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What's the Flywheel for? (Read 583 times)
Dave
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Re: What's the Flywheel for?
Reply #30 - 06/18/20 at 17:54:29
 
Next time I have a Savage apart, I will weight the rotating parts.

There is a huge amount of mass in the crankshaft, the electrical rotor and the balancer.  The flywheel on the Savage does add some momentum - but for the majority of us it has proven not to be necessary......and the bike accelerates a bit quicker with less flywheel mass.
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DragBikeMike
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Re: What's the Flywheel for?
Reply #31 - 04/09/21 at 13:16:23
 
I stumbled across this interesting YouTube vid and thought it would add a little perspective to this old post.  The Russian adds a whole bunch more flywheel to his little car.  It behaves as you would expect.  His observation regarding clutch engagement and how the additional flywheel would be beneficial to a student driver seems germane since the Savage is billed as a beginner bike.

Crazy project.  I love his stone-axe approach.  Just go for it.  Great that he increased the mass in steps by adding additional flywheels one at a time.  Wish he had some snow-free roads to do the test.

https://www.youtube.com/watch?v=0M92bfoJZMo
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Re: What's the Flywheel for?
Reply #32 - 04/09/21 at 17:25:06
 
We used to swap out aluminum clutch plates for steel plates in mx bikes if we wanted to smooth out the delivery and increase traction.  It was more prevalent in the off-road disciplines like enduro and hare scrambles.
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« Last Edit: 04/10/21 at 05:15:34 by ohiomoto »  
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Re: What's the Flywheel for?
Reply #33 - 04/10/21 at 03:52:56
 
He adds the third flywheel and proclaims - "The bolts are too long no more!"

I have watched several of videos from this guy......including the one where he made a wooden crankshaft.  He is not afraid of spending a lot of time on creative projects that are likely to have unhappy endings.

Back in the early days of gasoline engines - if was not uncommon for opera houses and similar buildings to have their own generating plant.  The Cit of Walton where I was City Engineer used to have an engine and dynamo and they made the electricity for the town.  These single cylinder engines would be modified over the standard engines by having larger/heavier flywheels - so that the engine rpm would stay more even over the compression/exhaust stroke.....and these engines were throttle governed rather than being the hit/miss type of engine.  If the rpm varied the electric voltage would change.....and the lights would get brighter/dimmer as the rpm varied.

Big flywheels are great for things like tractors, generators, trains, ships and any use where you want a steady output of power and a constant speed - light flywheels are best when you want to vary your speed rapidly.  Road driven cars and motorcycles are a compromise as you do want steady speeds at times - but you also want the ability to accelerate.

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Re: What's the Flywheel for?
Reply #34 - 04/10/21 at 13:13:37
 
I'm curious what effect it has on top speed.  Our big single-cylinder engine has a long interval between power strokes.  We get 180 degrees of push and then have to wait another 540 degrees before another push occurs.  Of that 540 degrees, 180 degrees is used to compress the fresh charge.  Seems to me that the stock flywheel might help store some energy that can be used to barge through the wind until the next power stroke occurs.  Note that the Russian said the engine didn't want to slow down.

Multi-cylinder engines have smaller pushes spaced closer together.  Two-stroke singles get a push every 360 degrees.

I have a self-imposed prohibition on LSRs.  After my WOT fry job on the old tight-quench motor, I decided that top speed attempts would no longer be prudent.  But for quite some time now I have pondered that flywheel.  I'm confident that the 3-inch flywheel improves my rate of acceleration, but I have this suspicion that the BIG flywheel might be beneficial for a LSR attempt.  I plan to do some tests on the acceleration aspect but  I'll leave the LSR stuff to the guys who live in Nevada.

A phenomenal amount of energy can be stored in a rotating mass.  Big heavy flywheels can be dangerous.  There's just no stoppin them.

