lightened flywheel on an eldo?

[amamet]

im getting my parts together to send off to lindskog for balancing and came across a v11sport 10 spring flywheel setup I had squirreled away.  already has an iron lined big bored kit that I doubt was ever balanced, that's why its going there. im not touring with this bike and I know people like the heavy flywheel for its rideability.  I have a custom set of heads that take 36mm dellortos that mike rich built (these were purchased from Charlie Coles estate). I need to make sure they work with the pistons I have.  mike told me he built those heads with specs from the pistons (which were lost somewhere in charlies basement). just wondering if im losing too much smoothness by not using the heavy flywheel
thx
allen

[lazlokovacs]

I had my loop apart about a month ago with a beatiful HMB lightened flywheel on the shelf

I thought about it for about 15 seconds then remembered just how much I always loved that beautiful torquey locomotive feeling from the loop

I'd keep it stock

[guzzisteve]

Went & traded bikes today at my storage space, been 4mo. 67 V700 started right up, rode it home & swapped EV went back. 67 has a flywheel 30% lighter than a Tonti in it & it's a joy to ride. Spins up nice but plenty torque to putt around. My Cali2 sidecar rig has a heavier V700 flywheel. Needs the heavier torque spinning for the 250# chair out in the breeze. I have one in a box that looks like Swiss cheese, weigh's 9.4# for my LM3 waiting to get finished & money.

[cliffrod]

 I can’t attest to a Loop, but the difference of riding back-to-back on my V7 Sport (stock weight flywheel) and CX100 (significantly lightened flywheel) is very noticeable.  The CX revs and shifts/downshifts more like a Ducati twin than a Guzzi. 

Not planning to change CX back to stock right now, but it doesn’t feel the way I have come to expect a Guzzi to feel.  On a modified sport bike,  it’s not a big deal to me.  but it is a very different experience in terms of character.  not sure I would want to have an Eldo/Ambo to feel like this.

[Huzo]

Just to clear a little something up…
The heavier flywheel does not increase your torque output, it flattens the delivery. Torque is produced by the con rod pushing down on the crank pin and increasing the rpm, thereby the power.
Power = torque x rpm
The flywheel is a storage unit for energy and that energy is supplied by the spinning up of the crankshaft. So if a flywheel has a certain potential energy @ 4,000 rpm and is increased to 5,000 rpm, the energy it took to spin up that extra 1,000 rpm, is there to be used when you decide to ask it to do work and you can use that energy as you go from 5,000 to 4,000 rpm.

A heavy flywheel does not boost your torque, it just evens out the distribution.

[jhem68]

I have an Eldo (stock motor) with a ram clutch installed and the effect mirrors the reply from guzzisteve.
Whether the other mods you're doing would amplify that effect or whether or not that result would be what you want is for you to decide.
I needed a lighter clutch pull and wasn't sure I would enjoy the change in character, but it turns out that I was very pleased with the results. Around town or in stop and go traffic it is more responsive and still retains all of the good "feel" that these motors produce.

John H

[lazlokovacs]

A heavy flywheel does not boost your torque,

I hope you're not suggesting for a moment that I suggested otherwise my good sir??

A heavier flywheel obviously can't increase torque but it can feel more torque-y.... speaking from a world of subjective experiential epistomology.. or something

 

[guzzisteve]

OK Huzo, changed my wording in thread to reflect your explanation of torque, I hope you like it. I am just a farmboy, not an English major. I also have a hard time explaining things that I feel.

I had trashed the drivetrain on the Cal2 in 30K mi running the sidecar:Clutch, ujoint, driveshaft splines, rear drive. 
I also wondered why loop bikes didn't in my experience, so, thought it may be the heavier flywheel, I was correct. This set-up has gone 100K and now needs pretty much same thing. One reason it doesn't travel far from home, cuz I don't want to haul it back that far.

[Turin]

I'm a big fan of lightened flywheels. I have a RAM in the Cal III, A Transkontinental in my silver/greem custom, A seriously lightened stock item in the Dav's Cycle lemans SE. Even my 850 Has some minor lightening around the outside of the flywheel.
 
