Lightned Flywheel Opinions

[killerniceguy]

I have been contemplating installing a Nichols Flywheel on the bike this winter.  Loosing almost 3.5lbs of rotational mass seems quite appealing but what are the advantages/disadvantages of doing this?  Here is what I know so far:

Pros:
Less rotational mass
Much faster rpm gain
Much stronger engine braking

Cons:
Less forgiving with throttle inputs - you must be smooth

Any additions/opinions  are appreciated.

KNG
S2R800

[Raux]

if i remember right the rotational mass of the flywheel also affect the 'flickability' of the bike. less mass, less willing to stay upright so easier to throw into a lean. but wouldn't that affect the bike wanted to stand back up as well?

[He Man]

less engine braking. less mass for the rear wheel to spin.

[Capo]

if i remember right the rotational mass of the flywheel also affect the 'flickability' of the bike. less mass, less willing to stay upright so easier to throw into a lean. but wouldn't that affect the bike wanted to stand back up as well?

The gyroscopic force of the rotating mass resists changes to it's axis. Once overcome the mass assumes a new axis. Both sides of a "flick" (up and down) are affected by the rotating mass.

[Spidey]

less engine braking. less mass for the rear wheel to spin.

Actually, more engine braking.  The engine spins up faster.  But it also spins down faster when you let off the throttle b/c less rotating mass.  When the engine spins down more quickly, there is more engine braking.  You might be refering to wheel hop.  There is less wheel hop from a hard downshift because the engine will spin up quicker to match the wheel speed.  It actls like a poor man's slipper clutch.

Con:  possible stalling at low rpm. 

[Wanwo]

I installed one and a week later went back to stock.

The first problem I had was the bike became a lot easier to stall. I had to learn to give it extra revs when taking off or the engine would just putt out. Secondly, it increased vibration. I know this for sure because when I went top speed down the freeway the numbers on my speedo would be blurring to me, something I'd never seen before. And finally I really didn't feel it brought much of any benefit at all. I'm sure if I was a higher end rider it would, or if I rode on a track, but I'm not that. Mostly do city stuff so ease of use and comfort are more important than outright performance. And it's not like I need more performance. I still got a long way to go to catch up to the limits of what this bike can do.

Anyway, for what it's worth that's my experience.

[DucSteve]

I'm interested in this mod myself... any other opinions/reviews?

[Capo]

I have the DP one on my S4R, it certainly spins up quicker and I have not noticed any low speed problems. However most of my riding is done at speed on back roads little or no 'traffic'.
If you use your monster for 'sport' riding then a light weight flywheel might be beneficial, if your riding involves a large amount of city commuting then stay with the stock item.

[He Man]

Actually, more engine braking.  The engine spins up faster.  But it also spins down faster when you let off the throttle b/c less rotating mass.  When the engine spins down more quickly, there is more engine braking.  You might be refering to wheel hop.  There is less wheel hop from a hard downshift because the engine will spin up quicker to match the wheel speed.  It actls like a poor man's slipper clutch.

Con:  possible stalling at low rpm. 

Ahh! that makes sense! Thanks for clearing that up

[greenmonster]

Actually, more engine braking. When the engine spins down more quickly, there is more engine braking.

Is that really so?
The mass that is forced to accelerate or decelerate is less, therefore the breaking is less w a lighter fwheel. W a heavy one you clearly feel more
weight has to be altered, especially in city traffic in 2nd-3rd gear were a lighter fw is surely smoother.
The engine surely revs faster up & down, BUT, is that really more engine breaking?

I don`t know the facts about this, just referring what it feels like to me.

[MaxPower]

Is that really so?
The mass that is forced to accelerate or decelerate is less, therefore the breaking is less w a lighter fwheel. W a heavy one you clearly feel more
weight has to be altered, especially in city traffic in 2nd-3rd gear were a lighter fw is surely smoother.
The engine surely revs faster up & down, BUT, is that really more engine breaking?

I don`t know the facts about this, just referring what it feels like to me.

Yeah, it is so.

When you say "mass that is forced to accelerate or decelerate is less..." it sounds like you have it kind of backwards on the decel side of things.  When you cut the throttle, it's the mass, or rather the inertia of that mass that controls the deceleration. 

The important thing to remember is if you cut the throttle, the engine wants to go slow but the inertia of the bike (flywheel in this case) forces it to keep going at a higher rate (For example, cut the throttle in neutral, it goes to idle speed.)  So the engine fights the bikes inertia, slowly slowing the bike down to the speed the engine wants to be at.

So, if you use a lighter flywheel, there is less inertia for the engine to fight.  It's easier for the engine to get to the revs it wants to be at i.e. it happens faster.  More engine braking.

[S2daRk]

Is that really so?
The mass that is forced to accelerate or decelerate is less, therefore the breaking is less w a lighter fwheel. W a heavy one you clearly feel more
weight has to be altered, especially in city traffic in 2nd-3rd gear were a lighter fw is surely smoother.
The engine surely revs faster up & down, BUT, is that really more engine breaking?

I don`t know the facts about this, just referring what it feels like to me.

I guess it depends on how you define engine braking. Since the engine spools up faster when you're on the throttle, some people view that as "less engine braking." Conversely, since the engine spools down faster when you're off the throttle, some people view that as "more engine braking." I prefer to view it as the latter, because I tend associate the term "braking" when you're OFF the throttle and slowing down.

As for my opinion, I have an 800 motor and I welcome the improved throttle response. If I had a more powerful motor (S4R), I would probably leave it alone. With a lighter one, you definitely have to be smoother when getting on and off throttle (I immediately noticed that the first time I lane split after installing the lighter flywheel).

Also, the Nichols flywheel is MUCH lighter than the stocker. I went with an MPL unit, it's a good compromise between the heavy stocker and the superlight Nichols.

[Duck-Stew]

Con:  possible stalling at low rpm. 

Ya think?!?  Hehehe...

Had one in my M750i.e. CR and it was too light for the mass of the crankshaft and my *personal* tastes.  When I rode over a bump, the weight of my body shifting about caused an almost inperceptable change in the throttle.  Well, the engine responded to it and the bike lurched forward and needed to be kept in check.  So, for me, my tastes and my bike...  (translation: YMMV) the solution was a stock flywheel with some mass cut off of the perimeter.  $20 on Ebay for the flywheel, and another $25 at the machine shop to chuck it up and turn it down.  Result?!?  Perfect for me, and my bike!

[Spidey]

There's an easy solution for low rpm stalling.  Avoid low rpm.  At all costs. 

[Duck-Stew]

There's an easy solution for low rpm stalling.  Avoid low rpm.  At all costs. 

Yeah, there's that...