Lightening flywheel

[IcutMetl]

I ordered a flywheel puller and cover gasket; going to remove my flywheel and lighten it up. Don't have a toolpost for my lathe yet, so I may wait for that or have someone else do it. Those of you who have done it yourselves or have had it done, how much material did you remove from each face?

[Honda 250r 001]

i have a lightened flywheel by k&T and i can take some pics of how much material was removed to give you an idea if you want.

[IcutMetl]

Yea...that would be helpful. Thanks! If you (or anyone else) had a set of calipers handy to measure a lightened flywheel, I could compare it to what the stocker is.

[Honda 250r 001]

ill measure it for you also when i pull the cover off to take pics.

[86 Quad R]

you have a scale IcutMetl ? typically the flywheels offered by ricky stator are 200 grams lighter. you could use this info in conjunction with the size differences based on the one that Honda 250r 001 has and come with what you need.

if you have a scale, you can always take a lil off at a time and see what the butt dyno says. :cool:

another lil tid bit..... you can start out with a ATC fly wheel and not have to take quite as much off to get the same results. ;)

[IcutMetl]

Thanks for the info. I do have access to a small digital postal scale that reads in grams...good to go there. I have read that the ATC flywheel is lighter, but I figure...hell, if I'm going to dig into the case, I might as well do it to the one I already have. It'll be a cheap mod...cheaper than a CR250 ignition for now, just incase I want to throw lights back on it.

[86 Quad R]

be sure to keep us posted. i currently have the ATC flywheel and have been contemplating using a lightened flywheel on the next project. :cool:

[zedicus00]

85-87 flywheels fire at TDC.
ATC flywheels are 100 g lighter then trx flywheel
88-89 flywheels fire at 3 deg. advanced.

i cut about 300 grams off of a trx flywheel, not quite, actually closer to 280. i like the outcome.

i stck my flywheel on the flywheel puller really tite then chucked to the flywheel puller to cut the flywheel. worked great, if you have one use a live center.

[rsss396]

if you can find a bad crank that laying around the end could be cut off and chucked up

[thedeatons]

In my opinion it would be very helpful to take weight off the very outside edges.... Perhaps you could trim fat off the face where the pickup is for the timing....

The problem we saw in the Cannondale world (with flywheels) is that when people would lighten them they would throw the balance off. Cranks and bearings would go shortly after that, along with getting additional vibrations.

There is a guy up north who has balancing equipment, he balanced a lot of our entire Cannondale bottom ends (as a system). He could theoretically mount the 250R flywheel up, and see how it is balanced now, then lighten it and make sure the balancing stays the same....

The reason for this is because chances are Honda balanced the entire bottom end as an assembly. The crank and counterbalancer is setup together while the flywheel is mounted.... It should all be a balanced system.

Some of this may seem to complicated, the Cannondale guys love digging into this stuff and making things work better....

James

[IcutMetl]

When I get around to it, I'll figure out the best way to chuck it up, and use a test indicator to true the bore and face...that should bring it pretty f'in close I would think.

[zedicus00]

we dont cut the face, we cut the outer edge, like ricky stator.

ive seen cranks balanced together, flywheels balanced seperate, and some work perfect, some have problems. just depends on the engine.

[thedeatons]

The guy that did my Dale bottom end dynamically balanced everything. Balanced on the left and ride side...

The initial balance factor on the crank showed 350+ lbs of wobble force on ONE side. When he was done that side had 13 lbs of wobble force.

I put a lot of miles on that engine in my Cannondale dirtbike (on the street, plated, commuting to work). It was THE smoothest single I have ever ridden.

Some people do better work than others....

James

[86 Quad R]

a ton of great info guys. :) i have never really been a fan of removing stock from the face either. they are thin enuff as it is.

zed are you saying that its not benifitial to use the ATC flywheel as apposed to the TRX? :confused:

[Honda 250r 001]

hey man i posted a thread on the flywheel specs and pics...

[IcutMetl]

Cool, that's what I needed!

[Honda 250r 001]

Originally posted by TL250R
Came across this today:
http://www.duncanracing.com/buyersguide/hondatrx250r-b.phtml

$85 to mod flywheel

85 is way too much, flotek will do it for 40.

[Honda 250r 001]

Originally posted by TL250R
Came across this today:
http://www.duncanracing.com/buyersguide/hondatrx250r-b.phtml

$85 to mod flywheel

85 is way too much, flotek will do it for 40.

[headache]

yeah cut about 200 grams or so off of your flywheel. which translates into about 8 ounces. be sure that you get it indicated perfect in the lathe. If you cut off the face don't cut it too thin. i've done some flywheels myself with good results.

