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Flywheel Lightening

Old 08-27-2012, 02:51 PM
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Originally Posted by autoteach View Post
we have a shop by us that balanced our snowmobile flywheel we made. They do spin balancing up to 20krpm or something like that. Luckily, they are also a customer, so it was easy to swing.
I wish I had that resource.. the only place I found willing to do the job was a Lab, normally dealing with some VERY high tech armatures and rotors.
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Old 04-19-2013, 11:32 AM
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Flywheel #16

Turned out another one today....

Starting WT 7lb 5 5/8oz
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Finish WT 6lb 2 1/8oz Reduced 1lb 3 1/2oz
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Received 1400 18 APR 2013
Boxed and in the mail 1330 19 APR 2013
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Old 04-19-2013, 11:53 AM
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Some may have noticed the final weights are all over the place...
And they are.

Some of that is due to starting weight. But most of it is the different ways i have reduced weight, where and how far I cut.

When I do the Roger Ditchfield 146 OD, 10.5 wide.... I get a very close final wt between examples. (starting wt and if the part has balancing holes drilled in it effect the final wt... Not all have holes drilled, or the same amount drilled out when they do)

The rest of the differences are accounted for when I turn the OD down, the width down, or both.

This example is 138mm in Dia, 10.5 wide. 6lb 2 1/8oz final wt.

I can take a few more mm off the width, but it makes the lip that locates the sprag clutch a bit thin. 9.5mm wide is as thin as i'll go.

Diameter can go down to 136.5 But any farther and you start getting Very close to the basket. and I prefer to not let the tool cut into that.

One thing I have done though is step cut the dia of the weight....
On the back side (toward the motor) I cut 4mm from the width and down to 118mm dia.
and skim cut the basket 1.25mm from the radius at the motor side to 2mm from the outer edge. I did not cut all the way to the edge, due to the timing markings that are stamped there.

That is one of two flywheels im using on my bike
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Old 06-18-2013, 03:35 PM
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Originally Posted by E.Marquez View Post
Some may have noticed the final weights are all over the place...
And they are.

Some of that is due to starting weight. But most of it is the different ways i have reduced weight, where and how far I cut.

When I do the Roger Ditchfield 146 OD, 10.5 wide.... I get a very close final wt between examples. (starting wt and if the part has balancing holes drilled in it effect the final wt... Not all have holes drilled, or the same amount drilled out when they do)

The rest of the differences are accounted for when I turn the OD down, the width down, or both.

This example is 138mm in Dia, 10.5 wide. 6lb 2 1/8oz final wt.

I can take a few more mm off the width, but it makes the lip that locates the sprag clutch a bit thin. 9.5mm wide is as thin as i'll go.

Diameter can go down to 136.5 But any farther and you start getting Very close to the basket. and I prefer to not let the tool cut into that.

One thing I have done though is step cut the dia of the weight....
On the back side (toward the motor) I cut 4mm from the width and down to 118mm dia.
and skim cut the basket 1.25mm from the radius at the motor side to 2mm from the outer edge. I did not cut all the way to the edge, due to the timing markings that are stamped there.

That is one of two flywheels im using on my bike
So the engine revs quicker? Any downside?
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Old 06-18-2013, 03:48 PM
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Originally Posted by jerryh View Post
So the engine revs quicker? Any downside?
The throttle is a little more sensitive (could be considered jerky). The flywheel is basically just a spinning weight so it makes the throttle transitions smoother by slowing them down a little bit. This goes for accelerating and decelerating.

When you snap it open, the bike will open up quicker, as well as engine brake quicker. This is in a way less "tame" and harder on things like the sprockets, if used improperly that is. And arguably less safe in some ways too (snapping the throttle open mid turn for instance), so I'm guessing companies like Honda stay on the side of a little too much weight on the flywheel than too little.

