how to cure a low top speed

08kawi450 · #1 (**permalink**) 03-07-2010, 11:12 PM

I have an older brother with a new yfz450r. He has trinity full system, air filter with a billet adapter and efi controller. I have an 08 kfx450r with a 13" dasa full system, the new K&N intake system and an FMF power programmer. Ive tuned it the best i can with out a dyno but we'll drag race and he'll beat me in top end every time.

I can take him through about fourth gear but once we hit fifth hes gone. My question is what can i do to fix this problem cheaply. I want the top speed i just don't want to lose my low end torque. Also i have stock sprockets on right now. Anyones help would be awesome. Thanks

6789olds · #2 (**permalink**) 03-07-2010, 11:24 PM

a 15 tooth front sproket should help out . or a 36 tooth rear

kawi_34 · #3 (**permalink**) 03-07-2010, 11:51 PM

Yeah gearing is one option. Maybe a different intake, like the FCI intake. You just have to browse around the forums and see whats out there. You will get different replies on this but there are alot of smart guys on here that can give you good ideas on what to do. Goodluck man!

georgiakfx · #4 (**permalink**) 03-08-2010, 12:12 AM

When I switched to the 15t front I gained a few mphs and I still can take anyone on take offs. I like the 15t way better than the 14t, for the money you can't go wrong.

nkeen07 · #5 (**permalink**) 03-08-2010, 12:27 AM

15/37 gearing. I love 15/38 myself...but either will help you a lot w/o losing bottom since you have the big three already.

Dust Devil · #6 (**permalink**) 03-08-2010, 12:23 PM

Quote: Originally Posted by 08kawi450

I have an older brother with a new yfz450r. He has trinity full system, air filter with a billet adapter and efi controller. I have an 08 kfx450r with a 13" dasa full system, the new K&N intake system and an FMF power programmer. Ive tuned it the best i can with out a dyno but we'll drag race and he'll beat me in top end every time.

I can take him through about fourth gear but once we hit fifth hes gone. My question is what can i do to fix this problem cheaply. I want the top speed i just don't want to lose my low end torque. Also i have stock sprockets on right now. Anyones help would be awesome. Thanks

Rev X-Tend
On select models of bikes our Rev Xtend feature is available when using the Ignition Module. Rev Xtend makes it possible to increase the RPM limit from the factory setting. This feature is intended to be used on engines that have been modified to allow the increased RPM limit.

Ignition Module, Power Commander Ignition Module

Or a good 3 or 5 angle valve job and porting will help.

KAWASAKI

More horse-power= more speed...

Also...

http://extremegarage.com/techtips/gearratiosfaq.htm This will help with figuring out gear ratios...

**ononewheel** · #7 (**permalink**) 03-08-2010, 02:53 PM

a 15tooth front for sure cheap way to gain some top end w/o loosing bottom end!i also did a 36 rear which is good to but i think the best combo is 15f 37 rear and maybe go w/a pc3 instead of that fmf power module!

Duster · #8 (**permalink**) 03-08-2010, 04:48 PM

Oh... now we have someone with the K&N intake system.
You'll have to review that for us...

Yes, you'll want to pick up a 15t front to gain some speed.
Gears pull longer between shifts and top speed is higher.

If you have yet to do tires, that will make a huge difference also... in fact, it should be done before any of the big 3 stuff. But if it hasn't yet, do it.... and there is always the option of 21" tires in the back.

If you have the power to pull it (and you should) +1 tooth in front is worth +5 MPH and +1" on rear tires is worth +4 mph.... +9 MPH total.

-1 tooth on the rear is worth +2 MPH if you have tires and are going that route.

I think if I end up staying with the Holeshot GNCC pattern on mine, I think I am going to go to 15/39 with 21" rears.

08kawi450 · #9 (**permalink**) 03-08-2010, 09:13 PM

i have holeshots all the way around. stock size but i like them alot it really improved the handling and the twitch in the front end. I have a 15 tooth front alread ill just try puting it back on. I didnt have the big three when i had it on. I just had a two brothers slip on and a billet adapter and k&n filter. Now that i have the big 3 ill try it again. I apprecitate the advice guys. Thanks

08kawi450 · #10 (**permalink**) 03-08-2010, 09:18 PM

Also reveiwing the K&N intake system. Ill be going to waynoka, OK to the sand dune at the end of march. Im getting it dynoed. Ill be able to give you guys the hp info and everything else. Also going to have them tune my efi programmer. They'll be able to tune it a lot better than i can with out a dyno.