lightening a 6volt ducati flywheel

[scooterslag]

Yeah know its not the best solution but I've a SX200 thin taper crank in good condition which I want to use in a very mild 175 conversion (standard pipe, 22mm delly carb etc) Now I know the best logic would be to buy a GP crank for such a thing but sadly I can't afford to ( not made of money plus other commitments dictate) the LI/SX crank is prone to shearing off the odd taper but I've noticed a few peeps getting around this problem by lightening the flywheel. Now does anyone know the standard weight of a ally Ducati 6 volt SX flywheel, what would be a sensible minimum weight to reduce it by which isn't going to effect the tick over etc too much and who could do this job well? cheers Paul

[bristolmod]

before you do anything, ask yourself how many "thin taper" cranks have actually broken.

I've had scooters since 1968 and the only flywheel/ taper problem I've ever had was a flywheel on a TV200 which split along its taper due to excessive tightening. (air gun in a garage!!)

I know Innocenti revamped the flywheel set up on the GP range to counteract breakages, but with a mild 175 tune, I really don't think its going to be a problem in your case.

Also, beware of replacing good original Innocenti stuff for poor replacement stuff.......theres enough horror stories about poorly fitting parts to last a lifetime.

Lightening may be a good idea but you may sacrifice a smooth tick over due to lack of inertia.

Chris

[scooterslag]

Thanks for the information and your experience Chris, I've done quite a bit of research on here and the LCGB forum about li/sx crankshafts shearing at the taper. it seems about a 50/50 split to if the crank is suitable/unsuitable for the task- I was thinking about lightening the flywheel just to sit on the fence will probably run the crank and flywheel as the factory intended.cheers again Paul

[bristolmod]

no problem Paul.

FWIW I ran a TV175 S3 with a Muggy kit on original crank AND 6v points- never missed a beat and no problems.

If you do get the F/W lightened, please advise how it runs- may consider it myself.

Now- time for bedy byes!!

C

[warts]

If the crank has had a hard life then maybe it could be a problem.
Back in the day, I never heard of it happening - maybe to real racers, but not us street boys.
In '67 my SX had a 70mm bore and tune by A Francis in Watford. Only downside was the huge fuel consumption from the Wal Phillips "fuel injector".

[wack 63]

Easiest would be to get the brass centered Ducati flywheel and remove the fan then fit a nylon one, that's what we did in the 80's

[Muppet]

dont lighten the cast ducati dont fit a self destruct brass jobby

[scooterslag]

dont lighten the cast ducati dont fit a self destruct brass jobby

Ok so the ally and brass flywheels are a bit of a no-no, what would you recommend ?

[scooterslag]

If the crank has had a hard life then maybe it could be a problem.
Back in the day, I never heard of it happening - maybe to real racers, but not us street boys.
In '67 my SX had a 70mm bore and tune by A Francis in Watford. Only downside was the huge fuel consumption from the Wal Phillips "fuel injector".

The cranks no shiny NOS item, but had Al Diablo check it out a couple of years ago and he said it was fine, its looking like I'm probably going to run it as is. I've ran a smallframe vespa engine with a small taper (not the thicker PKXL taper) and a lightened flywheel and that helped with the problem of sheared tapers. I was hoping to do similar with the SX crank but not want to remove too much material that it either weakens the flywheel or causes erratic tick-over problems. What's the difference in weight between the standard ally Ducati 6 volt flywheel and the electronic flywheel (using a sx.li cam) ? a lot of people seem to use them on their engines and didn't know if there was a weight difference between them? Paul

[johnny LIS150]

there is a comprehensive article about flywheels and lightening in one of Mr B's articles . It gives weights and types of flywheel swopping around etc and replacing the fins with plastic etc .
Most damage on scoots and bikes is caused by over-tightening and heavyhandidness with aluminium .Some people just have no 'feel' with materials