50mm bore on a stock crank

[vlatx]

Hi guys,can you put the 50mm JOG cylinder kit on a stock 40qmb engine,using a spacer and cuting down the cylinder from above to make proper compresion or you must use the stroker crank for it?

[benji]

I'm not an expert on this, but I'm pretty sure it won't fit without major work, if at all. I think the larger jog motors have a different stud pattern than the smaller jog Motors, also you'd need the crank for that cylinder.

[90GTVert]

The stroke on any of the cylinders intended for 90s is too long for a standard stroke crank and good results. If you want a really big piston, go all the way and cut the cases and install a stroker crank too. 90s and 50s have the same stud spacing. It's only different when you get to the 100cc like the BWS100 and such.

[vlatx]

I allredy have a strong HPC crank in it but only 39.3mm of stroke,the offer of stroker cranks in my contry are none.so im stuck olny with 47mm kits

['O'Verse]

Depending on how the cylinder and pistons made I guess. That's what I'm running right now. So it is possible. Malossi MHR 77 big bore 50mm bore on a RHQ 39.2mm stroke. www.rrd-preparation.com/en/kit-70-80cc-cylinder-piston-liquid-minarelli-horizontal/830-kit-77cc-50mm-malossi-mhr-big-bore-aluminium-axe-12mm-minarelli-horizontal-liquide-nitro-aerox-.html

[ryan_ott]

Most of the 77 cylinders are 50mm bore and stock stroke, you’ll have to check the rod length needed. But these are on the hyper race platform so they are different then the 90-100cc stroker cylinders and would require other supporting parts. I know TPR, Airsal and Malossi had the 77cc cylinders possibly others.

[ktb92]

I personally feel that you can definately get all the performance you could possible want with the 70cc bbk you have. Just gotta tune right and get the right upgrades. What kind of build you got? New to this forum btw, just trying to get some good conversations going. Im a certified scooter mechanic and really enjoy working on them and making them go fasttt.