Aug 2, 2003
i have heard that you can take a stock z50 and put a xr 70 or xr75 head and piston on it and it will bolt on and run. is this true or what can u do to make it work? also what is the cheapest way to get more power from a z50? id like to bore up to around 80cc unless there is a cheaper way to go bigger.. doubtful.


Too much of a good thing.
Nov 22, 2000
An XR70 head will physically bolt up to a Z50 engine, but an XR75 head will not.

There is a compression ratio issue with the Z50/XR70 head swap though.

Your best bet is to buy a Kitaco or Takegawa kit that includes a piston, cylinder, cam, and carb, and use your stock head. The big bore piston/cylinder alone will make a noticeable difference for cheap.


Sponsoring Member
Nov 27, 2001
you can take the xr70 cylinder and head and directly bolt it on the z50. same bottom end. You might have to clearance the case a bit. sometimes they are a bit tight around the base of the cylinder.
there is no real advantage to just the head other than the bigger valves. Also you'll want a bigger carb for the bike to breath. Also the pipe is a limiter. But if you have access to the cylinder AND head from an xR70 then go for it. MUCH cheaper than takagawa. These parts are readily availible from used auction pages. But for serious HP the 80+cc kits are the way to go. You will need to get different cams, valves, carbs... just how much do you want to spend????
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