[IcutMetl]

Finally got around to cutting my flywheel in my lathe today. I indicated the face as close as I could (for being a stamping), then I indicated the tapered bore for runout. I removed approx. .200" radially, and about .030" or so off the face; trimmed down the steel hub as well right up to the rivets. Hopefully it'll dry up here sometime this week so I can switch them out and put it to the test on the butt dyno. I've read that the ATC wheel is lighter than the TRX to begin with. How much do they weigh from the factory?

http://i220.photobucket.com/albums/dd173/wlksjstn/flywheelindicate.jpg
http://i220.photobucket.com/albums/dd173/wlksjstn/flywheelturned.jpg

[headache]

it should work great. Good work!

[Honda 250r 001]

[QUOTE]Originally posted by IcutMetl
[B]Finally got around to cutting my flywheel in my lathe today. I indicated the face as close as I could (for being a stamping), then I indicated the tapered bore for runout. I removed approx. .200" radially, and about .030" or so off the face; trimmed down the steel hub as well right up to the rivets. Hopefully it'll dry up here sometime this week so I can switch them out and put it to the test on the butt dyno. I've read that the ATC wheel is lighter than the TRX to begin with. How much do they weigh from the factory?

Sheeeeit man, i hope she dont come apart. Looks pretty thin!

[derby]

Originally posted by Honda 250r 001
[QUOTE]Originally posted by IcutMetl
[B]Finally got around to cutting my flywheel in my lathe today. I indicated the face as close as I could (for being a stamping), then I indicated the tapered bore for runout. I removed approx. .200" radially, and about .030" or so off the face; trimmed down the steel hub as well right up to the rivets. Hopefully it'll dry up here sometime this week so I can switch them out and put it to the test on the butt dyno. I've read that the ATC wheel is lighter than the TRX to begin with. How much do they weigh from the factory?

Sheeeeit man, i hope she dont come apart. Looks pretty thin!

I wished I would have got to this thread before you cut it up. You are going to find that the balance will be off. If you don't mind a little extra vibes it should not be a big deal.

[IcutMetl]

And how is the balance going to be off??

On a side note; I weighed it tonight on a digital scale and it measured 994 grams / 2lb.3oz. I've read that the wheel is 2lb4oz to begin with...I thought I took off a good amount of material; where are Ricky Stator and other guys getting 200 grams from?

[derby]

Originally posted by IcutMetl
And how is the balance going to be off??

On a side note; I weighed it tonight on a digital scale and it measured 994 grams / 2lb.3oz. I've read that the wheel is 2lb4oz to begin with...I thought I took off a good amount of material; where are Ricky Stator and other guys getting 200 grams from?

I went through trial and error just like you did. You need a crank that you can cut the spindle off of. Mount the flywheel to it just like you were putting it on a bike. Then grab by the spindle. Basically you want to turn it between centers to keep the balance. Grabbing the flywheel by the inside or outside will not give you a balanced flywheel. Even using a spindle anymore removal than 120-150g and the flywheel will be out of balance.
The thing with being out of balance is not really critical, it will just vibrate more. The larger the stroke and piston the more vibration you will get.

The truth about the ricky stator flywheels is they are really only about 100grams lighter than a stock trx flywheel. In other words they are misleading buyers. I did buy one and then was going to attempt to lighten it and was disappointed when I weighed prior to turning. I confirmed the same wt with a local guys ricky stator flywheel that it does not weigh what they claim.

[Inspector]

IcutMetl, Derby is just about to being right on balancing. It would be great if you actually match it to the crank it self that you will be using. I used to do a similar process balancing pulleys on race car engines. We actually had a machine similar to a lathe where we could balance the crank with the pulley, and even the camshaft. Now, a CNC machine does it. VERY expensive process. I would be curious to how your system works. Please keep us posted.

[jon370r]

Kind of looks like mine that came apart a few years ago. I have done some since but gave up on cutting the front flange. The front on this one was about .080 thick. If I were you I wouldn't run that! Remember these are turning at 8000 RPM. Any weak point will show up eventually. The one in my quad now has been in there 2-3 years.

[All250R]

The weight that matters the most in terms of reducing the energy needed to get the mass rotating to a given speed is the weight furthest from the center of rotation.

[speedfreek]

I have been lightening flywheels for a while now from banshee's, cr250r's, trx250r and a yesterday I took off 15oz from a 400ex. That's 420gms!

I can see where they may need to be balanced but I have not noticed any extra vibrations nor my friends either. I "true'' them up to less than .005'' and I cut from every spot available!
400ex BEFORE
http://i90.photobucket.com/albums/k264/pnewell44/250R/400EXflywheel003.jpg

AFTER
http://i90.photobucket.com/albums/k264/pnewell44/250R/400EXflywheel008.jpg
http://i90.photobucket.com/albums/k264/pnewell44/250R/400EXflywheel.jpg

ESRcr250R Conversion BEFORE
http://i90.photobucket.com/albums/k264/pnewell44/250R/101_1393.jpg

AFTER
http://i90.photobucket.com/albums/k264/pnewell44/250R/000_0275.jpg

Like mentioned above, I cut the snout off of a bad crankshaft to chuck up in the lathe then the flywheel fits perfect.

