head from a 1P39FMB, fit on a honda xr50 botton horizontal/cd50

Does anyone know if a head from a lazer 5. 1P39FMB , will fit on a honda xr 50 botton end 50cc horizontal/cd50 engine. The honda has very small ports and i wanted to replace it with the 1P39FMB head but it has a vaccum line. any one know if it will work? Thanks

It'll probably fit, but you can fit at least 47 mm piston, corresponding cylinder and head with much bigger ports and valves.

Would that be a 1P47FMD cyl. Could i use the. 1P39FMB Head with the 47mm cyl. What do i do with the vaccum line. Thanks

Yes, 47 mm cylinder can be used with the 39 mm head. but you must to fit piston with the flat head. Those you can find among performance parts for Chinese clones of "Honda" GY-6 scooter engine, marked as 139 QMB. Basically, all those performance kits for scooters with 47 mm head are marketed as 80 cc kits.

Here is the pic:

http://www.scooterdigest.ru/photos/4109/5.jpg

On the left - scooter piston, and on the right - standard 47 mm piston for "Honda's" horizontal engine. As you can see, piston skirt is shorter on a scooter piston, consequently - piston is lighter than stock one, so engine would run more... lively.

But still, I would go to to head swap, because... See for yourself - https://88.img.avito.st/1280x960/1685683488.jpg . On the left is standard 50 cc head, and on the right - standard 72 cc head. Bigger valves, bigger ports, and as a result you'll squeeze few extra ponies from your engine.

Ant there is "Plan C" - splitting crankcase, crankcase-cylinder-piston-head swap and you'll get 107 cc engine for pocket money.

so the gy6 cylinder and head work with honda xr50 bottom ? . can i use this kit?

http://www.ebay.com/itm/80CC-BIG-BOR...9Urb1W&vxp=mtr

No, no... You'll need just this piston. You can buy it separately, but before you order it, check with the seller is piston's pin and compression height same as on your stock piston. And buy one or two extra gaskets between crankcase and cylinder, in case you hear some ticking sound while this upgraded engine runs (piston slightly hits the engine head). By adding extra gasket, this (potential) ticking sound will stop.

But again, I would, together with 47 mm piston and cylinder, fit corresponding head. In this case, you'll need standard 47 mm piston (ordinary comes together with the cylinder), because its combustion chamber is bigger so aforementioned GY-6 flat head piston can't provide enough compression ratio, and subsequently - max power drops.