Flywheel weights experiment

[olliewtf]

After my vespa converted flywheel sheared (which I believed to be around 2kg) I bought a little used Sil flywheel off a user here just to get me back on the road.
However, I was concerned about the weight. Its the heavy one at 2.6kg.
Since fitting Ive noticed a few pros and cons. Low down tractability has been transformed; it ticks over alot easier, and its easier to roll on the throttle, whereas before if i rolled on it would sometimes bog a bit (still getting jetting right too, but i believe this is down to lack of inertia plus rich jetting whilst out of the power).
The cons: throttle pickup is non existent, very much like a standard engine. you just roll and it does its own thing.
Another con is more of a fault; since fitting it doesnt like to rev out. symptoms are similar to rich or even really lean main jet. it bogs and wont pull. I know the stator was fine and cdi before just changing flywheel. Need to investigate that one.

The reason I say the above is that Im in a unique position to experiment with weight. I dont like the 2.6 due to the stress it could put on the crank, so I will sacrifice its low down benefits. It also doesnt suit how i tuned my top end; I need something that can spin up quicker so i can throw back the throttle, let the clutch half way and rag it from the lights (and burn all my plates in the process)

Now mid weight is 2kg. AF super light is 1.4 I think? In the future I would like to maybe fit a reed valve, so will push the already fairly high exh timing further and extend blow down a touch. therefore it will want to rev. (I may need to rethink my clutch but its held pretty well so far)

I know the AF super light can be a b@5t@rd to get to tickover. I dont want something i have to forever blip to keep alive. Having said that it struggled on tickover at 2kg.

So Im thinking of going for 1.8 or 1.7 to find a good middle ground between the two.


Has anyone else got some experience of playing with weights? particularly non standard weights? Id like to hear your experiences and what weights you run, always in relation to your set up.

Much obliged!

[Yanker]

Hi. Never had the tick=over problems you describe and have used all weights (my pref=the 'mid' 1.8 kg)

Suggest your missfire issue is to do with pick-up missalignment with the trigger on the current flywheel.

(Trying to kewp it a simple logical diagnosis work through here).

[olliewtf]

cheers yanker.

I was thinking the same re pickup alignment. Annoying though as height is same as another stator I had, and both have worked (just not with this flywheel. suppose there in lies the answer.)

The tickover thing is not so much of an issue that can't be worked around, but I have noticed a difference.

May aim for 1.8kg but would be interested to hear from people who have used a af light flywheel and a different weight flywheel on the same engine.

cheers!

[Muttley McLadd]

May aim for 1.8kg but would be interested to hear from people who have used a af light flywheel and a different weight flywheel on the same engine.

I've used an AF light one, and then a 2kg Indion one (from Beedspeed) on the same engine. GT186 with RS44 and a 30 mil delorto.

It went much better with the 2kg one on it. Went up hills without changing down, and could be ridden two up. No visible difference to the pick up, or the fuel economy

Edit.. also tried an AF one (standard weight - real one) and a lightened one - 1kg with a plastic fan - on an RS185. The light one was shit. Couldn't pull off without revving the tits off it, and it wouldn't go up hills. The hill outside our house, that you'd normally whip up in second and third was first gear all the way. The stock AF one was better.