300rman
04-10-2008, 12:25 AM
well, talking to the PR Racing engine builder, the 300 kit for the 84 and under R are not too good. there were a ton of reasons that he mentioned, ill list a few major ones.
1. ignition on it is perfectly designed to run at the rpm ranges that the 250 runs at.
2. the 2 best performing overbores for the 250 cylinder are .40 and .60 over. the .20 is better than stock, but the RPM's drop significantly at an .80 overbore. when you get an even bigger bore (the 300) the rpms are even moreso drastically affected. not so much how high it rev's, but jut the way it comes up to RPM.
3. of all the ways to get power out of your 2 stroke, high compression and porting are the best machinist mods you can do. he doesnt like bigbores at all.
this is all from his mouth, not mine.
also, that little shop has close to 300 national top-performing motors that out-perform all other shops. both 2 and 4 stroke.
he likes Duncan for their motor work, and respects them. CT (i think it was CT) is a joke, according to him. and some of the best 2 stroke pipes are the PT pipes. thats the brand pipe he recommends all day long.
i must say, i was checkin out a MILD (he claimed was their mild) port job done to, what looked to be a 125 cylinder.......it was wild as hell. i mean he had more channels cut into the sleeve, and....it was very unique, and looked like a performer for sure.
they also have this nifty cylinder from a 125 from back in the day, before water cooling was a wet-dream. they went and made a water jacket of sorts around the cylinder cooling fins, and rigged up a water pump (didnt ask how), allowing them to run tighter tolerances in pistons, rings, bearings, and therefore to make more power. it looks very slick for sure.
i will say this. when it gets time to rebuild my top end, i will be taking him my motor and having him build her up.
the coolest thing i heard was that he can tell you your main jet size to within 2 or 3 sizes just by measuring the port timing.
had a guy get a shee built up over there. came to get it, took a test drive in the lot.....he put the bike through the front window of the business next door. :lol:
discuss above statements.
1. ignition on it is perfectly designed to run at the rpm ranges that the 250 runs at.
2. the 2 best performing overbores for the 250 cylinder are .40 and .60 over. the .20 is better than stock, but the RPM's drop significantly at an .80 overbore. when you get an even bigger bore (the 300) the rpms are even moreso drastically affected. not so much how high it rev's, but jut the way it comes up to RPM.
3. of all the ways to get power out of your 2 stroke, high compression and porting are the best machinist mods you can do. he doesnt like bigbores at all.
this is all from his mouth, not mine.
also, that little shop has close to 300 national top-performing motors that out-perform all other shops. both 2 and 4 stroke.
he likes Duncan for their motor work, and respects them. CT (i think it was CT) is a joke, according to him. and some of the best 2 stroke pipes are the PT pipes. thats the brand pipe he recommends all day long.
i must say, i was checkin out a MILD (he claimed was their mild) port job done to, what looked to be a 125 cylinder.......it was wild as hell. i mean he had more channels cut into the sleeve, and....it was very unique, and looked like a performer for sure.
they also have this nifty cylinder from a 125 from back in the day, before water cooling was a wet-dream. they went and made a water jacket of sorts around the cylinder cooling fins, and rigged up a water pump (didnt ask how), allowing them to run tighter tolerances in pistons, rings, bearings, and therefore to make more power. it looks very slick for sure.
i will say this. when it gets time to rebuild my top end, i will be taking him my motor and having him build her up.
the coolest thing i heard was that he can tell you your main jet size to within 2 or 3 sizes just by measuring the port timing.
had a guy get a shee built up over there. came to get it, took a test drive in the lot.....he put the bike through the front window of the business next door. :lol:
discuss above statements.