SuzukiSavage.com - Flywheel Lightening

Dave

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Re: Flywheel Lightening
Reply #30 - 01/22/15 at 03:15:11

paulmarshall wrote on 01/21/15 at 12:23:32:

Dave wrote on 01/21/15 at 04:58:14:

And.....if you need to know how to derive the formula for the Mass Moment of Inertia (I used the Polar moment of inertia for area as I do not know the mass).

https://www.youtube.com/watch?v=ERrpxCfEkqc

This was a very hard video to follow sorry Embarrassed

. How ever I did pick up near the start where he said about 1.20 min into it, " It didn't matter how thick the ring was this way and I'm assuming its pretty thin this way" So in layman"s terms my understanding is it doesn't matter how wide it is but does matter how thick it is?

In this discussion he was working on the Moment of Inertia of a 2 dimensional disc. For a flywheel it would be necessary to calculate the thickness and mass to quantify the Mass Moment of Inertia for the flywheel. If the flywheel is a disc, or different combinations of discs and rings it is not all that hard as you can break it up into individual rings of varying thicknesses and calculate the mass moment for each piece and add them up.

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Dave

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Re: Flywheel Lightening
Reply #31 - 01/22/15 at 03:49:23

The rotor is made of several components, and it does not appear you can take any material off the outside diameter.

It does appear that you could take some material off the backside of the rotor. The outer ring appears that you could cut it back flush with the backside of the rotor.

The flywheel is a flat disc, and it appears it could easily be cut down, and the most benefit comes from taking material off the outside diameter. The difficulty in this is finding a way to hold the flywheel on the lathe....the left side of an old crankshaft used as a mandrel would be the best way to hold onto it in a lathe.

I would start by taking some material off the back of the rotor. Cutting the ring off the back of the rotor would likely make very little difference - not sure if you would even notice it.

And to comment about the different feel - my bike feels that way compared to a stock engine. I have a 95mm Wiseco, Stage 1 cam and a Mikuni round slide. The extra compression and carb make it so that when you let off the throttle - the engine has a lot more compression braking and it slows down faster. You can hold a steady speed by holding a steady throttle - but when you move the throttle the bike either accelerates or decelerates depending on which way you moved the throttle.....it is more responsive. You soon learn that you don't just close the throttle....you roll it off until you get to the amount of deceleration you want, and you roll on the throttle until you get the acceleration you want. It is not the ideal situation for cruising down the interstate for hours on end - but works just fine on the local back roads where the speed varies continually.

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justin_o_guy2

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Re: Flywheel Lightening
Reply #32 - 01/22/15 at 07:52:39

IF I wuzgunna seriously try to wring every bit of performance outta the Savage I'd combine what some of these guys have done. I'd get an engine, so I could ride, and I'd bore it,treat the cylinder, put a cam and carb on, I'd put a tuned air box on and clean the head up and either build or buy a tunable exhaust, and, I'd hafta get to the crankshaft and counter balance and all that stuff so as to lighten and balance everything as much as possible.
Consider the stroke, and then the mass of the piston, now, consider maximum RPM and see how fast the piston is moving and understand that at the top of the exhaust stroke, the rod is really in a bind. At the bottom of the power stroke,the rod is being crushed. So, decreased mass is important.
High R PM long stroke engines aren't real common.
I know the goal is to rev quick, not so much for higher top end,
Remember, everything that has to SpinUp has inertia and impedes that SpinUp, so, look at the clutch,too.
Look at the shipping weight of the tires.
You know, before fiberglass was The Answer some guys were acid dipping their fenders and stuff. Lighten up the bike and pay close attention to unsprung weight. If you don't change that BUT you lose twenty-five pounds off the bike, I'd expect you to feel it and not like it.

Are there clutch disks available that weigh less?

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paulmarshall

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Re: Flywheel Lightening
Reply #33 - 01/22/15 at 10:57:01

Dave wrote on 01/22/15 at 03:49:23:

The rotor is made of several components, and it does not appear you can take any material off the outside diameter.

http://i62.tinypic.com/2ykgec6.jpg

It does appear that you could take some material off the backside of the rotor. The outer ring appears that you could cut it back flush with the backside of the rotor.

http://i61.tinypic.com/25gc7m8.jpg

The flywheel is a flat disc, and it appears it could easily be cut down, and the most benefit comes from taking material off the outside diameter. The difficulty in this is finding a way to hold the flywheel on the lathe....the left side of an old crankshaft used as a mandrel would be the best way to hold onto it in a lathe.

http://i62.tinypic.com/15oz2iu.jpg

I would start by taking some material off the back of the rotor. Cutting the ring off the back of the rotor would likely make very little difference - not sure if you would even notice it.