Ohio, were those dirt bikes with the aluminum clutch plates Huskys?
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Re: What's the Flywheel for?
Reply #35 - 04/12/21 at 04:34:14
 
No.  All the Japanese 125s and 250s used aluminum plates. There were a few Honda 250s in the late 80s and 90s the hit particularly hard so some guys were using steel plates.  I tried it and it made a small but noticeable change.  
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Re: What's the Flywheel for?
Reply #36 - 04/20/21 at 20:20:00
 
I guess this lightening of flywheels is to get more acceleration
Some Dr 650 guys drill bigger breather holes in the bottom of their flat slides and cut a few tiurns off the diaghram spring to lessen the preload to
get quicker throttle response
Has anyone tried this on our savage?
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Re: What's the Flywheel for?
Reply #37 - 04/20/21 at 22:38:10
 
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Re: What's the Flywheel for?
Reply #38 - 05/06/21 at 16:13:07
 
Its still this.. the flywheel is only a (1) part for storage of energy frome the combustion, to make the enging going 720 degres.. IE one whole cycle.

Its still a thumper, and there are heavyer parts to, like the crankshaft, and the balance axell, and to that even the generator.

And its still to make the engin to work even att low/medium revs.

There are both pros and cons of this.. perticulary this this engin only have one cylinder.

Pros is that ir uns even at low and middle revs.. its usable for moste people.

Cons is, there is a lot of inertia to make it turn 720 degres to get a new combustion. That makes the engin not that fast to react on the gas handel, whit the clutch not engaged.. there is a delay for shifting gear.
Thats not a problem.. one get used to ones bike and how to shift gear.

To that, whit clutch engaged and any gear in postion, then it shifts to the inertia of the whole bike + the rider.

Soo, one can get rid of the flywheel, the balance axcel and the generator, only use highest ever tollerable revs.. then its become a dragbike, its stupid.. but one can probably get some better accelration out of it.. if its used as a drag bike.
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Re: What's the Flywheel for?
Reply #39 - 05/07/21 at 02:31:23
 
Zepp wrote on 05/06/21 at 16:13:07:
There are both pros and cons of this.. perticulary this this engin only have one cylinder.


Zepp:  As you stated in your post, there is a lot of rotating mass in the Savage.  The crankshaft is heavy, the balance shaft is heavy and spins at twice the engine speed, and the electrical rotor is heavy......as is the flywheel.

I installed a mid-weight flywheel initially, and then later I installed a super light flywheel - and I really have not noticed any "cons" to the switch.  The "pros" are that I did cut my 0-60 time by 1/2 second with the mid weight flywheel as measured by my GPS speedometer.....I have not done a timed run with the super light one yet.  The bike idles the same, starts just as easy, cruises the same - it appears that all the other spinning parts have plenty of rotating mass to keep the engine happy.

Speculation doesn't always prove to be accurate - thankfully DragBikeMike documented his experience.....and Armen made us some light pulleys for those of us who cannot build our own.  The folks who have installed them all believe they work great! Smiley  
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Re: What's the Flywheel for?
Reply #40 - 05/07/21 at 11:22:11
 
My current project involves a bunch of incremental tests starting from a box-stock engine.  The flywheel mod will be included.  Hopefully I can add some useful data on the flywheel.  I'm very curious how the timed runs will stack up with my old seat-o-da-pants evaluation.  One thing that has baffled me from the git go is the "rap in neutral".  It simply doesn't seem to rap any faster with the small flywheel.  I've reduced rotating mass on a number of different engines.  They always rapped faster in neutral, behaved exactly like the Russian's Lada.  The Savage did not respond like that.  Nothing beats collecting hard data.
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Re: What's the Flywheel for?
Reply #41 - 05/07/21 at 12:31:05
 
Rap?
Rev?
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Re: What's the Flywheel for?
Reply #42 - 05/07/21 at 16:39:00
 
Dave wrote on 05/07/21 at 02:31:23:
Zepp wrote on 05/06/21 at 16:13:07:
There are both pros and cons of this.. perticulary this this engin only have one cylinder.


