lightened flywheel?

[88vmx12]

Has anyone on the forum lightened their Vmax flywheel? If so what do you think about it... Pro or Con...

Thanks Scooter

 

[maleko89]

I have one for my early model. It weighs the same as the late model flywheel now. I didn't notice much difference at all and think you'll lose a bit of torque down low.

 

[satariel666]

Mark i second that.

Plus it will couse more vibration from engine.

 

[88vmx12]

I hate to say this but I tend to disagree. If you take weight from a balanced flywheel whithout changing the balance. The harmonics should not change. I can see that torque can be lost because mass has been removed from the flywheel. The main thing noticed should be how quick the throttle responce is. It should be noticably quicker..

Scooter

 

[satariel666]

I hate to say this but I tend to disagree. If you take weight from a balanced flywheel whithout changing the balance. The harmonics should not change. I can see that torque can be lost because mass has been removed from the flywheel. The main thing noticed should be how quick the throttle responce is. It should be noticably quicker..

Scooter

They should be the same but practicly they not. Most people do not balancing flywheels after lightweighting.

Imo its the worst tupne up you can do in engine.

Lets start form the question: whats the flywheel do?

IMO flywheel corrects torque fluctuations by specificly calculated mass.
It could not be to light or to heavy.
Flywheel weight is calculated at factory when engine is examinated at CRANKSHAFT DYNOMETER. Engine developers always try to match that weight for the torque to become balanced at all rpm range.

There more rpm there less torque fluctuations and there more flywheel weight then less vibrations you have and more torque.

Lightweighting gives you more max rpm so teoreticly more power and definitly better respone and midrange but worse response at rpm close to idle, why?
Flywheel create a mass with crankshaft and that mass stands against rod and piston when piston is going to the BDC at combustion cycle.
So less weight=less power to countertact that force.

Its only happening at engine low speeds.

So i must disagree with you.

Its good mod for race use but not good for street use couse it will couse vibrations and it will shortening engine life.

PS
I hope that you will understand what im trying to say.
Im not the handiest guy with the TECHNICAL english.

 

[88vmx12]

satariel666,

I understand where you are comming from, on the vibration issue of the engine. I have spoken to a few motorcycle engine builders. Not one of them has come up with that except on a V twin. Where the engine is not in total balance and that is why they add weight to a flywheel.. I have one other guy to ask that knows the Vmax engine inside and out ( that is what they say ). I am not trying to tick you off in any way shape of form. I am only sitting here scratching my head trying to figure out what is the differance between an auto engine than a bike engine. I have done some lightening on some flywheels on some engines and some balancing of the engines too. They were far from race engines. They were all daily drivers.... So that is why I understand what you are saying , but still confused because of my previouse experiences...

Scooter

 

[hubeerjw]

I kept the Venture 1300 flywheel (which is even heavier than the heaviest Vmax flywheel) in my drag bike to help with the torque. I know it will hurt the speed of the engine to rev, but I think it is more beneficial to have the additional spinning weight/torque for launches. I don't know if any of this is true or not, but I know that old school drag racers added weight to the flywheel to have that additional inertia for launches. Maybe that is an old way of thinking and has been proved or disproven... I guess I'd like to know the answer myself.

 

[4gasem]

I think your turbo over comes that drag! lol

 

[88vmx12]

I kept the Venture 1300 flywheel (which is even heavier than the heaviest Vmax flywheel) in my drag bike to help with the torque. I know it will hurt the speed of the engine to rev, but I think it is more beneficial to have the additional spinning weight/torque for launches. I don't know if any of this is true or not, but I know that old school drag racers added weight to the flywheel to have that additional inertia for launches. Maybe that is an old way of thinking and has been proved or disproven... I guess I'd like to know the answer myself.

I agree you need the weight to keep the inertia going when you have a sudden lugging like from a launch off the line. My uncle claims that his montesa trials bike has a 25# flywheel. I have ridden it in the mountains. Crazy bike to ride, up and over rocks with hardly any throttle. I also had a 1994 Toyota pickup with a 22RE 4 cylinder engine. I ordered a heavier flywheel. It was awesome on the hiway on rolling hills. It had hardly any power and the heavier flywheel helped a ton...

