Maintenance & Technical > KX450F / KX250F

Running 200:1 in your 4 stroke

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KXcam22:
I am toying with the idea of running a 200:1 or 300:1 fuel mix in my new 4-stroke.  The goal would be to provide additional valve guide and valve seat lubrication to extend top end life.  I have no worries about carbon since my KX power valve was clean after 400 hours.  I have heard about this before in race engines. What does everyone think??  Cam.

Arigato:
Good question.  I've always run a bit of leaded race fuel in my four-strokes, which is also supposed to prolong valve life.  What do all you smart people out there think?

Kev:
I have run car engines without stem seals to allow more oil to lube the shafts of the valves. I have only done this on engines that I was going for max rpm and was planning on tearing the engine down frequently, but I don't think you are going to gain any lubrication on the valve stem with oil in the fuel. The minimal amount of stem that is exposed during intake will probably be inconsequential. My concern would be the oil on the back side of the valve head. Those titanium valves get very hot and you would have a build up of deposits over time and that causes the valve to retain heat which is not what you want. It would most definitely have no lubricating effect on the exhaust valve as the oil would be burning. I think what you will notice most is a loss of performance due to the slowing of burn of your charge. Overall any results you get from this will most likely not be what you want. My two cents.
Kev

maddoggy:
i think arigato is on the right track with the leaded race fuel. probably mixing leaded fuel with your normal fuel would get you the benefits that you are after. however the extremely light 200 or 300:1 mix that you're proposing would be so light that i highly doubt that you would have any adverse affects on the firing. you just might achieve your goal with the lubrication properties. i guess you'll never know till you try it. if the bike was mine i'd try it. i really don't think there would be any risks involved. just my thoughts on the subject. MADDOGGY

maddoggy:
the company i work for recently did some testing of a product called DFC made by envirofuels the same company that makes the "rev r up" 2 and 4 stroke race fuel additive. it is a product made for diesel fuel intended to restructure the steel and impregnate the surface of the cylinder walls with a permanent lubricant. well long story short, about a million dollars worth of hailed out engines and hundreds of stuck injectors later we finally convinced our company to stop using the additive in the fuel. as soon as we stopped the additive our engine problems dissapeared David Copperfield style. i guess the moral of the story is don't use an unproven chemical product in your engine trying to improve it. Maddoggy

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