XR50 engine rebuild

[Bill Wright]

I am rebuilding my sons XR50 motor and was wondering if anyone new of an online service manual.

Or, if anyone knows how to set the timing correctly and what tork the nuts to mount the head should be torqued to?

 

[s.d.duner]

i havent found any online services that offer info for free. They all want you to buy a manual from them.

Go to your local dealer and either buy a service manual or just ask an employee for the torque specs. (one that fixes the bikes, Not the salesman).
It's a popular bike so they may know it in their head

 

[biglou]

I tell you, I didn't use a torque wrench when I did my rebuild (82cc big bore kit). I used a 1/4" drive ratchet and just tightened the four acorn nuts in a criss-cross pattern, getting progressively tighter, and staying close to the head of the ratchet. One hand only!

As for the timing, check out the two pictures below. One shows the timing mark on the flywheel relative to the case, the other shows the mark on the cam gear in relation to the mark on the head. Note that the rockers should be loose (valves closed). It's pretty hard to screw up. I did it correctly first try.

Flywheel mark
Cam gear mark