50mm piston

[Rocketdog]

Just out of curiosity, and I need to know for a project. Have any of ya'll weighted a 50mm BBK piston before. The standard 47mm dished type weights 63 grams w/rings. If your interested.

RD

[90GTVert]

Luckily my engine blew up a few days ago, so I just happen to have a 50mm piston lying around. lol I have cut the valve reliefs a little, so weight will be slightly off of a box stock piston. My NCY 50mm piston w/rings weighs 76.7g. I dug the 39mm piston out and it weighs 43.3g.

[Rebel]

have you seen the thread that Mougeot started, and the photos of his oil mod for pistons? He drilled a few holes in the side skirts of the piston to allow for better oiling, might have lightened the piston just a hair with that.

scooterrebels.proboards.com/index.cgi?board=125plus&action=display&thread=1009

[Rocketdog]

Thanks GT. That helps a good deal. Sorry to hear about your mishap with the scooter though.

I saw it Rebel, but forgot about it. More good info. Thanks.

RD

[Rebel]

Ya, I went brain dead, you posted on that thread.

I'm wondering if there would be a gain of any power with that mod. Better oiling would reduce some friction. A even slightly lighter piston might be more responsive. But then it might not be enough to make any real difference.

[Rocketdog]

Kinda depends, I think. Does the stock setup splash enough oil on the cylinder walls? If so, is it as effective on a larger bore? Some splash systems work pretty well, others are iffy. Are the oil rings getting more than they can handle?

I do think that lightening the piston on a BBK is a good idea. At least if you don't get lighter than the stock 49cc piston. It might be too light to balance well. The opposite is why I wanted to know what the 50mm big bore piston weighted. I have a 47mm piston I want to try out for compression reasons and didn't want to get heavier than the 50mm one. The more towards the 47mm stock BB one the better, I think.

RD