That said, I don't think I'd lighten the flywheel on my loop. Seems like it would be out of character for such a tractor of a bike.

[Huzo]

The description was for the general (I hope), information of those who find it interesting. I do not presume to know who understands certain terminology and who does not, but I constantly hear mashed up descriptions of real world stuff and just like to shine a light if I can..

[Huzo]

OK Huzo, changed my wording in thread to reflect your explanation of torque, I hope you like it. I am just a farmboy, not an English major. I also have a hard time explaining things that I feel.

I had trashed the drivetrain on the Cal2 in 30K mi running the sidecar:Clutch, ujoint, driveshaft splines, rear drive. 
I also wondered why loop bikes didn't in my experience, so, thought it may be the heavier flywheel, I was correct. This set-up has gone 100K and now needs pretty much same thing. One reason it doesn't travel far from home, cuz I don't want to haul it back that far.

If you want to, can you tell me why you think the heavier flywheel contributed to the greater longevity of the drive train ?

[guzzisteve]

It's the only item different. All the loop sidecar rigs I experienced in going to sidecar rallies & friends rigs since early 80's never had issues.
I ride it like a sports bike. It'll pull rig over 100mph!! I don't baby it at all. Can't really say, maybe like you said it spreads the torque out more. That may be less stressful on components. It has lasted 3 times longer. I put in deep spline hub & plates & auto adjust timing chain adjuster at same time in 93, I don't think that made it last longer. That just came available at the time.

sorry, you said it evens out the distribution of torque------------got to be extra correct on here, sorry
 

[John A]

If you want to, can you tell me why you think the heavier flywheel contributed to the greater longevity of the drive train ?

If I can jump in I’d say it was because the heavier flywheel dampens power pulses and the clutch can be let out with a minimum of slippage. I get better mileage on driveline components when I keep the driveline ‘tight’ by running in a gear that allows throttle control ie a minimum of coasting. A lighter flywheel makes that more fun.

[cliffrod]

A casual rule of thumb for automotive flywheel selection is to have 10 lbs of flywheel for 1000 lbs of vehicle weight.  Because of the higher potential for stored energy in a heavier flywheel, Heavier vehicles benefit from heavier flywheels because there is more stored energy to move the mass more easily.  Other factors like final gear ratio and intended use (regular driving, heavy towing, high performance) factor into the equation.  Heavy towing and regular driving tend to benefit more from heavier flywheels.  High performance engines anticipating extensive high rpm use, not as much. 

In the early years (for example) the Ford Model A weighed approximately 2350 lbs with a 40 hp 201 ci 4 cylinder equipped with a 62 lb flywheel. (Closer to 30lbs:1000lbs) The heavier flywheel mass allowed more energy to be stored from the relatively low power output engine to make the vehicle much more drivable.

As time passed, Manufacturers moved towards the 10lb:1000lb ratio but often seemed to err on the side of lighter flywheels in many cars.  A 1967 Ford Mustang with a 390 FE (considered to be an high performance musclecar) engine weighs approximately 3400 lbs and uses a 28 lb flywheel. Not quite 10 lbs per 1000 lbs but close.  A 1967 Ford Galaxie with a 390 (or 427) FE engine weighs approximately 4100 lbs while being equipped with the same 28 lb flywheel.  I opted for a heavier flywheel, closer to 40 lbs, for my current 1967 Galaxie 427 project to more closely follow the 10 lb per 1000 lb ratio.  When this topic is discussed online, there is generally some level of debate similar to an “oil thread.”   

But this thread is about motorcycle engines & flywheels, specifically about using a 13lb flywheel in a 600-ish lb bike which is closer to 20lb per 1000lb of vehicle weight.  the only parallel I can see is that both a Moto Guzzi V700 and a Ford Model A sometimes had a 4-digit vin, which can make title work at the dmv be a PIA….

[guzzisteve]

Just so you know, I weighed flywheels & ringears ------------------Tonti is 18.2 and my Swiss Cheese is 9.4 didn't do a loop but they are considerable more. Just so you know. The guy that cut my light weight is Bob Bourdson from WI and he retired, don't know if anyone got his program for CNC The one in my 700 was cut by Ace in MO, done same time I put one in an Aluminum custom I built in 09.

