2T Racing Flywheel Weight
- Thread starter djroggen
- Start date
pscook
Platinum Level Site Supporter
Here's a question for the brainiacs- Say, for example, you made a FWW that had almost no mass in the center but lots of mass as far from the center as possible. What would that do for ROI? Would that make it easier to spin initially and harder to spin in the upper rev range? I remember that Suzuki (I think) created a crank for their GSXR 1000 that had almost no weight at the crank center but big heavy lobes further away from center. or maybe it was Honda. The trick was to make a physically lighter crankshaft that acted like a heavy crankshaft. Would that work on a 2T? I was thinking of making a bolt on Bronze one and trying it out. I ran a quick design on eMachine Shop and it looks like I could turn a 1.6 lb chunk and still have it fit.
Too big? (sarcasm)
But seriously, would a FWW with a large outer circumference work differently than one with a thick center and smaller diameter?
Too big? (sarcasm)
But seriously, would a FWW with a large outer circumference work differently than one with a thick center and smaller diameter?
GMP
Active member
Absolutely. Its all about where the mass is as well as the mass itself. If that new weight for the 2K-3 is only 8oz, and mounts like the other weights, I don't see a big increase in MOI compared to the 2K-3 flywheel. Now, done as Neil did it, at the circumference, would yield a much greater increase. I had a Cannondale with an aluminum SEM flywheel, very light even with the embedded magnets. I had a brass ring made and fit to the OD, maybe 12 oz. BIG difference.
This was done awhile ago by a member. The weights and MOIs are listed, but not the equation.
http://www.gasgasrider.org/html/flywheel_effect.html
This was done awhile ago by a member. The weights and MOIs are listed, but not the equation.
http://www.gasgasrider.org/html/flywheel_effect.html
pscook
Platinum Level Site Supporter
It looks like I could throw a lb of bronze on the flywheel and not overwhelm the engine too much. Maybe I'll source a small chunk and see what I come up with, moving the weight as far out as possible.
So my follow up question is this- Assume I build a FWW with as much of the weight as close to the circumference as possible, with a skinny center/hub, where will that weight be noticed? High revs or low revs?
GMP
Active member
A flywheel is as an energy storage device. Inertia of rest and of motion both come into play. Its rate of change or slope sensitive not absolute level of RPM sensitive. It resists change in motion(RPM) in either direction. This is all based on how the MOI number works out and the details of construction mean nothing by themselves. Hope this helps.
pscook
Platinum Level Site Supporter
Please note, I am not an engineer, so some terms may be inaccurate; ie: "pulling it out of my @ss." Correct me if I'm wrong, I will take no offense.
Then in theory, a larger diameter weight compared to a smaller diameter weight, all things being equal regarding absolute mass, the larger diameter weight would exhibit a potential to store more rotational inertia, thereby acting "heavier" to the rotational direction. And the smaller diameter weight, although of the same mass, would potentially be less likely to store rotational inertia than the larger diameter weight.
If I understand it correctly, I could make a large, but light, weight act in similarity to a small but heavy weight. The picture in my head is a merry-go-round with four kids on it. If the kids are sitting in the center, it's relatively easy to start and/or stop the rotation in comparison to having the four kids on the very edge of the merry-go-round.
I need to order some brass round stock.
Finally got some single track in with the weight and liked it. At first I found out my slide needed to lean out a clip because the extra weight made it take a bit to clean out. Was really surprised that would make a difference or I was borderline too rich and this made it more difficult to get on the main quicker. Either way I did notice a little difference but completely different than the YZ with the weight in it which was a huge difference. I need to do the head mod and I guess I have all the bottom end I am gonna get. The 300 is prolly the best enduring ever. My 14 year old rode it tonight and proclaimed I was cheating and the bike is the reason I am still faster than him...hard to disagree
After a little more time on it my observations change a tad. I normally ride 2nd gear in almost all single track. I was looking to have more power on demand off idle...which there was some change. What I did find is that I can carry 3rd more easily in most wooded situations where I would go between 2nd and 3rd.
Not sure I would do it again for the 90 ish bucks, but my sons yz250f with FWW stalls much easier than mine so I guess it is still a winner. Actually mine never stalls...rekluse...bah.
Not sure I would do it again for the 90 ish bucks, but my sons yz250f with FWW stalls much easier than mine so I guess it is still a winner. Actually mine never stalls...rekluse...bah.
GMP
Active member
The heavier flywheels are OK in the technical trails, but suck in the sand IMO. In sandy power sapping terrain the last thing you need is something else that dulls throttle response. For the most versatility, in different terrain like we have here in our race series, the light 2K-2 with a 12-14 oz weight and a G2 is a really nice setup on the GG250. Really depends on your needs, no right or wrong. The other thing is if stalling(on a 2stroke) is an issue, its likely jetting more than lack of flywheel weight.
Does anyone know if this new S3 Flywheel weight will fit a 2011 300 estart?
Scroll down to see the flywheel weight for kokusan ignition...
http://s3news.blogspot.com/
Scroll down to see the flywheel weight for kokusan ignition...
http://s3news.blogspot.com/
GMP
Active member
That looks very much like my 10 oz weight. It will fit onto the 2K-3 flywheel as it just screws on in place of the crank nut, but you may have a cover clearance problem. Not sure how much space that gear takes up. My 14 oz has a shoulder that wraps around the edge of flywheel and that will not fit. You can get weights like this from Gofasters, they have had them for years now. You guys wanting weights on 2K-3s should try my naked 2K-2 '12 250R with the JD Blue needle, wow!
Not a chance. The bendix assembly projects well below the outside of the ring gear on the flywheel. Very little room left and only a tiny weight could be added. It would barely be bigger than the flywheel nut and have no effect. I measured up everything and the only solution was the custom weight I made up.
The only way to add a weight is to remove the estart. You would have to replace the flywheel with an non-estart 2K3 flywheel in order to add a standard weight. You also would need the plain cover. GasGas flywheel weights are only intended for the plain flywheels.
