1) Learn how to adjust the suspension for the conditions
2) Learn how to adjust the jetting for the fuel you are running and the weather/riding conditions
3) Learn how to adjust the valves and change the piston and rings
4) Run a fuel that will vaporize at high engine speeds like the oxygenated fuels from Phillips, VP and Nutec
5) Keep fresh tires on it
Rich... Are you able to be a little more specific on the fuel? Im kind of a heavy guy for my 250F. If mixing a little higher octane fuel with my pump 91 would help I would be all over it.
Phillips B35 now called Track Tech 101 (good price/performance balance)
VP Ultimate 4, MRX, or MR1
off the top of my head I don't remember the Nutec 4 stroke fuel name (I don't use it)
Another quick one for you. After posting earlier I did a net search for Nutec. I found a article at TWMX that sounds impressive. On to my question.... When using these fuels do you need to rejet or make any other adjustments.
I know there have been many threads on high octane fuels. They all end up in technical debates. Im just looking for a down and dirty answer.
Jeff: i would look around for the VP fuel, ultimate 4 its quite popular around here. the Nutec stuff isnt cheap and its much harder to find.
to add to Rich's answer, the new wave of 4-stroke fuels have what is known as oxygenates- these will make the bike run leaner and so generally, you will have to run richer jets to compensate.
This is really great information and couldn't be any more timely for me.
I just picked up a used '02 YZ250F from a Kayaba suspension tuner. He'd been running VP4 (I think) and the thing ran like a rocket. The three times I've ridden it, I've just been adding 91 pump gas to the tank.
Because I only ride 2 or 3 times a month, I don't have a big problem paying a little more for 5 gallons or so per month... Will it really help using the VP ultimate 4? And if so, it ran so well before, I just need to keep an eye on my jetting?
Mike: if it was setup for then U4 it might run a bit rich on the pump stuff- maybe ask the guy what he did with the jetting.
if you are going to run the expensive race gas, try and keep it in the drum and buy a smaller 2 gallon plastic fuel jug to transport just enought gas to the ride- its also well worth draining the fuel out after the ride for storage in that smaller container.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.