand new 4mm stroker still in the boxes. What kind of machining has to be done to get these to fit. Where is the best place to get the machining done. I live in kansas so i have NMotion close but i wasnt sure. Also with the 350pv and the stroker how big will this motor actualy be. One last question the cylinder has type 9 porting which i believe is midrange which should work good with my trx5 centermount exhaust, am i correct? Sorry for all of the questions, but i need a little help. Thanks

Posted by: 250r4life

yes that is correct- that mid range porting will match up good with your mid range pipe...

just a note... i would consider replacing your gears with some new ones or HD ones, or getting them kryoed or whatever it is... especially 2nd gear... if youre launching in 2nd gear, that power is going to put a lot of stress on it...

obviously you should beef up the clutch as well...

Posted by: 87250rspell

yeah the motor will be new from top to bottom. I think yukon made heavy duty gears but i cant find them anymore. Does anyone know were to get them

Posted by: 250Renvy

There's a guy on ebay : User is Rebadew or you can search the name R leftover parts. He usually has a old stock Yukon gears for $299 -$349

Posted by: wilkin250r

You can't always mix-and-match components. If the cylinder has already been ported, it may not work properly with the 4mm stroker.

The stroker crank changes all the port timings. When using a stroker, you need to get a cylinder ported specifically to match it, and correct all those timing issues that the stroker throws out-of-whack.

Unfortunately, if the cylinder has already been ported, it CAN'T be used with a stroker. Too much material has been cut away, the port timing cannot be corrected to match the stroker.

Posted by: tx_250r

if you really want the stroker talk to c-leigh he told me he could port my 310 trx9 for a +4mm crank.