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The Italian Stallion

heavier flywheel on 06450

5 posts in this topic

I am one of the very few on blue in a sea of red at my local track. I have ridden so many crf450s I could not count them all. me and the honda guys say the same thing.The Honda has more grunt down low,and the YZ is stronger mid and up. I like the YZ engine more after riding the YZ the honda powerband feels really short but I do like the low end grunt. Can I get this with a heavier flywheel without f...in up the yzs strong points? From what I remember the 426 had more low end grunt than the current CRFs

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Adding flywheel weight will not increase low end power.

Yeah I should stay off the computer while drinking brandy:bonk: [how could adding weight increase snap?]I ve never messed around with flywheels. My understanding of why peaple put them on is so there bike won't stall because of the rotation of mass keeps the engine spinning when you let off the throttle.And wouldn't that make it easier to get back into the meat again since the engine is not slowing down as much? [maybe I should shut up I am sober today] Educate me if you will grey on the effects of to light of a flywheell:prof:

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Increasing the flywheel weight increases the rotating mass of the engine, which increases the inertia of the engine. This does two things:

> You mentioned this one; it helps prevent stalling. This is easy to understand. Anyone who's ever fooled around with wheels and tires knows this. The wheel is easier to stop spinning without a tire on it than it is with one. The heavier assembly will be more likely to keep spinning if you drag your fingers over it. An engine does the same thing. With a heavier flywheel, the extra inertia will help pull the engine around to the next power stroke in spite of running at low speeds, and make it a little harder to kill with the brake pedal.

> Control wheel spin. Just as the wheel above is harder to stop with a tire on it, it's also a little harder to accelerate. You can turn it just as fast as the light one, but not quite as quickly or easily. The same is true of an engine like teh '03 YZ450. As delivered, it's far too quick revving off idle to be reasonably controllable (opinions vary, that's mine). Under most circumstances, the bike would be much easier to ride, and get better traction if it didn't require so much concentration on throttle control and break loose so easily. On these, a heavier flywheel helps by giving the engine a little more work to do, a little more mass to accelerate. The result is that the bike that once sat at the end of a corner and dug a hole now lifts the wheel and disappears uptrack in a hurry.

But, there are also bikes that don't need this, and from a performance standpoint, maybe shouldn't have it. IMO, for MX, my '06 needs a heavier flywheel like my sundial needs a lube job. It's much better on power delivery as it is, and the weight might take a little quickness away.

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I tried the heavier GYTR flywheel on my 07 YZ450. It was great for trail riding. I don't recomend it for the track. If you want more low end I just added a Pro Circuit TI4 GP pipe and the throttle response and bottom end are really awesome.

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