Mines fast enough for me, stock bore, GYTR full, K&n, open lid, jet kit, other cosmetics goodies.

 

I don't own a YFZ, but the fastest one I have seen was at Little Sahara, OK. It was built by Phil's Cycle in El Reno, OK. Curtis Sparks portwork, FCR carb (size=???), alcohol, stroker crank, 14.1 piston, Sparks cams, Sparks exhaust, extended swingarm...........................That's all the info I could pry out of them. It's a really fast bike, seemed very responsive. About another 8 bike lenghts or so and he could have caught the old QuadZilla..................[img]i/expressions/face-icon-small-wink.gif[/img]

 

The YFZ's that run out of St Joes park in MO are as fast as or faster than most that I've seen.

Don't blink. [img]i/expressions/face-icon-small-smile.gif[/img]

 

This is all good stuff! Thanks. It looks like after the exhaust, airbox, airfilter and then jetting is a cam mod. Does this mean "retarding" the cam or something totally different? I got some great info on an earlier post on "retarding" the cam I just want to make sure. I have also read a lot of posts that talk about a larger front sprocket?? What does this do for the bike? A different sprocket would just give you torque in a different part of the powerband correct?? This does nothing for more power or am I wrong? What size sprocket is good for most speed? What is a good brand?

On that last post: I ride at St. Joe a lot and I do not see a whole lot of fast YFZ's. However being a little bit newer to the sport I tend to not race a whole lot of people unless asked or it's someone I know. I see a lot of Banshees and a fair amount of Raptors, but almost all of the YFZ's are pretty bone stock.

 

What is an "ESR intake" system? I tried a search and could find nothing on the net?

 

It run good though. The mechanic told him to bring it back so they could finish up the top end jetting after he babyied it and broke it in. It run so good though he didnt bring it back.

 

The ESR intake is a formed aluminum piece that sits between the carb and filter . heres a link to the site http://www.esr250.com/default.asp
It removes the restrictive plastic intake that is stock and comes with a K&n Style filter

 

Thanks a lot. The web site helped. There is also a great reading about it on YFZ Central, which is a great forum for YFZ owners.