But I have ran across two companies that sell lightened flywheels. I know that at the bare minimum 50% of the people on this site . That have purchased aftermarket / custom parts have purchased from them. I don't feel that they would sell a product that would harm the engine. They have too good of a reputation.

Scooter

 

[satariel666]

satariel666,

I understand where you are comming from, on the vibration issue of the engine. I have spoken to a few motorcycle engine builders. Not one of them has come up with that except on a V twin. Where the engine is not in total balance and that is why they add weight to a flywheel.. I have one other guy to ask that knows the Vmax engine inside and out ( that is what they say ). I am not trying to tick you off in any way shape of form. I am only sitting here scratching my head trying to figure out what is the differance between an auto engine than a bike engine. I have done some lightening on some flywheels on some engines and some balancing of the engines too. They were far from race engines. They were all daily drivers.... So that is why I understand what you are saying , but still confused because of my previouse experiences...

Scooter

No any hard feelings, just a loose discusion


My theories coms from experiences with lightweighting the flywhees.
I've lightened flywheels in boxer engines and it was a bad decision.
Boxer is a very specific engine and cant run without flywheel couse it will rip it into pieces.
Once i've lightened boxer flywheel to much and get spun crank bearing :confused2:
I've also lightened couple of flywheels in other engines and always get more vibrations as a result. Ya know, not a big ones that shake the engine, only
slighty ones but sensible.

But never done this on v-max so i cant be an expert here.

Just my toughts

 

[satariel666]

I agree you need the weight to keep the inertia going when you have a sudden lugging like from a launch off the line. My uncle claims that his montesa trials bike has a 25# flywheel. I have ridden it in the mountains. Crazy bike to ride, up and over rocks with hardly any throttle. I also had a 1994 Toyota pickup with a 22RE 4 cylinder engine. I ordered a heavier flywheel. It was awesome on the hiway on rolling hills. It had hardly any power and the heavier flywheel helped a ton...

But I have ran across two companies that sell lightened flywheels. I know that at the bare minimum 50% of the people on this site . That have purchased aftermarket / custom parts have purchased from them. I don't feel that they would sell a product that would harm the engine. They have too good of a reputation.

Scooter

Im sure they dont. They know how much can be taken from flywheel.
They are pros.

You will feel the diffrence after many miles or maybe never. Its depends
how much you will lightweighted your flywheel.

Thats my theory, im not a pro and i can be wrong.

 

[kaboom]

The flywheel is used to smooth out engine power output between the firing of the individual cylinders.....

On a multi cylinder engine with an even and sequential firing order the flywheel can weigh less due to the inherent balance and more linear power output....

In an odd-fire multi cylinder(Harley) or a large single cylinder you need added flywheel mass to smooth out the power curve.....

The Vmax.....I believe....Is an odd-fire 720 degree V4......and needs heavy flywheel balancing....


Otherwise you will FEEL every power pulse from the engine and the gap between them at low RPMs....
It would be a very jerky and unsteady power delivery...

As RPMs rise the gaps become less noticeable and power delivery appears to smooth out.....so the flywheel effect is diminished.....

Make sense???

 

[satariel666]

The flywheel is used to smooth out engine power output between the firing of the individual cylinders.....

On a multi cylinder engine with an even and sequential firing order the flywheel can weigh less due to the inherent balance and more linear power output....

In an odd-fire multi cylinder(Harley) or a large single cylinder you need added flywheel mass to smooth out the power curve.....

The Vmax.....I believe....Is an odd-fire 720 degree V4......and needs heavy flywheel balancing....


Otherwise you will FEEL every power pulse from the engine and the gap between them at low RPMs....
It would be a very jerky and unsteady power delivery...

As RPMs rise the gaps become less noticeable and power delivery appears to smooth out.....so the flywheel effect is diminished.....

Make sense???