And to comment about the different feel - my bike feels that way compared to a stock engine. I have a 95mm Wiseco, Stage 1 cam and a Mikuni round slide. The extra compression and carb make it so that when you let off the throttle - the engine has a lot more compression braking and it slows down faster. You can hold a steady speed by holding a steady throttle - but when you move the throttle the bike either accelerates or decelerates depending on which way you moved the throttle.....it is more responsive. You soon learn that you don't just close the throttle....you roll it off until you get to the amount of deceleration you want, and you roll on the throttle until you get the acceleration you want. It is not the ideal situation for cruising down the interstate for hours on end - but works just fine on the local back roads where the speed varies continually.

Dave if your experiencing the same symptoms of driving response from known proven upgrades then that tells me removing some material from the rotor is helping in some way or form.

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paulmarshall

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Re: Flywheel Lightening
Reply #34 - 01/22/15 at 11:14:12

justin_o_guy2 wrote on 01/22/15 at 07:52:39:

IF I wuzgunna seriously try to wring every bit of performance outta the Savage I'd combine what some of these guys have done. I'd get an engine, so I could ride, and I'd bore it,treat the cylinder, put a cam and carb on, I'd put a tuned air box on and clean the head up and either build or buy a tunable exhaust, and, I'd hafta get to the crankshaft and counter balance and all that stuff so as to lighten and balance everything as much as possible.
Consider the stroke, and then the mass of the piston, now, consider maximum RPM and see how fast the piston is moving and understand that at the top of the exhaust stroke, the rod is really in a bind. At the bottom of the power stroke,the rod is being crushed. So, decreased mass is important.
High R PM long stroke engines aren't real common.
I know the goal is to rev quick, not so much for higher top end,
Remember, everything that has to SpinUp has inertia and impedes that SpinUp, so, look at the clutch,too.
Look at the shipping weight of the tires.
You know, before fiberglass was The Answer some guys were acid dipping their fenders and stuff. Lighten up the bike and pay close attention to unsprung weight. If you don't change that BUT you lose twenty-five pounds off the bike, I'd expect you to feel it and not like it.

Are there clutch disks available that weigh less?

justin I do have some of the upgrades that you have mentioned here and seriously looking at a cam and flat side carb. In saying that I don't want to stress the motor to the point of destruction. Sporting mods not racing mods. I would not go reducing weight in the crank or counter balance as that's set up optimally for a sooth running engine.Removing material from their will unbalance things Im thinking.

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paulmarshall Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1268 Carterton,New Zealand Gender:	Re: Flywheel Lightening Reply #35 - 01/22/15 at 11:22:06 Dave and anyone else that has fitted a stage 1 cam, Can you please tell me how this has affected your bikes at idle?
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justin_o_guy2

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Re: Flywheel Lightening
Reply #36 - 01/22/15 at 12:00:14

Well, if you bored it and the piston weighs different, and exactly how perfect was the factory balance between piston and rod and counter balance,, who knows?

I had the stage 1cam, OEM carb,main jet changed, pilot broke an ear off and I called it good enough. Don't remember the main jet size settled on.
I wanna say that the cam was almost as effective in acceleration as the Supertrap was, but, I don't REALLY know that.. I do know that it was a Bunch quicker in the Zero to Sixty after the mods. How much was exhaust,how much was cam, how much was it the mods in the airbox,,I increased the volume between the filter and carb, how much was it my getting quicker on the gas and shifter?
I didn't go at it Scientifically,and regret that.
Take your time, test before and after every step, be able to document improvements or effort for little or no gain. You can play a role in helping others know what is worth doing and what gives the best Bang for the Buck.

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Dave

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Re: Flywheel Lightening
Reply #37 - 01/22/15 at 12:41:15

paulmarshall wrote on 01/22/15 at 11:22:06:

Dave and anyone else that has fitted a stage 1 cam, Can you please tell me how this has affected your bikes at idle?

