Gains from flywheel?

[Quadjunkie]

What does one gain from lightening their flywheel? Are there some downsides to it?

[ryanh250ex]

there are no HP/TQ gains with a lightened flywheel. at least not that i know of.

What it DOES allow you to do is rev through the rpm range faster- less inertia needed to spin it to your next shift point.


the downside of it is that while you gain momentum quicker, you also lose it faster as well. you'd also be more prone to stalling.

if your build is a rev-happy one, it would be a great mod.

[interceptorz28]

I kept my stock flywheel on my z28 because of rotational mass. THe heavier stock one keeps the engine going fast once it is up and moving...... This is just what I have heard.

- i believe the lightened ones are strictly for racing applications which may have some downside to it.

[brokenmike]

I have a 8oz lightened flywheel,I did notice a difference when I put it on,it reved quicker,i did not notice it stalling any easier. I got nothing bad to say about it.I like it.

[1fst400]

I had one on my 416 motor that was alright. It made a diffrence in how fast the motor reved up. But would idle hard and stall if you where chugging aloing slow and hit a bump or somthing.

[red2004 TRX450R]

Originally posted by ryanh250ex
there are no HP/TQ gains with a lightened flywheel. at least not that i know of.

What it DOES allow you to do is rev through the rpm range faster- less inertia needed to spin it to your next shift point.


the downside of it is that while you gain momentum quicker, you also lose it faster as well. you'd also be more prone to stalling.

if your build is a rev-happy one, it would be a great mod.

I Know my father put a heaver flywheel in is drag car. Because of the increased inertia from a dead stop he would rev it to 8500 rpm and them pump the clutch the exrta wight would keep the RPMS up in the power band and would keep it from bogging down.

EX a fat guy running "350 pounds" and a skinny guy running "150". when meet with resistance "your self" the 350 pounder will plow through you and the 150 will be stoped or slowed down a lot.
but in a race they both have the same top speed. it takes the 350 pounder 3 seconds to reach top speed but it takes the 150 pounder 2 seconds.

now lets race - they both take off running and top out (clutch pulled in or flat land or ...) now they meet you wanting to tackle them.( dump the clutch , hill, turn ...) the 350 pounder smashes through you with little speed loss. but he 150 hits you and has slowed down a lot. there is another 20 yards to the finish. who wins the race?
I can't tell you.
you want to get a balance between to heavy and to light for your riding style, quad set up, racing type, rpm range, etc.


a heavy one will rev slower but is less effected by resistance (will want to stay where is at) and a lighter one will rev faster but will be more effected by resistance (will change where its at).

[deathman53]

I was explained that a light flywheel will accelerate faster, tend to spin the wheels more, stall easier and seam to make more power, a heavier flywheel will be more torquie, more controllable, won't spin so much, they also make you think the bike has less power, as it hits slower and more gradual.
I rode a trx250r with a 85 flywheel(lightest), 89(heaviest) and ricky stator lightened 200 grams over 85. The 85 was kinda middle of the road, not stall happy, but it took some time to get the speed up, 89 flywheel was very torquie, very hard to stall and kept the same speed through alot of stuff. The 200 gram lightened one, it revved fast, accelerated fast, but deccelerated fast and the power was kinda peaky, also stalled alot easier.
I have a cr250r igntion in mine, the flywheel is about half the size of the trx one, it revvs extremely quick, falls flat on it face very quickly too and its quite easy to stall. It is very good for mx, where its a race of how fast you can get from corner to corner, braking and acceleratign back out of the corner. But for xc use it would be horrible, stall alot and it would fall on it face through the obstackales. I am not using the cr ignition for comparism, just for a example of what a really light flywheel will do, as it has electonic timing, advanced timing and is computer controlled.
I would use the lightened one(but not too much) if you are only doing mx, if not, keep the stock weight one. The downsides for it on xc is too great and will tire out out. I only do mx on atv's right now, I plan to build a trx250r for the woods and will be using a 88/89 flywheel as the keep the tractability and as to not tire me out and keep stalling to a minimium.