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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Flywheel Lightening /cgi-bin/YaBB.pl?num=1421784605 Message started by paulmarshall on 01/20/15 at 12:10:05 |
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Title: Flywheel Lightening Post by paulmarshall on 01/20/15 at 12:10:05 Has anyone done this and if so how does it affect the low rev vibration? My understanding is it helps in high revving. Is what this guy in this video takes off a good indication of what I can take off my Savage flywheel? https://www.youtube.com/watch?v=XvlliZrEAow |
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Title: Re: Flywheel Lightening Post by zipidachimp on 01/20/15 at 13:04:56 shade-tree machinist! sure wish I understood what the consequences are of dropping flywheel weight by 1/3 ! |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/20/15 at 13:42:48 54475E474A4F4D4647435E2E0 wrote:
Faster acceleration I think. |
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Title: Re: Flywheel Lightening Post by verslagen1 on 01/20/15 at 13:42:59 When is the flywheel necessary: 1. Starting . the decomp activates and the starter spins the crank up to a minimum speed to overcome the compression cycle. 2. Running . compression cycles take power to complete . power cycles puts power into the flywheel. A heavy flywheel dampens power input, puts less strain on transmission. On a system that can eat up main output shafts, I'd hate to increase the tendency. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/20/15 at 13:50:51 I was advised by my local bike shop to try it. I am seriously considering trying this. Considering our engines put out very low HP I don't think a lightened flywheel will hurt our transmissions. If they do our trannies must be made from plastic. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/20/15 at 13:56:10 22312627383533313A65540 wrote:
Dont we increase the tendency's when we upgrade our jets,air filters,exhausts, cams,pistons etc etc |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/20/15 at 14:01:39 Suzuki left so much room for improvement ie Jets,exhaust, etc that we take advantage off why ignore the flywheel which with a little lightening can proved major gains. https://www.youtube.com/watch?v=KHz7L35Y454 |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/20/15 at 15:11:40 Factory Jetting is not for the engine,but for EPA regs. Motor has not changed, jetting has. I've wondered if the counter balance might not be just right for the piston and rod. If I was going in far enough to crack the case, I'd wanna start there. If anything had to lose weight to balance ,,great.. If you can get the flywheel and not go all the way in,then I'd first check its balance, then mass, then consider how to and how much to lighten. A percentage of mass ,, gotta be some kinda guidelines out there.. Www.lightenmyflywheelnow.please |
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Title: Re: Flywheel Lightening Post by Dave on 01/20/15 at 15:12:23 The heavy flywheel stores rotating energy, and helps to even out the power pulses and the compression stroke.....it makes the engine run smoother.....most noticeably at lower rpms. Would the bike be quicker with a lighter flywheel....Yes. Can the clutch handle your 97mm piston and a light flywheel...Dunno! Can you lighten the flywheel a bit.......Sure! When I was playing with VW bug engines...we lightened the flywheel to make them quicker. When my friend had a 1973 Suzuki TM400 motocross bike - they bolted an extra flywheel weight on them to try and make them less likely to spin the rear wheel as the power just came on to suddenly. Flywheels store energy, and do help you to get moving from a stop. When you lighten the flywheel you have to slip the clutch a bit more, or use a few more revs to make up for the loss in stored energy....the engine does become easier to stall when pulling away from a stop. Maybe Suzuki has so much flywheel to help new riders avoid staling the engine while they learn how to ride. The Savage has a heavy crankshaft, heavy flywheel, and heavy rotor....most likely you can lose a little bit of that weight and still be OK - I have no idea how much, and you need to be aware that the farther the distance from the center of the flywheel....the more energy is stored. (Remember how the ice skaters speed up when they are spinning and they pull their arms in? They spin faster as they reduce the "moment of inertia" when their arms are no longer swinging on a long path and are held close to their body). The end result is that if you are removing weight from the outside diameter of the flywheel.....it will reduce the inertia a lot. Will you be the first one to try it on this motor....Most likely. PS....If you want to see what happens if you lighten the flywheel too much. Go to the garage and find