Thank You Clint for your explanation

[cliffrod]

Just so you know, I weighed flywheels & ringears ------------------Tonti is 18.2 and my Swiss Cheese is 9.4 didn't do a loop but they are considerable more. Just so you know. The guy that cut my light weight is Bob Bourdson from WI and he died, don't know if anyone got his program for CNC The one in my 700 was cut by Ace in MO, done same time I put one in an Aluminum custom I built in 09.

Thank You Clint for your explanation

You’re welcome, Steve.  Us farm boys need to stick together.

Thinking along the same lines, I did a quick online search of BMW /2 flywheel weights.  One post listed a R60/2 flywheel at 13.2 lbs (5.5 kg) vs R69S at 9 lbs (4kg).  When I had my R69S and was learning about that scene while thinking about cool Steib sidecars & how one would seem to be a better match for the higher hp R69S vs a plain R60/2, I was advised it was not a good combination.  Part of the reasoning was that the R69S has a much lighter stock flywheel than a regular R60/2, which did not benefit operating the heavier outfit. The heavier flywheel would be better suited for typically lower rpm sidecar use vs higher rpm solo performance use, so that “what if?” for my bike went to the wayside.

[Bulldog9]

I remember an old racer tell me years ago

Light Flywheel for bracket racing and fast motor spin up

Heavy/Stock Flywheel for road racing and access to torque.

[guzzisteve]

I thought I weighed the loop on installation and got 27# but may be 23, I'll do one later, got plenty. Sold a perfect ringear last week for $50 out of loop going in an Ambo.
While on this subject, I used a cindered bronze clutch in the LM3, was supposed to be lighter than stock ones. The splines are now pretty sharp. I have another set but they have 3 plates & 2 center pieces. Just wondering if anyone else has used these?  Made by same Surflex.

Edit: Measured a loop flywheel w/o ringear and was 18.2# for just flywheel. Didn't feel like going through a bunch of boxes to find a ringear.

[Moparnut72]

When I raced outboard powered boats one class I ran was Cmod. The motor was a 4 cylinder 2 stroke Mercury. I didn't run a flywheel at all. Acceleration out of the turns was more important than top speed. On the other hand I grew up in Mystic Ct where Lathrop Marine, a marine engine manufacturer produced engines. They were a large single cylinder 4 stroke with a single or paired 3' flywheels. They were used in fishing trawlers. When they were going down the river at a decent speed I could easily count the combustion events. Those engines were legendary for the ability for dragging large nets quite easily while getting exceptional fuel economy.
kk

[jacksonracingcomau]

My 2c on heavy flywheels

A relic from the steam age, perhaps still pertinent to cars, trucks, sidecars, maybe even those 3 wheel can-ams and such. Modern thought has rejected them for solos, modern bikes (notably Guzzi and BMW-previous advocates) have gone completely away from such madness.
I do still wonder why Carcano fitted them to original V7
Perhaps H-D were on that page and therefore the market to chase ? Whatever, the idea is dead now.

Yes, I have swiss cheese (@guzzisteve) one in my V700 and even lighter (alloy twin plate) in my Le Lans. Even my SB has ring gear holier than Rome.

Why ?
Gear change — flywheel weight slows down the slowing down of motor just like it slows down the speeding up. So gear changes are way easier and quicker.

Engine braking-  I ride by the box, see above

Acceleration— sorry, no excuse, I just like it !

Yet I fully understand we are all raised/taught differently, some can ride both and prefer the steamage way, cool.
May even be true that for long distance, steady speed motorway cruising, it’s a no -brainer, just not my thing , I prefer to go the  “slow”  way, using the box and the go grip , music !

I even kept the original sub 5k miles perfect condition boat anchor.
A/ i case I buy a boat
B/ As door jam in tornado
C/ In the absolute belief that one day it’s value will be huge, someone will want to experience the thrill of steamtrain riding and the loopy he’s bought has completely fkd internal splines.