I have a spare 400ex and banshee flywheel for sale, pm if interested.

[speedfreek]

If you look at the cr250 flywheel you can see a "L'' and an "H" on it. I marked it where the "low" and "high" spot was while on the quad so when I zeroed it on the lathe after turning when I put it back on the bike it was less than .0005 off. Before I have measured them and I have found from the factory some of them to be off up to .007

I am no professional at doing this but everyone that I cut my friends and I have loved.

I was told that on a 4stroke that I was going to lose a lot torque if I lightened it. So I lightened a spare one that I had lying around. I took off 10 oz and love the way it revs. It seems to have lost no torque. I liked it so much that I turned the other one down 15oz! I have not put it on yet but cannot wait to do so.

[All250R]

Originally posted by speedfreek


I was told that on a 4stroke that I was going to lose a lot torque if I lightened it. So I lightened a spare one that I had lying around. I took off 10 oz and love the way it revs. It seems to have lost no torque. I liked it so much that I turned the other one down 15oz! I have not put it on yet but cannot wait to do so.
Technically speaking you can't lose power by decreasing the rotational resistance the engine has to overcome.

[speedfreek]

Originally posted by All250R
Technically speaking you can't lose power by decreasing the rotational resistance the engine has to overcome. That sounds right. On another forum there were a lot of people speaking negative to me about lightening flywheels. I basically told them, if you've never done this mod don't say it's not going to make a difference. It is self explanatory.

I will lighten every flywheel on every bike that I ever own from now on because I love going fast! That's why they call me "speedfreek" lol.

[IRISH-RACER-14]

i wanna lighten my 300ex flywheel. is there any special method?

Your flywheel needs to be lightened or weight added based on the type of riding you are doing and the power curve you are looking to achieve.

Try ESR, Duncan, C&D Racing, CT Racing or BDT Motorsports for lightened or weighted flywheels.

[Honda 250r 001]

Originally posted by speedfreek
I have been lightening flywheels for a while now from banshee's, cr250r's, trx250r and a yesterday I took off 15oz from a 400ex. That's 420gms!

I can see where they may need to be balanced but I have not noticed any extra vibrations nor my friends either. I "true'' them up to less than .005'' and I cut from every spot available!
400ex BEFORE

AFTER

ESRcr250R Conversion BEFORE

AFTER

Like mentioned above, I cut the snout off of a bad crankshaft to chuck up in the lathe then the flywheel fits perfect.

I have a spare 400ex and banshee flywheel for sale, pm if interested.

What do you charge to do CR 250 flywheels? I want to get mine ligntened.

[speedfreek]

I don't have time right now but I have written several articles on lightening flywheels. Here are some pics of the ones that I did:
http://i90.photobucket.com/albums/k264/pnewell44/250R/400EXflywheel007.jpg
http://i90.photobucket.com/albums/k264/pnewell44/250R/400EXflywheel008.jpg
http://i90.photobucket.com/albums/k264/pnewell44/250R/000_0279.jpg

Here is the link to the pics and more:
http://s90.photobucket.com/albums/k264/pnewell44/250R/

[way2fast4u_250R]

your flywheels look great-i buy mine from 250rtrikes on fleebay for $100-i sent 250rtrikes my old flywheel, they gave me $50 core bucks-i get lightined 150 grams & balanced, looks new-mi flywheel has 3 diferent size small little drill holes around the wheel for balance-i do not try yet-mi friend has same wheel from 250rtrikes and he said he has less viration & more revs-

link for flywheel- http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=280542987909&viewitem=&sspagename=STRK%3AMESE%3AIT

i like your flywheel work-paul

[IRISH-RACER-14]

who are the best people to do this for best price for my 300ex and is it hard 2 take off the flywheel?

[quadrcr161]

what type of riding do yall do when lightening the flywheel? years ago i switched to a motoplat ignition with the little flywheel and hated it. on flattrack it would move but on tt it would hurt, either i was bogging off the corners or having to rev it and just spin the rears. yea it reved quick but it also fell on its face quick. like everything else has that equal reaction what go up must go down and without the weight it would drop rpm and power pretty quickly.

[Claas900]

I know this is an old post. I've never see or heard of some one lightning a Cdale flywheel. They weigh 565kg or just shy of 1.5 lbs. Also they are made of aluminum.

[jcs003]

this seems like the way to go:

http://www.davemooreracing.com/Flywheel.html

claims no loss of torque.