:thumbs up::thumbs up::thumbs up:

 

[RMSVMAX]

OK, I'll bite on this one...LOL

We lighten flywheels to help a VMAX motor rev quicker.
The stock early wheels are about 9.5 lbs. or so, and we lighten them to about 5.5 or 6...(been a while since I weighed one...)
The late model (90up) are about 7.5lbs. or so,
so YAM must have figured the revs need help, over an abundance of torque...
We sell more early wheels, because the weight loss is much more significant, and makes more diff...
There is still suite a bit of flywheel 'effect', both from the lightened flywheel,
and the rest of the rotating engine internals, INCLUDING the balancer shaft, so it's not a drastic diff, and does not affect any streetability.
It just gets trimmed down a bit, and Yes, you can hear a bit more of the lumpiness from the cams, but that's NOT a bad thing, and it's still very driveable.
I like the quicker revs, particularly in a blow or big-bore MAX, but even in a 85-89 1200, it is nice to get the quicker revs.

Hope this helps;
Thanx for asking!

John
RMSportMax:eusa_dance:

 

[satariel666]

Now we have a pro opinion.
Intrestiong.

But what about guys with venture dif and streetability? :ummm:

 

[88vmx12]

No any hard feelings, just a loose discusion


My theories coms from experiences with lightweighting the flywhees.
I've lightened flywheels in boxer engines and it was a bad decision.
Boxer is a very specific engine and cant run without flywheel couse it will rip it into pieces.
Once i've lightened boxer flywheel to much and get spun crank bearing :confused2:
I've also lightened couple of flywheels in other engines and always get more vibrations as a result. Ya know, not a big ones that shake the engine, only
slighty ones but sensible.

But never done this on v-max so i cant be an expert here.

Just my toughts

Hey I understand where you are comming from. Messing with an engine is a risky and sometime costly. In your experiences it has been a bad decision in mine there has been no bad outcome. So I guess we are both sitting on the fence until we get imput from a so called expert ( AKA drip under pressure )

Your imput is always welcomed! Scooter

 

[88vmx12]

John,

Nothing intended by the Expert ( AKA drip under pressure ) LOL . Your imput is well worth it. You have messed with alot of Vmax alterations and know the pro's and con's.
I just spoke with you the otherday on doing a one off drive shaft for a ZL900...

Thanks again

Scooter

 

[88vmx12]

Ok guys.

Nothing against you John. I was trying to see if this lightened flywheel thing was what I wanted. To everyone ,I don't want my decision to hinder John's sales. So what I have chosen is not layed in stone! I was actually able to speak to a guy that knows the Vmax engine inside and out. They used the Vmax power plant to set a land speed record in a special set up car. The conversation was very interesting and well worth the call. It was almost talking to a Vmax God. It was very cool , he was looking at the parts break downs as we spoke. Asking many questions IE. plans for the bike, what I was going to use it for .... How the bike was set up Etc. He actually works at a Yamaha dealer as a shop foreman , which I think also gives him an upper hand on his land speed record car. By our conversation I decided that it was not what I wanted to do. It had nothing to do with harmonics or balancing of the engine. So what John sells , there is nothing wrong with his product, I have just chosen not to go that route. Because it just not what I am after....

Thanks Scooter

 

[one2dmax]

I recommend the heavier flywheels for dragracers. Stock flywheels are fine for most guys and in my opinion are not worth the effort required to do the change. Lighter will allow for quicker revs and quicker response but will have more vibrations as noted.

We have also run/built engines with machined down lobes on the counter balancer shaft and 4-5k vibrations are much increased. We've even built drag motors with balance shaft amost completely removed (just the end where the pump hooks too) and my alcohol drag bike doesn't even have one at all.

To each thier own. I don't want to say there is a down side and for that little bit more response you may find it worth it.

Sean

 

[Rhoy Carter]

I had to run a lightened flywheel on a 1975 750 honda (punched out to 1080 with a 1/4" longer stroke crank "1162 cc"). I rode this bike on the street and took it to the drag strip. The reason I had to lighten the flywheel was because the crank would twist right behind the flywheel ( this was before I stroked it). At the strip with a roadrace slick and wheelies bars the best time was 10.64 at 133 mph (that was with a 145 pound rider.
I still miss that 750 it was a total sleeper. My 85 Vmax is close to it on the street and a lot cheaper to keep running.