your push mower. Turn the mower on it's side, remove the blade, turn the mower upright.......now try to pull the starter cord. With no momentum....you most likely can't get the engine to turn over a single revolution. Push movers have an aluminum flywheel and use the blade mass as the flywheel. |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/20/15 at 15:26:52 Might be asking a bit more from the hub rubber.. Didn't see the Fat Piston... Call someone who can Sell you a flywheel ,ask what the shipping weight is. I'm looking forward to seeing where this thread goes. Might hafta raise the idle. Something hasta swing that thing thru the exhaust,intake and,as noted,COMpression stroke. Knowing EGGzaklee where the neato magneto stuff is would be good.. I think I've seen it,but don't remember for sure. I Really want this to be doable and beneficial. Please dyno or at least do some test runs,zero to sixty,and other stuff before and after. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/20/15 at 16:57:21 Thank you Dave and Justin very informative as usual. I see that what the guys in the videos call a fly wheel our parts list calls a Rotor. Sorry for the confusion Title should read Rotor lightening. :-[ |
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Title: Re: Flywheel Lightening Post by Serowbot on 01/20/15 at 17:13:13 Save a lot of work,.. just buy a Shinko 712 rear tire... it's a lot lighter than most other tires... ...and don't buy "heavy duty" tubes... don't run "Slime" in the tubes... ...and stick with the belt drive... Less flywheel effect... faster acceleration... won't ruin yer' engine... JMHO... :-?... |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/20/15 at 17:18:33 3E283F223A2F22394D0 wrote:
But what if I did both. Im really curious to see if a lighter rotor/flywheel stator will have any benefit. I already have a spare one which my buddy can mount in a lathe. Now that we are clear thats its the rotor and not the actual flywheel thats being lightened, there shouldn't be too much issue with crank balance and such should there? |
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Title: Re: Flywheel Lightening Post by Serowbot on 01/20/15 at 17:23:29 I don't know... I got the feeling we're going to find out... ;D... Best luck... ;)... |
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Title: Re: Flywheel Lightening Post by Flint on 01/20/15 at 19:00:16 Trials bikes used to have a heavy flywheel just to store energy. Makes it easier to pop the clutch and make the bike hop up things with a tiny motor.. Personaly, unless you were planning on going to try out for the Isle of Man race, I would leave the flywheel alone. Nothing ventured... nothing gained, as they say. I would be interested how it works out. |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/20/15 at 19:45:41 Awwrite,, you physics guys, re,,,angular momentum. Now, take a metal disc, say, diameter, ten inches, thickness, three. So. If you take the weight off of the perimeter, how different would that be from taking the same weight off, but just as close to the center as possible? IOW, Well, should we see the Flywheel Effect of every cubic millimeter of the flywheel change as we progress outward from the axis and if we do,would it look anything like the Calculate Perimeter of a Circle formula? And,if so,can we figure how much to take AND where to take it? |
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Title: Re: Flywheel Lightening Post by Serowbot on 01/20/15 at 20:58:24 I sure can't... ;D ;D ;D ... |
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Title: Re: Flywheel Lightening Post by Dave on 01/21/15 at 04:13:49 The Polar Moment of Inertia can be calculated for the circle and the material removed. For the crankshaft and rotor this would be difficult to do - as they are not common circles and they are made up of different materials. For the flywheel it would be pretty easy to do as it basically a flat disc. Let's assume the disc is the 10" diameter that JOG wanted. The Polar moment of inertia is PI/2 x the radius cubed.......981. If we were to reduce the flywheel to 9"....the Polar moment of inertia would be reduced to......644. If we were to take 1" of material out of the middle (which is impossible as the connection to the crankshaft would be gone).....the Polar moment of inertia of a 1" diameter disc is 1.57 (small because 1 cubed is still 1). So if you took the 10" sphere that has a Polar moment of inertia of 981, and took the 1" out of the middle which has a polar moment of inertia of 1.57....the result is a polar moment of inertia of 981 - 1.57 = 979.43. Taking 1" off the outside reduces the polar moment of inertia by 34%, while taking 1" out of the middle reduces the polar moment of inertia by only 0.16%. This is why driveshafts, columns, handlebars etc. are all made hollow....it reduces weight and