Zepp:  As you stated in your post, there is a lot of rotating mass in the Savage.  The crankshaft is heavy, the balance shaft is heavy and spins at twice the engine speed, and the electrical rotor is heavy......as is the flywheel.

I installed a mid-weight flywheel initially, and then later I installed a super light flywheel - and I really have not noticed any "cons" to the switch.  The "pros" are that I did cut my 0-60 time by 1/2 second with the mid weight flywheel as measured by my GPS speedometer.....I have not done a timed run with the super light one yet.  The bike idles the same, starts just as easy, cruises the same - it appears that all the other spinning parts have plenty of rotating mass to keep the engine happy.

Speculation doesn't always prove to be accurate - thankfully DragBikeMike documented his experience.....and Armen made us some light pulleys for those of us who cannot build our own.  The folks who have installed them all believe they work great! Smiley  


Thanks, I dont disagre that much frome your opinion!
There is a lot of spining mass in our engin.
And mayby some Suzuki enginers put on a to heavy flywheel, to make it work for non experiancde drivers?

In anyway.. it still dont affect the inertia of the bike+driver that much.
Whats afect the inertia of a wehicel is weigt of both wehicel and driver.

And there is more to that.. one other importante thing how much clutch engagement time.

To that.. the engin need clutch to be to deliver power for forward drive/acceleration.. its basic mecanical/fysic understanding.

Then to next understanding.. to shift gear.. preferably the input and the outpout shaft should have similar turning rates.. its becuse of that we use the gas handel to eighter lower or rise the engin speed!

Any experianced rider dont ever think of this.. the juste do it.. by experiance!

And then to acceleration.. its about full clutch engagement on full gas handel!

Its easy to this on first gear.. then come some minor problems.. one need to shift to another gear.. and later to another.. it take seconds with no clutch engaged and gas handel lower to engage any next gear!

Summarise.. inertia/weight of moving parts of our engin dont do affect that much acelleration except clutch engage/full gas time.

In another solution, get rid of any helmets and other heavy biking clothings and one can probably get som better speed records.. dont do this at home.. its only stupid and dangerus!

I think I alredy sumarised.. but in case, dont drive naked on a bike, and dont even think about that a lighter flyweel gonna afect accelration on any bike.. except clutch time on a racing track. Smiley
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Re: What's the Flywheel for?
Reply #43 - 05/07/21 at 17:53:42
 
[quote author=59667373030 link=1529391534/30#42 date=1620430740][quote author=1D262B3C2D213A3C272F223D4E0 link=1529391534/30#39 date=1620379883]Zepp wrote on 05/06/21 at 16:13:07:
I think I alredy sumarised.. but in case, dont drive naked on a bike, and dont even think about that a lighter flyweel gonna afect accelration on any bike.. except clutch time on a racing track. Smiley


On my bike going from the stock flywheel to the mid-weight flywheel reduced my 0-60 times by 1/2 second.  My GPS speedometer has a 0-60 timer and I made several runs with the stock flywheel and my times didn't vary much.  I don't really do a drag race start and rev the engine and drop the clutch - but I did try to leave the line quickly and consistently.  I went home and leaned the bike over on the right side and changed the flywheel as quickly as I could.....with my Cafe' bike I can remove the left side cover without having to remove the foot pegs.  I then went out and made more timed runs with the mid weight flywheel.

My times with the lighter flywheel were consistently 1/2 second quicker.  I could not tell any difference in the smoothness of the idle or any change in vibration while riding....and the seat of the pants really could not feel the change in acceleration - but the timed runs showed there was a change in the rate of acceleration.

DragBikeMike tests in a different manner - he times his acceleration in 3rd gear between 4,000 and 7,000 rpm.  The way he tests eliminates the variance in getting a good start or shifting gears.  Hopefully his upcoming tests will show what (if any) changes in acceleration he has with the light flywheel.

   
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