About Flywheels.........

2 replies to this topic
  • 707

Posted October 31, 2004 - 02:26 PM


If you put a lighter flywheel on it will have more hit? What does putting on a heavier flywheel do?

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  • John407

Posted October 31, 2004 - 04:43 PM


Yes, if you put a lighter flywheel on it will allow you to increase the revs faster. It also may stall easier and yes the hit also is increased.
A heavier flywheel will make the motor rpm increase slower and tames the hit.

  • grayracer513

Posted October 31, 2004 - 04:59 PM


Apart from being an element of your electrical system, the flywheel adds to the rotating mass of the engine. Just like when you compare spinning a wheel without a tire on it to spinning one with a tire on it, the heavier one is harder to accelerate, and harder to stop.

If you have an engine with a light overall rotating mass, like the ’03 YZ450, and you try to do a lot of low speed trailing, it will likely stall fairly easily. Increasing the flywheel weight makes it less likely to do so by adding more rotating inertia to the engine.

Taking the same bike as an example again, many people find that the engine accelerates too abruptly at low speeds, and that this makes it difficult to control the power output. Adding flywheel weight gives the engine more work to do in accelerating its own mass, and thereby takes a little bit of the snap out of it.

Ultimately, the thing that makes the power is not the flywheel, and putting a lighter one, or a heavier one on an engine will neither add nor subtract horsepower or torque. Changing the flywheel weight will have the most effect in neutral, where it is pretty much the only load on the engine. In gear, it will be most noticeable in low, and make progressively less difference as you increase the gear ratio, because the flywheel weight will become a very minor percentage of the work the engine has to do. Two otherwise identical engines, one with a heavy flywheel, and one with a light one, will act much differently coming out of a tight turn with poor traction, but they will accelerate nearly identically in fourth gear, and have the same top speed.

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