Rebuild old 90?

[DaveyG]

I’ve got an old CT90 that has been in the family since long before I was born, and I’d kinda like to build it up into a restomod commuter bike. I want to keep the looks as close to stock as possible, but need some more power to cart my 200# butt up to say, 55mph without too much difficulty. The bike has a good bottom end but the top end is completely junk, sat outside for 10+ years with spark plug missing, piston rusted to the bore, valves are pretty much destroyed. My thoughts are this, Is it possible to get a bigger cylinder and head, that will work on the stock Honda 90 bottom end? Is the bore the only thing different between an old 90 vs newer ‘Lifan’ or what have you 125, 150, or even 160cc? I’ve found piston and cylinder kits for 150cc Lifan engines, as well as new assembled heads, what else might I need to make this work? New cam? Cam chain? Gaskets to fit the big bore top end? Thanks!

 

[motodevo]

Cheapest option is to bolt in a complete chinese engine. You may be able to use a chinese barrel and piston(if you find one with the same stud spacing, cylinder height, pistin deck height and piston pin size), but the ct90 has ignition points on the head (running off the cam itself) so a chinesr head wont allow the ignition to run. Even here in Aus where the ct90 and ct110 are plentiful (Auspost have used them as delivery bikes for decades) its os easier and cheaper to swap our the motor for a chinga if its lunched

 

[DaveyG]

Not possible to swap it to CDI?