Lighweight GYTR flywheel any good?

[ttr250dude]

I have a 2008 YZ 450f with the GYTR heavy flywheel and love it in the woods. I ride some MX and am thinking about getting a lightweight GYTR flywheel. I would use the heavy one for trails and use the lightweight one for MX. How much will the lightweight help in terms of throttle response and adding more snap? Thanks, bill804

[grayracer513]

Don't bother. The difference it terms of engine acceleration between the two is unnoticeable, if it exists. Virtually everyone who has ever installed the "heavy" flywheel on a YZ450 has found that the bike looses no noticeable snap, but runs smoother and stronger at low end and gets slightly better traction under power with it. You will gain nothing by going lighter. IMO, it should have been built with the off-road flywheel to start with.

If your '08 is stock, the two best ways to improve the low and mid range power and response are to substitute an '06 CDI box, and replace or modify the restrictive stock muffler, preferably with a full system. Replacing your flywheel will only make your wallet lighter, and probably work against you.

[Gunner354]

I have a 2008 YZ 450f with the GYTR heavy flywheel and love it in the woods. I ride some MX and am thinking about getting a lightweight GYTR flywheel. I would use the heavy one for trails and use the lightweight one for MX. How much will the lightweight help in terms of throttle response and adding more snap? Thanks, bill804

They make one lighter than stock?

Never been a fan of heavy flywheels.

[grayracer513]

No, they don't make one lighter than stock. I'm frankly not sure if it would even be possible. Since you've apparently never seen the stock '06-'09 YZ450 flywheel, let me show you one, along with a familiar part for a comparison:

They do make two different GYT-R weights, however, which is what the OP was referring to. The so called "Heavy" "Off-Road" model has significantly less rotating inertia mass than the stock unit on either a 2010 YZ450 or a CRF450, and frankly, the engine as built from the factory has too little rotating mass. Several pro MX'ers have been adding flywheel weight to YZ450's since the first ones came out, and continue to do so. As I already pointed out, far more than 95% of everyone who has actually added one to a YZ450, as opposed to theorizing about it, has found it to be an improvement with no performance penalty.

[Mr. Neutron]

Hey, TTR250Dude!!!

Now, this is strictly an opinion here, and coming from an old guy. It may not mean too much..... These days, I ride more track than woods or trails. At the level I ride ("Amateur", or "B" Level, I guess..... ) I personally don't miss my lighter stock flywheel one bit. ? For the longer motos we ride at the Old Timer's National races (I think we ride 15 or 18 minute motos, but we ride 5 of 'em over 2 days), the smoother rev build up of the Off Road flywheel is much appreciated. ?

Again, this is only my opinion, but if you ride at a high enough skill level where you feel the heavy flywheel is holding you back, go ahead & get a lighter flywheel, or use the stock one, if you have that. Otherwise, save your money, or use it for more important things like tires, maintanance items, or a suspension flluid change....

Jimmie

[Gunner354]

No, they don't make one lighter than stock. I'm frankly not sure if it would even be possible. Since you've apparently never seen the stock '06-'09 YZ450 flywheel, let me show you one, along with a familiar part for a comparison:

They do make two different GYT-R weights, however, which is what the OP was referring to. The so called "Heavy" "Off-Road" model has significantly less rotating inertia mass than the stock unit on either a 2010 YZ450 or a CRF450, and frankly, the engine as built from the factory has too little rotating mass. Several pro MX'ers have been adding flywheel weight to YZ450's since the first ones came out, and continue to do so. As I already pointed out, far more than 95% of everyone who has actually added one to a YZ450, as opposed to theorizing about it, has found it to be an improvement with no performance

penalty.

Gray I really don't know what your beef with me is but yes I have seen a stock flywheel and yes I have ridden a 450 with a heavy flywheel and I am not a fan.

It appears that any other opinion than your own is subject to criticism.

[grayracer513]

That's a new development, since as of the last post in which you made any definitive statement about it, you indicated that your experience with heavier than stock flywheels was limited to quads and older two-strokes. Most people here don't understand your beef with heavier flywheels on a YZ450, since they measurably do not slow the bike's acceleration in any way.

You are entitled to whatever opinion you choose to have, but you are at considerable odds with the majority on this issue, and you know it. The fact is that the YZ450 was built with very, very little rotating mass, and in the opinion of by far most who have tried it, the engine improves with the addition of more inertia mass, and pays no penalty for it.

[gdbarr1976]

The only down side to a heavy flywheel is less stalling, more traction and easier to ride. Wait, that's not a down side.

[tech24]

+1 on keeping it, you'll never notice a difference in acceleration speed.

[rdefonce]

The only down side to a heavy flywheel is less stalling, more traction and easier to ride. Wait, that's not a down side.

That's what I'm hoping, since I just ordered one for my soon-to-arrive '10 model.

Perhaps I won't even have to do any "re-mapping" to soften the abrupt low end (that I've read about anyway) with the GYTR off-road flywheel installed . . .

[tech24]

That's what I'm hoping, since I just ordered one for my soon-to-arrive '10 model.

Perhaps I won't even have to do any "re-mapping" to soften the abrupt low end (that I've read about anyway) with the GYTR off-road flywheel installed . . .

It still hits pretty hard on initial throttle. The only difference I noticed was less stall in rough terrain. It wasn't enough for me so I added a z-start pro and the combo is very nice. But the flywheel alone helped a lot but I still prefered a tamer fuel map in the woods.

[grayracer513]

From the posts I've seen, it would appear that the only real fix for the abrupt tip-in response is the throttle body re-work from Injectioneering.

[tech24]

From the posts I've seen, it would appear that the only real fix for the abrupt tip-in response is the throttle body re-work from Injectioneering.

I would have to agree and believe me I have every other possible option: differnt throttle tube, gytr flywheel, mapping, rekluse. Its managable and something you really get used to however, but the throttle body mod would be a nice addition and give more tuning and tinkering options. (just can't seem to live without my bike for very long)

[rdefonce]

Interesting. I will read up on the throttle body re-work.

I have my trusty little 200 for seriously technical trails; the YZ won't be going there so perhaps I can live with it on more open stuff.