Tuned standard cylinder

[mijapxman]

My mate brought this for me to size a piston and possibly further tune for him. Bore looks very good. Fin on top of cylinder missing, Cylinder head looks fine, could be done better.

Will try to take some measurements in next few days. 👇try checking the original listing link 😉

www.ebay.co.uk/itm/Vespa-Px200-Tunned-skimmed-Barrel-And-Head-As-Shown/303134636741?hash=item46943b7ac5:g:JvkAAOSwIz5cwIdp&redirect=mobile


Mij☺

[mijapxman]

Measured this cylinder today, a tad on the peaky side 😉.

Transfers 123°

Exhaust 185°

Blowdown 31°

Seems it will need an expansion exhaust, a thin ringed piston at least and probably 😉 a gearing change.

The exhaust porting looks well done ,is flat at the top for the same length as the transfer ports.

Haven't checked the bore size yet and haven't tried fitting it to his engine yet, to measure the cylinder head squish.

Mij☺

[boomshakalak]

Currently messing with a standard BGM 200 top end myself at the minute, a bit of mild O-tuning.

That`s big exhaust timing there at 185

I found these cheap thin ring pistons, I have one to play with, they`re advertised wrong and are actually 66.5mm standard size, if you wanted to try the barrel out.

www.ebay.co.uk/itm/67-00mm-200cc-SCOOTERING-WORLD-PISTON-KIT-FOR-VESPA-SCOOTERS-1-5mm-RINGS/392159224726?hash=item5b4e82e396:g:T4AAAOSwl3xb1GuX

[mijapxman]

Boomshakalak,thanks for the reply. Sure is big, will have to wait and see if I can get it down, using a smaller base gasket ,but don't have my mates engine yet, to do some engine specific measurements with my Buzzwangle 😉

scooterlab.uk/the-patented-buzzwangle-a-new-tool-to-help-with-scooter-timing-news/

Those pistons are ok, I've used them in four 'O tunes' using 120/174 timings and they are all going strong. The pistons I've used are on the heavy side, but obviously get lighter than they were as you port them. The ones I've seen are a slightly taller too.

Can't remember if they are the same as the pistons Beedspeed  sell for more money, but they work well too, in an 'O tune '.

beedspeed.com/collections/vespa-pistons/products/vespa-piston-kit-p200e-efl-disc-rally-competition-o-s



Mij☺

[mijapxman]

Just found this👇 about the above Beedspeed pistons, very interesting 😉

www.scooterotica.org/forum/viewtopic.php?f=8&t=40387

Mij☺