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DYZFatCat

WR450 Flywheel Modification

12 posts in this topic

I was wondering if anyone could recommend a place that they trust to send a WR450 flywheel to for making it lighter. From my understanding is that the A YZF with a 8oz flywheel still doesn't come close to the weight of a WR flywheel. I also know that where you take off the material on the flywheel matters as well. I need someone that knows what they are doing. I am looking for a little more hit and I have done all the normal mods like FMF TI4 powerbomb exhaust system, YZ-cam. I am doing a lot of MX and desert. I dont need the YZ 450 beast motor, just a happy medium. Thanks. Damon

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I pulled my flywheel and had a riding buddy who works at a machine shop machine 2.5 ounces off the outer surface. There is a noticeable increase in the snap when the throttle is opened, especially from the lower-mid rpm range and up.

Much of the mass of the flywheel is composed of the magnet. The outer jacket that encases the magnet is only about 1/4 inch thick and is the only part that is easily machinable. We machined off as much as we thought would be safe without risking an exploding magnet at high rpm. Last weekend I had the bike up 75 mph (w/ a 13 tooth countershaft sprocket) so it was revving high, and the motor still felt well balanced. On that same ride I probably crossed/jumped 400 fallen trees and noticed the motor would develop torque quicker to lift the front wheel. Usually no clutch needed.

To pull the flywheel we had to make a wheel puller. My machinist buddy used to ride a YZ400 and had wheel pullers, but the WR requires a wheel puller that engages threads on the outside diameter of the flywheel, instead of threading a puller into a threaded hole.

I am happy with the result and it only cost me some beer, though I am considering additional steps. The next step would be to drill some material from the backing near the inner part of the flywheel. I have some concerns about wheel balancing with this approach. And I don't think there will be much gain from removing material near the axis of rotation. There just isn't much that can removed near the outermost portion of the flywheel. Once we had the wheel off the bike, it only took about half an hour to do the machining.

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Thanks for the info. I found out the sister of a friend of mine in Phoenix has a metal shop that does custom work. I just need to find out if they will do this.

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You've got an excellent machinist right there in Sahuarita. His name is EK Ongley, don't know the name of his shop, but if necessary I can find out for you. He's an ex-ADRA racer and knows bikes..... :)

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Thanks Rich! I tracked the name down on the Internet and found his business address and phone number. :D He is about 3 miles from my house. The internet is scary isn't it. :) I will give him a call and see what he thinks. Damon

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To help let the bike spool up quicker make sure your lights are off. The drag from the magnetic field in your stator cost hp.

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Is this the only alternative? Doesn't anyone make an aftermarket for this? I would be interested if so. I already know Trail tech does not have one for the wr450.

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Is this the only alternative? Doesn't anyone make an aftermarket for this? I would be interested if so. I already know Trail tech does not have one for the wr450.

Well the post was talking about a 03' WR and taking off flywheel weight which is useless IMO. Send your carb in to Zipty Racing and get all the mods. No downsides only more tractable useful power.

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I'm always looking for ways to make my wr snappier. I had a ride on a wr that had a flywheel that was 5 oz lighter than stock and it was snappier that before. I don't want to go the route of machining it down I would'nt trust it. As far as the carb mods already done it ! The bike runs great, I just like the arm wrenching acceleration.

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I'm always looking for ways to make my wr snappier. I had a ride on a wr that had a flywheel that was 5 oz lighter than stock and it was snappier that before. I don't want to go the route of machining it down I would'nt trust it. As far as the carb mods already done it ! The bike runs great, I just like the arm wrenching acceleration.

I've never got arm wrenching acceleration from less flywheel. Most people want more flywheel not less unless your riding on the street.

Edited by stevethe

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I'm always looking for ways to make my wr snappier. I had a ride on a wr that had a flywheel that was 5 oz lighter than stock and it was snappier that before. I don't want to go the route of machining it down I would'nt trust it. As far as the carb mods already done it ! The bike runs great, I just like the arm wrenching acceleration.

 

Yes, but torque is what you use to accelerate on all surfaces, not just flat.

If you lighten the flywheel, you will have to down shift more for hills, and you will spin your rear tire faster.

You will NOT make any more hp; you will make the hp you have faster to get to.

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