This can all be overcome with a little focus on the throttle control. So if you use it correctly there is no downside. It's quite fun if you like being part of controlling the ride.
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Old 06-18-2013, 05:12 PM
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Not arguing 7mores7's points in general.., but just saying on THIS motor, much of what he points out is not what is noticed by those that have used a lighter flywheel ON THIS bike.

The VTR motor has a ton of rotating crank weight,, dropping 1.2 lb from the flywheel does not exhibit the nasty tendencies outlined by 7more.. but you do get the faster spin up.

I only have 6000 miles on a light flywheel, mostly street, some highway, some faster stuff... and I have not experienced, anything "unsafe" any increased wear on sprocket or chains.
As for snapping the throttle open or closed.... on a stock VTR doing that will unsettle this bike to the point of lost control and likely crash.. not sure how you quantify more then zero control and crash..
Faster crashing with less then zero control
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Old 06-18-2013, 05:43 PM
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I had a '73 R75/5 that I had the flywheel lightened by Reg Pridmore. The starting weight was @ 10.2lbs. The finished weight was @ 5.7lbs. It had @ 102 new holes and looked like Swiss cheese. Operationally, the most notable difference was the quicker response when adjusting the load on the engine, both up and down.
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Old 06-18-2013, 06:38 PM
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Hahaha, I made that sound like a horror story, didn't I! I was just trying to point out why on earth I thought Honda would even make it heavier, unless it was a direct move to reduce horsepower. I did point out that if you're riding correctly there is no downside.

I should have emphasized more that it is a very clean and effective bang for the buck mod, and if I had a new VTR it would be the in the top 5 for mods I'd personally do. Suspension being above it...
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Old 06-19-2013, 05:06 AM
  #39  
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well, I have one of Roger D`s flywheels in my bike, along with (hard anodized and cryogenically treated) aluminum Hyperplate clutch plates, lightened crank and (Carrillo custom) rods (balanced too), not to mention Magnesium wheels, all activated by an HRC 1/6-turn throttle tube.... he he

Not for the ham fisted, but I LOVE it....... response is immediate!!!!!!
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Old 06-19-2013, 10:47 AM
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I'm glad people finally decided that this is a great modification, after years of inglorious debate about destroying your engine with an imperceptible change in the 1X balance, despite the fact that the primary crank load comes from high loads applied by the connecting rods and countered by the primary drive gear...
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Old 11-09-2013, 02:59 AM
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Hi Mr marques I love your work and was wondering how much you charge for this service and post 1 down under
And would you need mine or do you do an exchange thing?
Cheers azza
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Old 11-09-2013, 04:10 AM
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Am I incorrect in my assumption though that part of the flywheels job and why it is as heavy as it is is to ballance the crankshaft as well? Which is also why even though they are all the same engine flywheels differ in weight slightly?
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Old 11-09-2013, 04:33 AM
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Wondered about vibration as well. My husky 610 had been prepped for gncc and had a lightened flywheel. I had steehly add weight for moab trips. Couldn't really feel the difference
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Old 11-09-2013, 06:48 AM
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Originally Posted by aarononafirestorm View Post
Hi Mr marques I love your work and was wondering how much you charge for this service and post 1 down under
And would you need mine or do you do an exchange thing?
Cheers azza
I'll send you a PM.

Thanks
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Old 11-09-2013, 06:54 AM
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Originally Posted by jerryh View Post
Wondered about vibration as well. My husky 610 had been prepped for gncc and had a lightened flywheel. I had steehly add weight for moab trips. Couldn't really feel the difference
No scientific data contained in this post......

In more then 2 dozen flywheels reduced in weight from 10 oz to 1lb 5oz. No issues in REAL use have been found.

I have over 13,000 miles on a lightened flywheel.. most of that in the 6.5k RPM to red line.

Both my son and I ride my SH hard.... I did have another H4 light bulb filament break last week... but that's the only hard part failure I have seen in 38,000 miles.

