Motorcycle Repair: ct110 cam timing & chain tension, chain tension, ct90

Question
I've skipped the timing chain on my 81 CT110 and am unsure on retiming the cam and retensioning the chain. Are these engines an interferance motor (do the valves hit). Can i swap a 1977 ct90 head onto a 110? Which cam should I use

Answer
Gavin, I'd recommend you find a manual if you aren't familiar with small engine repair but it you want to tackle it without a manual...you'll find a T stamped on the flywheel.  THis is top dead center.  You will also find a 0 stamped on the cam gear.  There will be an indicator mark in the cam cover bore or two cast taps in that same bore.  With the crankshaft on TDC aline the 0 with the indicator in the cam cover bore hole.  Once you put the cam bolts back in the crank and cam will be timed.

Depending on how many teeth the camchain skipped, you could have bent the valves.  According to the part numbers, a CT90 head is different than a 110.  I'm not sure if it will work or not. They are certainly very similar and would probably bolt on.  You can use either cam but if you use the CT90 head and valves, use that cam.