[hyperflow]

I just got a crf with a 490 kit, full FMF powerbomb exhaust, Quickshot, procom revbox and twin air filter.

Anybudy know what i should be running for jetting?

[nedirtbikr]

I have no idea on the jetting...but would really LOVE for you to post updates or send me PM's on how things go with the installation and how you like it overall after using it for a while. Good luck with that thing!

[Jethro]

i would also like to know how that works out for you. i have been curious and waiting for the opportunity to ride a big bore kit in a 450. i almost look forward to blowing my top end so i can try it. umm knock on wood....

[MadMatt]

I bet that hauls some serious Donkey! With those mods would'ent it have a jet kit already?

EDIT: a** changes to rear lol, rear makes me feel old

[hyperflow]

well thats the problem its slow, stock bikes are beating me. Im 1 bike lenght behind a stock 07 ktm 450sx

I was running a 170 main, called athena yesterday they told me to drop to a 160 main. We'll c if that helps i guess.

[MadMatt]

Are you loosing on top end or all the way through?

[hyperflow]

im faster up top from the other bikes, but by the time i would catch up the races would be over. Im running a brand new starcross in the back. Traction wasn;t the problem

[RJacks258]

One of the things probably needed is to lean out the main jet, pilot jet, and richen the air jet. With the big bore kit you now have more air being pulled through the carb so it's pulling more fuel through the existing jets than the 450cc engine would.
Another trick with the big bore is don't let it rev out so much. Shift a bit earlier.