yz426f 4 ounce flywheel

5 replies to this topic
  • nofear14

Posted October 01, 2004 - 01:06 PM


I am going to buy a YZ426F and it has a lightened flywheel ( 4 ounces ) and I am curious what a lighter flywheel does :cry: ???

  • grayracer513

Posted October 01, 2004 - 04:48 PM


The flywheel, apart from being a component of your electrical system, adds to the rotating mass of the engine, and therefore, the inertia that mass has. You know how much easier it is to spin or stop a bare wheel as compared to a wheel with a tire mounted. It's the same thing in an engine.

An engine has 2 things to deal with as it tries to accelerate, the external load of moving the bike, and its own internal weight (I'm forgetting about friction, etc. for the moment). If you reduce the rotating mass of the engine it will rev quicker. The change in flywheel weight is most noticeable in neutral, when the engine's rotating weight is it's only load. It is also very noticeable in low gear, less so in second, and so on as the gear being pulled and the bike's weight become a bigger factor. In high gear, at near top speed, the difference between two otherwise identical bikes, one with a light flywheel and one with a heavier one, will be almost non-existent.

So, in situations where a quick burst of acceleration is needed, like coming out of a turn on a MX track, a lighter flywheel will help improve your jump. If you go too far with this, you end up with a bike like the stock '03 YZ450 at vaporizes the rear tire like a big two-stroke if it doesn't find enough traction. In that case, adding weight would help make the engine more usable.

  • Fastest1

Posted October 01, 2004 - 06:09 PM


And if you dont like it, it is easy and cheap enough to change it. :cry:

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  • nofear14

Posted October 01, 2004 - 06:28 PM


thanks guys

  • Chipstien

Posted October 02, 2004 - 07:17 AM


I am going to buy a YZ426F and it has a lightened flywheel ( 4 ounces ) and I am curious what a lighter flywheel does :cry: ???

Are you sure it is lightened or do you mean it has a 4 oz flywheel weight. :cry:

  • Fastest1

Posted October 02, 2004 - 02:53 PM


That is what I was thinking too! You dont hear of too many people lightening flywheels on the 426's but it could be fun with an auto clutch (offset the additional weight). When you buy the 426 if you dont like the lightened flywheel, put it up for sale here and I would buy it for the fun of experimentation. Hell the garage is full of stuff! :cry:

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