has a very small effect on the strength (and/or energy stored the rotating mass). Have you ever noticed that most flywheels have most of the mass located on the outer circle? This allows the flywheel to be as light as possible - while storing the most amount of energy possible. The bottom line is - you want to take as much weight as possible off the outside of the flywheel if you goal is to improve acceleration....and take off as much weight as possible from the center of the flywheel if your goal is to reduce weight and keep the polar moment of inertia high. As an example...if you were to remove the center 8" from the disc, the Polar moment of inertia would be 981 - 402 = 579(59%) - while the area (and weight) would have been reduced from 78.5 - 50.2 = 28.3 (36%). So you would get bit less than 59% the inertia at 36% of the weight. On the Savage engine - I would not recommend taking weight off the rotor. You will get far more effect by taking material off the outside of the flywheel. |
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Title: Re: Flywheel Lightening Post by Dave 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 [media]http://www.youtube.com/watch?v=ERrpxCfEkqc[/media] |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/21/15 at 08:19:24 I was never the great answer guy, OHHH, but if someone could answer the questions,,, we could make stuff Happen.. I STILL wanna see the graph of a dot on a wheel ( both speed and position, one above the other). The dot, ( The theoretical dot, uz it is on the surface that touches the road) and it stops when its on the road and is going twice the speed of the car on top. Yes,, I have an active imagination.. Ohh,, and thank you Dave,, I know my old lab partner in Chemistry coulda sat me down and explained it.. I did the labs, the hands on stuff,, he did the paperwork, we smoked it,, good grades, out early if not first,, dang that dude was SHMAAAAART.. Ohh, yea,, and I told a guy who used to be here a lot about this,, he mumbled something as he hung up to go get steaks on the grill,,,, Then,, after he ate, he called back,, RARELY do we speak twice in a day,, So,, he musta had sumthin to say.. He was a hot rodder as a teen and young man,, and pointed out that Yes, this will work, but that working on the reciprocating elements will also increase top RPM AND decrease spin up lag,, so, yea, lighten rotating mass,, and dont thknk the clutch isnt a drag,,, if you can get a lighter clutch pack in it, and, of course, the crank, piston and rod and counterbalance all come into play in a Big Way.. That said,, high RPM on a Long Stroke equals Crazy piston speeds,, and on the exhaust stroke, the piston is ONLY held down by the rod , so, when the crank throw gets to its end and is heading back down,, the rod is suffering. So, a lighter piston on a rod thats designed for that kinda punishment,, yea,, you do the math.. How many miles have ya got on the thing since you went to the Wiseco? What rear tire ya runnin? How much time do you spend at highway speeds? The way Im readin ya,, YOur goal isnt to jack up ythe high end RPM, but to just unburden the engine so it can rap up TO its max quicker,, as in, I wanna a little street sleeper, dont look scary quick,, BUT,, will come off the line like a Warthog goin at a Lion thats just crossed the line.. leaving any Harleys in the immediate vicinity in the dust.. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/21/15 at 12:18:42 3E2127203D3A0B3B0B33212D66540 wrote:
Justin I still haven't done a lot of miles on the Wiseco yet :-[ and my reasons for looking at lightening the Rotor was 1) I will be opening up that side of the motor when I replace the Starter Idle Gear, 2) My mechanic suggested it would help improve acceleration and top end revs. I do trust him and he speaks from personal experience, but he didn't do it to a Savage but the principles should be the same. The rear rim is a 4.25x16 with a 170 tire but because the rim is alloy it is lighter than the stock. I live in a small town so road speeds out of town are 100KPH. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/21/15 at 12:23:32 7F44495E4F43585E454D405F2C0 wrote:
This was a very hard video to follow sorry :-[. 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? |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/21/15 at 19:00:18 I caught up with a friend today who owns a BMW 650 single who has had his rotor/ flywheel lightened, and he said that their were huge improvements in acceleration. He did continue to say that his riding style had to change. He described it to riding a electric motorcycle where one would experience re-gen when releasing the throttle. He commented that he uses the break less because the bike slows down like a electric re-gen. He also said that with a stock heavy rotor/flywheel once up to speed it holds speed smoothly where with a lighter rotor/flywheel slight deceleration you start to slow down quickly. But I reckon like a electric motorcycle practice makes perfect and in time it will become second nature. I am glad I have talked to someone who has done this and done it some years ago without mishap. The fact he has kind of a similar engine being a single 650 make me think I will have similar gains. I find it interesting to bring something else to the mix apart from the upgrades we all know and love for so many years. Isn't it nice to think outside the norm and try something new. I will try this but unfortunately I wont be able to show any results as the motor is sitting in the corner under a sheet. Due to the fact I am ordering parts as I can afford for the Cafe build. However I will machine the spare one over the next week or so and take pics. If someone else out there wants to pioneer the idea go for it. |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/21/15 at 20:19:37 That's good news. Go get them,dude.. . Bummer about the Can't prove improvements... ohh well... Dave, my lab partner did the math, mmmmkay? I'm not gonna track well, I need someone to talk to,ask questions, and then MAYBE I'll get it. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/21/15 at 21:08:53 Im thinking about taking off small amounts at a time instead of taking a third off the bat. I have a spare rotor/flywheel and Im going to get a puller so at a cost of gaskets I can test and remove the rotor/flywheel, remove more metal refit and test. Try to find a good balance. Its just so frustrating I cant test these now. :( |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/21/15 at 21:13:31 I'd get it running, get some miles on it, break it in, run some time trials, then step into the flywheel.. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/21/15 at 21:15:34 5D4244435E5968586850424E05370 wrote:
Good point |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/21/15 at 21:31:22 I'm old... [ch128521] Keep notes on performance as you work the flywheel. Keep up with Exactly what is coming off the flywheel. You make a cut and see a problem, you can cut the other flywheel to the best performance specs.. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/21/15 at 21:38:51 77686E6974734272427A68642F1D0 wrote:
You sir have hit the nail on the head. Thats exactly what I will do. Trust me I will follow through with this. |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/21/15 at 21:43:15 Glad to be some help... |
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Title: Re: Flywheel Lightening Post by Dave on 01/22/15 at 03:15:11 6D7C6871707C6F6E757C71711D0 wrote:
This was a very hard video to follow sorry :-[. 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?[/quote] 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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Title: Re: Flywheel Lightening Post by Dave 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. |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 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? |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/22/15 at 10:57:01 68535E4958544F49525A57483B0 wrote:
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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Title: Re: Flywheel Lightening Post by paulmarshall on 01/22/15 at 11:14:12 57484E4954536252625A48440F3D0 wrote:
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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Title: Re: Flywheel Lightening Post by paulmarshall 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? |
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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 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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Title: Re: Flywheel Lightening Post by Dave on 01/22/15 at 12:41:15 5746524B4A4655544F464B4B270 wrote:
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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Title: Re: Flywheel Lightening Post by paulmarshall on 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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Title: Re: Flywheel Lightening Post by justin_o_guy2 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. |
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Title: Re: Flywheel Lightening Post by paulmarshall on 01/22/15 at 13:33:54 7A656364797E4F7F4F77656922100 wrote:
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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Title: Re: Flywheel Lightening Post by justin_o_guy2 on 01/22/15 at 13:46:24 You da Man! |
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Title: Re: Flywheel Lightening Post by Dave on 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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