Well I got the flywheel off the TYp250 mono. I want to lighten it for a more "modern" feel. Some have suggested take of "some" amount. Some have suggested take of the ring entirely.

Suggestions?

Try 8 to 14 ounces or most of the way through the `holes`. Taking the weight off completely is quite hard on the clutch and not as rideable. It is worth doing.

Try 8 to 14 ounces or most of the way through the `holes`. Taking the weight off completely is quite hard on the clutch and not as rideable. It is worth doing.

Something is amiss, according to my caclulations, the ring only weighs 8.3 oz. Anyone good with geometry care to double check my calculations? This is a mid 80s TY250 Mono, perhaps they had lighter flywheels?

Density 7.85g/cm3 0.00785 gr/mm3

Diameter 140 mm

Width 28 mm

Thickness 5 mm

Inner diameter 135 mm

Outer circle area 15393.35 mm2

Inner circle area 14313.45938 mm2

Area difference 1079.890625 mm2

Volume 30236.9375 mm3

Weight taken off 237.3599594 gr

Ounces 8.371685767 oz

Hi trialtrial, according to your weight width of 28mm the flywheel you have is fitted to the 'street' version of the ty250, as opposed to the weight width of 17.5mm that is fitted to the 'R' (competition) version. i have tried the 3 options of flywheel weight and much prefer all the weight removed on my standard engine.

Hi trialtrial, according to your weight width of 28mm the flywheel you have is fitted to the 'street' version of the ty250, as opposed to the weight width of 17.5mm that is fitted to the 'R' (competition) version. i have tried the 3 options of flywheel weight and much prefer all the weight removed on my standard engine.

60North - thanks for the info. Can I just remove the ring as a single piece? E.g. apply heat to the outer ring and press it off?

Edited December 28, 201114 yr by TrialTrial

Heat may cause the magnets to lose their magnetism

I have done a few on TY250 twinshocks which appear to use the same attachment technique for the band - I usually cut the band through with a hacksaw to release it without damaging the cup section or magnets

60North - thanks for the info. Can I just remove the ring as a single piece? E.g. apply heat to the outer ring and press it off?

hi, if you look closely on the ring you will see the timing mark line, you will have to decide how to transfer this to the flywheel, either with a center punch dot or what i did was when i cut off the ring with a hand hacksaw i just cut down the timing line till i was about 1mm from touching the flywheel then made a small mark on the inner end of flywheel with the saw blade, the remaining 1mm will break off by putting a thin bladed chisel or screwdriver in the end of the hacksaw cut and tap with a hammer. its not advisable to use heat on the flywheel due to it distorting or the magnets shattering. i have added a photo of my R flywheel on the right and the weight ring off my my spare flywheel on the left.

Thanks guys! Much appreciated. I will transfer the timing mark and then cut off the ring - I use coolant to ensure no heat damage.

I would of just pressed it off. Why would anyone ruin a part unless you have spares.

I have a 350, which may be totally different, but I trimmed half the ring. Much improved, expecially in overrunning where the momentum used to carry the bike way too far after shutting throttle, but also makes the vibrations and power pulses much more noticeable. I would machine half of it and see if you like it. You can always take off more, but hard to put it back.

kcj