Need More Power ASAP!!!

This is my first year in the Pro/Expert ranks and I've done pretty well in two races so far. But since I am bigger than the average rider (220lbs at 6'4) my powerful 4stroke is only keeping me even with the playing field. Last year on a 2001 YZ250 a KTM125 could run with me on a straight. This year on the 426 I was dead even with a CR250 on the straight. I am thinking of changing the gearing to allow me to get in the higher gears quicker, but what else can I do to get more power at a reasonable price.

I started running a 14 front and a 48 rear sprocket.The bike is much faster in the straights and it lost no bottem end power.

Nitrous oxide my friend. :)

I know there are a few big bore kits out there that will bump the displacement up to 444cc. I believe they're somewhat costly and your bike's reliability falls but that's a way to get some more HP. Do a search here on TT or Google and I'm sure you'll find something.

Good luck


I'd go with a Yosh or FMF Titanium pipe and header, and get an airbox. You might try checking into the Thumper Racing 450. I have ridden one and the bike hauls.


Buy a 520SX.....problem solved. :)

Jeez, if you think you got it bad, I race a YZ250F with the 520s and such in the Vet Expert class and I get waxed bad on the straights but eventually I find my way around them. I like telling them at the end of the race "it's a 250".

Too bad the 520 will be illegal with the 450 max being the limit by the AMA. Thanks for some of your suggestions, and I was wondering if anyone had the big bore kit from ProAction done to their bike and what they thought of it.

I have had Ty Davis on his 250F blow by me on my 426. I think that it is not more power that you need, but rather more experiance and skill. Have seen lots of gifted riders on stock bikes smoke posers on trick gear. Spend your money on rear tires and more time at the track.


Too bad the 520 will be illegal with the 450 max being the limit by the AMA.

Not for us Vets! Since you're 25, check and see if they have an over 25 class. Then you could ride anything you bring.

It sounds like the 4 stroke rule is working perfectly. Man if you want some power at a cheap price look up Eric Gorr his company is forward motion and he can probably set you up with a Big Bore kit for around $400. He does awesome work but doesnt charge as much as Rick Petersen and some of the other folks.

You may want to check on his work load though, it took like 5 weeks when I sent my 125 out due to a massive amount of folks dropping off their cylinders.

need more power try thumper racing they did my moter 452 ported polished head whit bros tapered pipe with pro meg with open end cap and went up 1 tooth in the rear all i can say is holly $h!# way way more bottom and same for the mid i dont hink it reved any more (about the same as before) but with MUCH more balls also BEWARNED!!! the bike also was about twice as loud not kidding (but still sounded good and deep)my friends complained all the time that bike bike was hurting there ears with there helmits on!!!no need to go inside on a corner to pass just get behind someone and pull the clutch in and rev the bike and the person in front of you just falls over works every time you think you hardly have to **** now wait till after the mods i was thinking of taking my shift lever off to save weight its not like i need it anymore

compression and head mods add lots. the compression makes a ton of bottom end. i ride a crf 450( don't make fun of me :) ) and i start in third gear and ride the whole track in third. i have a 13:1 comp ratio and a flowed head.

it pulls anything in a corner to corner drag race. i think these type of mods would make a huge difference on a yzf426. also i'm gonna buy a fmf ti4 exaust. i've heard it makes as much as 5 h.p. on the bottom and 3 h.p. on top. helps to stretch out each gear on those long straights.

hope this helps you out. :D

Nitropropane, just make damn good and sure you got your jetting right.

You can just pour the horsepower right into the tank.


I run a 444 kit from Eric Gorr with a ported head and EVO pipe.

With 13.5:1 comp ratio it won't over-rev as good but if you're after serious mid-range that's the way to go, I went back to 12.5:1 to make it rev higher, still much more torque than stock.

You will need to warm it up, the cast piston don't like to be run before it's up to operating temp.

My 444 kit is for sale, I paid $500.00 USD including the price of the cylinder (actually the whole bike is for sale, a 2002).

Traid it in on a new CRF !!

Hey Ego,

You wanna take this one...

Thumperpwr has got to be told the truth about power. :)

I hope he's just kidding!

Ride On......


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