KX 250 F Flywheel

[steelhorse]

Hello, Maybe somebody can answer a couple of questions for me.
I want a heavier flywheel for my 2008 KX 250F for better trail performance (we all know the benefits).
When looking at the Kaw "parts" manual (generator section) I see three flywheels listed, stock(noted I=4.1), a lighter one(I=3.6) and heavier one(I=4..
  When I contacted my dealer service department they told me that the (I=) designation was for Kilograms. When doing the math in seeing how much weight I'd add by installing the heavier one the answer was an increase of 24.7oz or 1 1/2 pounds.
  I question the (I=) value my dealer told me because Stealey Off Road offers two heavier than stock flywheels with the heaviest being 6oz due to size constraints in the side cover.
  Anybody have usuable information to assist? Can anyone make a recommendation from their experience?

Thank you!
steelhorse   

[Friar-Tuck]

 Steel,
  I would be very surprised to find  "I" in any terms for weight, I've been surfing around trying to find that and have no luck.   Maybe someone else knows.
     You're definitly on the right track,
         Tuck \o/

[snoopjonnyjon]

I is the mass moment of interia.

The way a flywheel works, the weight/mass really isn't the sole determining factor. You also have to consider the distribution of where the weight is located from the rotating axis. The Kawasaki flywheel would probably add the weight more towards the outer circumference (since that is where it is of most benefit if you are engineering an entirely new flywheel), while the Steahly adds weight to the outer face, which will require more weight to accomplish the same thing.

[steelhorse]

Thanks for the replys. I see I made an error in my post having put a smiley face instead of the important I=4.8 for the heavier flywheel.

Friar-Tuck, Thanks for the encouragement!

Snoopjonnyjon, As for you description I believe you entirely correct. The Kaw parts manual illustration shows exactly what you describe. That is, a peripheral collar ring on the flywheel located toward the back of the flywheel.   

My question now becomes, does anybody have riding experience with the heavier optional Kawasaki specific flywheel? Cost by the way is $202us.(through Cheap Cycle Parts on the web)

Thanks all!
steelhorse 

[blaisintreez]

i have a rm250 port and polished on race fuel with 13oz weight, works well for moto i would not want a bigger one , hope that helps

[ktmdude]

I have an 11oz steahly on my 01 kx250, I like a lot. I can ride slower over rougher stuff easier with less clutch work. It doesn't snap quite as hard, it reves up a bit slower, but is more "rideable". It comes with a 1/8 in spacer, for clearance with the side cover, but it only came with one gasket. It was simple to install. I recommended the engine lock out tool that they sell. If you are crafty you can make one out of an old spark plug. You screw a bolt threw the center of the old plug, insert the plug tighten the bolt until it contacts the piston, that will allow you to remove the nut on the fly wheel. Replace the nut with the weight, put the cover back on and you are ready to ride. It cost me something like $115.00 so if money is tight, look into steahly, its a good product. I would definitely put one on a bike I was setting up for woods.