Race Fuel

[Flattracker]

I want to run 100% race fuel in my 98 KX 250 for many reasons:
1) For fuel Longevity for storage and cleanliness
2) Consistent formulation of fuel
3) Engine longevity / Help engine run cooler.
4) Carburetor cleanliness.
What type of fuel do you recommend for my 2 smoker?  Leaded verses Non Leaded? My engine is rebuilt with factory parts and is stock other than boyesen reeds and pro circuit pipe.  Any other Pros or cons I may have missed?
Also I have run HP2 synthetic pre mix oil (honda shop was real close) since my engine rebuild any opinions of this lubricant?

[reklessj]

If you have the cash and really feel you need to by all means go for it! VP C-12 it's leaded and two strokes love it. I mix it 50/50 with super pump

[dirk_411]

X2, exactly what rekless said. Haven't had an issue yet

[Foxx4Beaver]

keep in mind, if you run straight race...you'll have to completely re-jet for it.

might as well have the head re-shaped and run the "thin" head gasket too...this way, you'll get your money's worth outa the race fuel!

[treedodgingfool]

Ideally, stock engine KX's really like about 98 non-ethanol, preferably leaded octane. Because of OEM crank-seal issues with the ethanol in all the street-use intended pump in our region (E10, even when we mixed it at 50/50 with leaded race gas still was an issue with the amount of mileage our bikes accumulate), we switched to straight 110 leaded/off-road use only Cam-2 (same as Sunoco Gt 110 leaded; do not purchase the 100 octane non-lead, in ethanol states it has it).  In our immediate area (southern NJ), 110 leaded is readily available, consistent quality and reasonably priced.  Jetting will have to be drastically leaned out (specific gravity of race fuel is quite a bit lighter/flows better then pump, especially over pump with water asorbing ethanol), but I recommend going a step at a time until correct (higher compression along with race fuel is easier to jet, my KX300bb for example was a piece of cake to jet and was almost spot-on with me just guessing, but I'm running some pretty high-compression).  The benefits are huge!  The leaner jetting means superb fuel economy compared to pump, consitent performance (ever get a bad tank of pump? ping-city!), an increase in performance once properly jetted, cleaner powervalves, etc.  The only downside I've noticed on a stock-engine with race fuel off-road is when you have to lug it for a distance for transfer section (dirt roads, black top), race fuel is more prone to loading-up, but it clears out quickly and stays clear everywhere else when jetted correctly.  I would never use pump swill ever again in any of my racebikes since switching, race fuel isn't a hoax and is worth the cost. 

[don46]

If your going to buy race fuel for performance only go with oxygenated, but it sounds like thats not what your after. as for fuel longevitity, I don't think there is a good soloution for that, most of these high quality fuels have a pretty low flash point, take for example the MR12 is <100f and on a hot day you can actually hear it boil in your tank. I run many different race fuels, at the end of the day they are drained out of each bike and stored in a metal can with a metal lid, they can go bad in plastic cans as well. I've had some negative experiences leaving race gas in the tank and refuse to do it, especially oxygenated. Having said all this if I wanted a good all round fuel I would use C-12 and mix it 50/50, I have ran it straight in my sons 80 back in the day and it actually ran worse than with pump gas, to much octane and not enough compression.

[treedodgingfool]

We been using race fuel in stock & modded 250's/500/KDX200 (can't speak for 80/85's) for ages now.  Jetting is critical, once jetted for full race gas you can't use pump, even in a pinch, without rejetting (that much leaner).  4str's generally like oxygenated fuels, 2str's like lead.  As for storage of the fuel, granted we ride a lot, but we've had race-fuel (Cam2 110 leaded, similiar to VP C-12) sit for up to a month with no issues, but any bike in storage for months needs the tank drained regardless of the fuel, but especially for pump gas with ethanol (carb too).  I notice though, less nasty stuff/deposits are left behind in carbs where race fuel is used (taken apart a bunch of non-running/not idling 4str's with nasty crud left behind from ethanol-laced pump fuel that wasn't drained prior to sitting).