My engine idles just fine, gets good gas mileage, and really doesn't have any bad manners that you would associate with a wild cam.....the Stage 1 cam is still a pretty mild cam grind. The Stage 3 cam is the same duration with a larger lift, the Stage 2 cam has the larger lift and longer duration - but still is not a wild race cam and the one bike I have seen with that cam idles and cruises just fine.

And lightening the flywheel will allow the engine to accelerate a bit faster - it will not do anything to allow you to increase the maximum rpm. This engine needs to be built to make torque and HP below 7,000....spinning it up faster will not do anything as the head restrictions will not allow the engine to breath up there.....and when you get up there the cylinder starts to do weird things like burn oil and makes lots of stuff out the breather.

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paulmarshall

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Re: Flywheel Lightening
Reply #38 - 01/22/15 at 12:53:05

Thanks Dave I was thinking about the stage 2 but was worried about its daily running characteristics.
I have done some mods towards helping the engine breath.
1) Port and polish the head.
2) Removed metal and opened up exhaust outlet on the head.
3) Larger header with out the restrictive liner.
4) Custom muffler
5) Cone air filter
I almost forgot the most important 97mm piston. Not sure if a bigger piston constitutes helping the engine breath.

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justin_o_guy2

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Re: Flywheel Lightening
Reply #39 - 01/22/15 at 13:28:15

The stock header has a metal, funnel looking doodad up by the head. I was told it is there to keep reflected pulses from slapping into the exhaust pulse.
Just building a pretty tube with a bigger hole in it is no guarantee that the engine will run better. Header design theory and intake design theory matter. I don't understand the desire to throw out the airbox by so many.
I don't understand the " I'll build a zero back pressure exhaust"..
Knowing the volume of the cylinder and the RPM range where we Really want to see it pull hard, then can't we calculate the volume of the pipe and design it to be delivering another pulse to the reflected pulse that the baffling the muffler is causing?
Not that I have the answers, but I have to believe that there is a scientific approach to it, may not Dead Bang nail it, but getting more out of it shouldn't just be a Lets toss money and time at it and see
Kinda deal.

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paulmarshall

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Re: Flywheel Lightening
Reply #40 - 01/22/15 at 13:33:54

justin_o_guy2 wrote on 01/22/15 at 13:28:15:

The stock header has a metal, funnel looking doodad up by the head. I was told it is there to keep reflected pulses from slapping into the exhaust pulse.
Just building a pretty tube with a bigger hole in it is no guarantee that the engine will run better. Header design theory and intake design theory matter. I don't understand the desire to throw out the airbox by so many.
I don't understand the " I'll build a zero back pressure exhaust"..
Knowing the volume of the cylinder and the RPM range where we Really want to see it pull hard, then can't we calculate the volume of the pipe and design it to be delivering another pulse to the reflected pulse that the baffling the muffler is causing?
Not that I have the answers, but I have to believe that there is a scientific approach to it, may not Dead Bang nail it, but getting more out of it shouldn't just be a Lets toss money and time at it and see
Kinda deal.

I agree about the math behind headers and exhausts. You can have too big of a exhaust which will cause the bike to run like rubbish. I had my header and muffler made by a professional for optimal gains. I don't do any mods until I have done all the resurch first.

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: Flywheel Lightening Reply #41 - 01/22/15 at 13:46:24 You da Man!
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Dave

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Re: Flywheel Lightening
Reply #42 - 01/22/15 at 16:36:16

The 97mm piston won't help with the head flow any....it just uses up the available air supply at a lower rpm than the 94mm did.

The 97mm piston gives you more torque. Since HP is torque x rpm....it may not be able to give you more HP if the engine runs out of air at higher rpms. Cleaning up the ports and opening up the exhaust can help - but it is still a very bad design when compared to a bike that is designed for moving a lot of air and making HP.

I am not trying to Poo Poo your proposed "upgrades"....I just want to try and bring some reality into the engine build. If you try and push this engine too hard - you will likely loose some of the characteristics of the engine that make it so agreeable and easy to live with.

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« Last Edit: 01/23/15 at 04:52:32 by Dave »

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