Gearing

[konastank]

I've got a race coming up where I need waaay more top speed. My friend on a KTM 525 is running in 4th and 5th gear the whole track, and he was the fastest rider in praccy. My quad tops out about halfway thru his 4th gear. I need to be able to get to the same speed as him. I'm on 18s running 15/38 gearing. I'd like to run as if I was on 20s or 22s. Any recommendations?

[brokenmike]

What do you have done to your quad and how much do you weigh?

You either get a 16 tooth up front, or drop 3 teeth on the rear sprocket.

[shawn3389]

i dropped 2 teeth in the rear and its way faster now, i can pass my buddy on has kfx400,i'm in 2nd and he is in 3rd this was on a track too

[Snipe]

Go up 1 tooth on the front = going down 2 on the rear.

bring that front sprocket up highest you can go is a 16.

Bring your tire size back up to stock with 20's on the rear.

More air is better running a track run an open air box with a UNI or K&N filter with a decent after market exhuast.

Put an advanced timing key in.

Drastic just to be faster but Have a 440 kit put in with a stage 2 hot cam with a high compression piston (stay under 13:1) as anything 13:1 or bigger has to run race fuel and i believe its recommended a stage 3 cam for high compression pistons.

[NacsMXer]

Originally posted by SuicideMFNdoors
You either get a 16 tooth up front, or drop 3 teeth on the rear sprocket.

I agree, simplest way to go about it. Either go 16/38 with the 18's out back for a 2.38:1 ratio (you will have MUCH better top end but your low end will suffer), or go with 15/36 gearing for a 2.40:1 ratio (this will accelerate slightly quicker).

Right now at 15/38 gearing you have a 2.53:1 ratio, so going to 16/38 or 15/36 will be a drastic improvement in the top end.

[Pipeless416]

Originally posted by Snipe


Drastic just to be faster but Have a 440 kit put in with a stage 2 hot cam with a high compression piston (stay under 13:1) as anything 13:1 or bigger has to run race fuel and i believe its recommended a stage 3 cam for high compression pistons.

anything above 11:1 needs to run higher octane than pump gas.

[Snipe]

From what I have read on every website its anything higher than 12.5:1 needs to run more than gas pump.

Even your stock motor suggests running super instead of just plain unleaded.

[NacsMXer]

Originally posted by Snipe
From what I have read on every website its anything higher than 12.5:1 needs to run more than gas pump.

Even your stock motor suggests running super instead of just plain unleaded.

With how hot these motors run, I consider 93 premium to be the bare minimum at 11:1. If anything I would run a 50/50 mix with race gas. On my motor running 12.5:1, I run nothing but straight 110.

If it is recommended in the manual to run "super" 91/93 with a stock 9:1 compression ratio, then anything above that will require even higher octane.

[konastank]

Right now I'm running a 426 bore at 12.5:1 comp., Full exhaust, K&N intake, xr400 cam. I've got a ton of low end power so I can sacrifice low end no problem. I will probably try a 15/36 and 15/34 setup and see how they work out. I'm keeping the 18s on. I'm light too I weigh 150