Lots of folks come up with lots of theory's, math, and unrelated story's about why this will not work... .. yet it works just fine, or has so far, perhaps my crankshaft will bust in two from unrealized harmonics this afternoon..
If it does,,, then i'll change my mind..
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Old 11-09-2013, 06:59 AM
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Originally Posted by insulinboy View Post
Am I incorrect in my assumption though that part of the flywheels job and why it is as heavy as it is is to ballance the crankshaft as well? Which is also why even though they are all the same engine flywheels differ in weight slightly?
In theory, best is.. the entire rotating assembly is balanced as a unit.. In a production bike of low to medium end like the SH,, that's not being done.

The crank shows machining to indicate it is balanced.

The flywheel shows machining to indicate it is balanced as an individual item.
The flywheel is available as individual service item, as is the crank, rods, pistons.

It's the same for every production bike I've ever seen service parts for.

Yes/// we are changing the balance of the flywheel from stock.... No it seems not to cause any issues in actual real life use.
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Old 11-09-2013, 10:13 AM
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Nice work, i'll be sending you mine as well. Just need to get it off first...
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Old 11-09-2013, 10:55 AM
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Originally Posted by jerryh View Post
Wondered about vibration as well. My husky 610 had been prepped for gncc and had a lightened flywheel. I had steehly add weight for moab trips. Couldn't really feel the difference

Jerry, you will not feel the difference on the VTR as well, except the performance improvement, that is very noticeable, the VTR flywheel is very heavy due to the magnets and the amount of cut got almost no effect on the balance, at list from the accounts of many people that did this mod here in the US and in the Europe including myself, mine was cut by E.Marquez to almost maximum you can cut and it is still balanced well with no additional vibrations, the bike is snappier and the engine braking is better as well
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Old 11-09-2013, 04:49 PM
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Originally Posted by E.Marquez View Post
Yes/// we are changing the balance of the flywheel from stock.... No it seems not to cause any issues in actual real life use.
I didn't really think it would, I was more asking out of curiosity, not out of thinking it was a bad thing to do

Anytime you decrease weight you're going to increase vibration at least minimally weather you can tell the difference or not I don't know. I do know though that a lot of guys on the YZF forum (myself included) would put some lead shot in the handlebars to decrease the buzz in them. But thats adding a substantial amount of weight considering how little the part you are adding the weight to is

Last edited by insulinboy; 11-09-2013 at 04:52 PM.
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Old 11-10-2013, 12:04 PM
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I have a lightened flywheel fro H-Power here in Australia.

When I fitted it I also removed the anti rattle gear from the primary drive as well as removed the water pump drive gear and chain at the same time as fitting an electric water pump.


My goal was to reduce mass and now the bike spins up much quicker.




To date after approx 20,000Klms there has been no ill effects other than a saw jaw from smiling too much when I nail the throttle!


Another plus is the improved engine breaking.
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Old 11-10-2013, 06:00 PM
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Originally Posted by kenmoore View Post
I have a lightened flywheel fro H-Power here in Australia.

When I fitted it I also removed the anti rattle gear from the primary drive as well as removed the water pump drive gear and chain at the same time as fitting an electric water pump.


My goal was to reduce mass and now the bike spins up much quicker.




To date after approx 20,000Klms there has been no ill effects other than a saw jaw from smiling too much when I nail the throttle!


Another plus is the improved engine breaking.
Did you weigh all the parts you took out? It would be interesting to know how much rotating mass you lost
Where are you in NSW? I lived in Sydney for several years and would have stayed forever if not my ex...
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Old 11-11-2013, 11:53 AM
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I did weigh the parts however it was a long time ago.

I seem to recall that the difference was approx 2LBs.


It changed the whole character of the engine.


Much more lively and spun up heaps quicker, and engine braking took some time to get used to.


I live on the south coast N.S.W at a place called Cambewarra.


It is near Kangaroo Valley which has some great mountain roads to ride.


Sounds different as well!


I certainly don't regret this mod in any way as it achieved what I wanted which was better throttle response.


