aluminum vs lightened flywheels?

[danaid]

It could be a matter of perspective.
The nichols flywheel and high comp pistons made a huge difference in both throttle response and engine braking on my 750.
 I liked the new found life it gave the old gal.
 But it also made it very touchy in stop and go traffic.(aka: downside)
Wrist control is an art form in it's own right.

 Did you notice any new engine vibrations with the lightened flywheel?

 

[BK_856er]

I have a nichols aluminum flywheel in my M695.  I think it's a little over a year old at this point with about 6k miles on it.  No problems at all.  I would not go back to the stock flywheel, but as mentioned the nichols requires a finer touch on the throttle and the engine braking feel is a bit different.  There might be some more vibes, but nothing irritating or mirror-blurring.  I have no issue with around town riding.  I had it out recently to do some shift linkage work and the flywheel splines looked absolutely perfect.  Just a datapoint...

BK

[koko64]

My steel flywheel had about a kilo machined off. It's about 900 grams now. I think that is a good compromise.

I have had a DP alloy flywheel on another 900 2 valver, and it was quite a bit lighter. The bikes had the same mods, FCRs, hi comp pistons, dialed cams, Vee Two light clutches, open A/B. The lighter flywheel was more snatchy down low and caused more engine braking than I liked.

The machined flywheel feels about just right to me. It's a matter of personal taste, however.

[brad black]

the flywheel impacts inertia of the crank assembly.  inertia is mass time radius squared.

the dp aluminium flywheel looked like a std one, but was al and about 1/3 of the weight, so had 1/3 of the inertia.  we had a couple of them lose their splines years ago, so we stopped using them.  this was about the time the torque on the rotor nut went up from 180 to 270nm, which could have been a contributing issue.

a steel one on a fuel injected bike goes down from 148mm to 120mm od when i do them, and the weight from 1900 to 875 grams.  combined i guess the reduction in inertia is .46  x .81 x .81 = .3 in very round numbers.  so about the same.

the carb bikes have the lump for the pick ups on the od, so you can't just take them down like a injected bike one.  i took my 750m one down form 1900 to 1400 grams from memory being cautious.  i did have a pre 98 600 flywheel on it previously to refitting the lightened 750 one as i'd played with the pick up trigger lump in conjunction with the ignitech.  the 600 flywheel is a stamped steel dish weighing about 650 grams.  went great, no low speed issues at all.  just went harder and lifted the front wheel faster was about all i noticed.

my 851 has an old dp one for the p7/p8 ecu, it's al with a steel ring bolted to the outer edge with 4 lumps on it, just like the dp ones for single phase alt 2v carb motors.  it's about 690 grams, which is a bit of a theme.

ime the injected bikes are a touch smoother with the flywheel machined.  no idea why, but it's a common feeling from me and customers.  it does exagerate poor low speed tuning, which in turn can make them unpleasant to ride.  std crank weights 4.5kg, sp/r style crank 4kg.  plus the alt rotor, starter clutch carrier, primary gear.  there's still a lot of weight there.

but look at an 848 crank and flywheel and you'll see how far the factory has gone in reducing the weight.  personally it's one of the mods i'd make to anything after doing the cam timing.

[TAftonomos]

I've had the cheapo SSR aftermarket aluminum flywheel on the last dozen ducati's I've had.  Made sure the threads were clean, seated the thing properly, used loctite and the double nuts that come with it, and torqued to spec.

Never had an issue that people claim the splines shear off the thing.

Never thought....man, I shouldn't have done that the bike is terrible.  Always a positive mod, and one of the first to be done after setting up the forks/shock for my weight.

[BlackKat]

Looks like I'm leaning towards the lightened stock flywheel. Does anyone know if there are any suppliers that offer them in their stock or have a core on yours to cut down on the down time of waiting for my flywheel to get turned down? We use Ben Fox. He does amazing work, but he's always really busy and Spring is creeping up on us in Ohio fast!

[ducpainter]

Looks like I'm leaning towards the lightened stock flywheel. Does anyone know if there are any suppliers that offer them in their stock or have a core on yours to cut down on the down time of waiting for my flywheel to get turned down? We use Ben Fox. He does amazing work, but he's always really busy and Spring is creeping up on us in Ohio fast!

Try eric@clubhousemotorsports.com 603-393-8945.

He had an assortment of lightened stockers hanging on the board ready to go earlier this winter, and he's a sponsor.

[BlackKat]

Dropped him a line-Thanks!

[koko64]

I reckon that's they way to go as far as bang for buck is concerned.
Given my comments, I'm still curious to try a very light Nichols flywheel. They are very light.
The light DP flywheel on my Superlight had me hopping the rear into corners and wanting a slipper clutch. I found this effect was reduced with a light clutch (basket, hub/drum and plates). There was a relationship there.

[BlackKat]

Well, I emailed Eric on Sunday and never heard back. A DMF member emailed me and had one (lightened stock) at a great price, so I hope to do a nice before and after review on an otherwise bone stock s2r1000. The FBF pistons are in route and I'm considering the lightened adjustable timing pulleys...

well see if I can make a peppy retro cafe bike outa this one....

[Goduc]

A lightened stock flywheel would have given you the same response, without the around town issues you ran into. 

  Not possible.  The difference made is due to the reduction in rotating mass, If the stock machined flywheel weighed the same as a Nichols, for instance, they would behave exactly the same.  In fact, the only way they would have the same characteristics is if they weighed the same.  As for the engine braking I had a hard time noticing it, I had a Corsa Racing Slipper clutch installed in mine the same time as the lightweight flywheel.  I love the combo!

[kopfjäger]

  Not possible.  The difference made is due to the reduction in rotating mass, If the stock machined flywheel weighed the same as a Nichols, for instance, they would behave exactly the same.  In fact, the only way they would have the same characteristics is if they weighed the same.  As for the engine braking I had a hard time noticing it, I had a Corsa Racing Slipper clutch installed in mine the same time as the lightweight flywheel.  I love the combo!

The nichols or other super lightweight flywheels are for race applications not the street.

[Raux]

  Not possible.  The difference made is due to the reduction in rotating mass, If the stock machined flywheel weighed the same as a Nichols, for instance, they would behave exactly the same.  In fact, the only way they would have the same characteristics is if they weighed the same.  As for the engine braking I had a hard time noticing it, I had a Corsa Racing Slipper clutch installed in mine the same time as the lightweight flywheel.  I love the combo!

pure physics, it's not just the weight, but the distribution of that weight on a rotating part.

so say a steel flywheel has been reduce in diameter to be lighter vs a full size aluminum that is lighter than stock but the same as said reduce diameter steel... they would have different characteristics

[Goduc]

The nichols or other super lightweight flywheels are for race applications not the street.

Well, I have been using it in a street application for about 8,000 miles and its worked great the whole time...

[Goduc]

pure physics, it's not just the weight, but the distribution of that weight on a rotating part.

so say a steel flywheel has been reduce in diameter to be lighter vs a full size aluminum that is lighter than stock but the same as said reduce diameter steel... they would have different characteristics

True, but I was assuming that much.  Too much to assume apparently.