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lightened flywheel on an eldo?

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cliffrod:

--- Quote from: guzzisteve on February 12, 2026, 08:12:24 AM ---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

--- End quote ---

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.

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