Some may find that the throttle response becomes too touchy, but also owning an Aprilia shiver with touchy ride by wire throttle it isn't a problem for me.
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Old 11-12-2013, 10:53 AM
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The Thread Hijack Shiver and stuff thread
https://www.superhawkforum.com/forum...-thread-31362/
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Old 11-12-2013, 11:30 AM
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It would be interesting to put a standard bike and one with a lightened flywheel side by side and do a roll on test to see what happened!

Of course there would be a lot of variables and I wonder if the results would validate the perceived benefits of the flywheel lightening.


Either way I'm not concerned as I enjoy the change in engine character with the different flywheel.


Are there any Dyno charts of before and after for this mod.


Here in Australia for me Dyno time is very expensive at approx $400 a pop.


The closest Dyno to me is 50 miles away and the guys with it are into IL4's in a big way, or Ducati and such!
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Old 11-12-2013, 05:47 PM
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Originally Posted by kenmoore View Post
It would be interesting to put a standard bike and one with a lightened flywheel side by side and do a roll on test to see what happened!

Of course there would be a lot of variables and I wonder if the results would validate the perceived benefits of the flywheel lightening.
I bet it would, I did feel the difference and with your setup, I reckon it is even more so.
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Old 11-12-2013, 07:02 PM
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I also wonder how much the exhaust sounds vary when flywheels are altered by differing amounts.

I must admit that mine sounds different to what it did, the V effect is not as pronounced which to me is the only downside!


It still sounds like a V but not as syncopated, could be my imagination but my friends say the same.(Yes hard to believe that I have friends)


Too many mods ago to remember what it sounded like in its original strangled form, however I heard a standard bike with Staintunes the other day and it sounded rougher and lazier.
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Old 11-12-2013, 08:31 PM
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Originally Posted by kenmoore View Post
I also wonder how much the exhaust sounds vary when flywheels are altered by differing amounts.

I must admit that mine sounds different to what it did, the V effect is not as pronounced which to me is the only downside!


It still sounds like a V but not as syncopated, could be my imagination but my friends say the same.(Yes hard to believe that I have friends)


Too many mods ago to remember what it sounded like in its original strangled form, however I heard a standard bike with Staintunes the other day and it sounded rougher and lazier.
No exhaust note change that I have noted on my bike, or those I have installed a lightened flywheel on.
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Old 11-12-2013, 08:35 PM
  #58  
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Kenmore, so your sayin' that with all that weight taken off the rotating assembly, it became such a smooth engine, that it's hard to tell that it's a V-Twin?

Edit: Err, wait...was that a Shiver engine that you removed the rotating mass from? If so, I will remove my post and post in the other thread which was created. Way to create confusion Erik. I'll just blame it all on you haha

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Old 11-12-2013, 09:49 PM
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Originally Posted by CruxGNZ View Post
Kenmore, so your sayin' that with all that weight taken off the rotating assembly, it became such a smooth engine, that it's hard to tell that it's a V-Twin?

Edit: Err, wait...was that a Shiver engine that you removed the rotating mass from? If so, I will remove my post and post in the other thread which was created. Way to create confusion Erik. I'll just blame it all on you haha
Hey now... It's Kenmoore like Ken Moore, not Kenmore like the kitchen appliances
Reducing the flywheel or other rotating mass from the engine have nothing to do with the exhaust sound, except the rate of acceleration.
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Old 11-12-2013, 10:01 PM
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Originally Posted by NHSH View Post
Hey now... It's Kenmoore like Ken Moore, not Kenmore like the kitchen appliances
Reducing the flywheel or other rotating mass from the engine have nothing to do with the exhaust sound, except the rate of acceleration.
Haha, oops. Sorry Kenmoore.

I wasn't saying that the exhaust note itself changed, just the frequency...or, heck, I can't explain it. I've had a couple cocktails and my brain has dyslexia and my mouth has verbal diarrhea. I shall step back behind the keyboard and simply watch instead
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