4 hours ago, thai-ty said:

the cranks/flywheels are ridiculously heavy in Yamaha 250/350 motors.

Funny you say that,I'm thinking of adding more weight to my Ty250 flywheel, I rarely use it and find it too easy to stall - I ride without the clutch if at all possible. It just doesn't have AJS flywheels !

What model ( A B C.. ) of TY is your flywheel from John, the B model flywheel is heavier than he rest of the model.

Guy

36 minutes ago, guy53 said:

What model ( A B C.. ) of TY is your flywheel from John, the B model flywheel is heavier than he rest of the model.

Guy

Hi Guy, I think its most likely a D model, but its built up out of junk basically. The bike was a non runner from a breakers yard and I built the engine from boxes of bits that contained about 3 incomplete engines... What I was thinking of doing is to turn up a new band on the lathe as heavy as I could fit in,and gradually trim it down until I like it.I think maybe I'm expecting too much from it really,but it will be interesting to see what happens.

Here is a picture of a B model ( here in Canada )

Guy

From memory that looks the same as the one I'm running. I'm actually going to ride a trial on it on Sunday,maybe I'll take the cover off after that and have a measure up,see what will fit.

John, if I can get to the part, I'll measure the thickness and the with of the band this weekend.

Guy

Jon you can fit in a much larger weight band than the one in Guy's photo. I'm working on a 360cc TY250 motor at the moment and it has a weight band that is at least twice as heavy as the one in Guy's photo. People tell me that the weight band on this 360cc motor looks like what was fitted to the 320 Majesty motor. The owner of the 360cc TY250 I'm working on told me that the huge weight band flywheel was fitted to his Yamaha factory supported TY250 in 1975 at the same time as the Yamaha fuel injection was fitted, to tame the motor down. The super-heavy flywheel was then fitted to this 1977 TY250 motor when it was converted to 360cc (in 1977). I'll post up a photo of the flywheel soon.

Edited November 23, 20196 yr by feetupfun

I've never understood this obsession with getting rid of flywheel weight.

Whilst no expert on the mechanics of bikes, I assume this new fad is to do with the new / modern... classic sections, where you need quick zippy power.

 

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After riding the Bath Classic trial on Sunday I'm having second thoughts.Once I got used to how it rides again I got on really well with it and enjoyed the 2 stroke zap - Which was just what was needed for the A route of the Bath trial.I think the problem is that I so rarely ride it,even my little James is more like a 4 stroke with its huge brass flywheel, the BSA and AJS both plonk superbly which suits how I generally ride. So because there are so many other projects in the workshop I've decided to leave it how Yamaha and Mick designed it back 40 years ago. Just make sure I do some practicing on it before I use it for another trial.

9 hours ago, metisse said:

Whilst no expert on the mechanics of bikes, I assume this new fad is to do with the new / modern... classic sections, where you need quick zippy power.

 

 

I believe in moderation in everything, including flywheels.