What I have here is a very unique engine configuration from a Japanese Domestic 90cc(88) CL90. In Japan they were 89cc, in the USA 99 cc.
Some background about 10 years ago, a good friend who is an officer of the Vintage Japanese Motorcycle Club. He is a meticulous restorer and he had a proposition , He wanted a Honda CL175K3 in Orange Model that I had available. He was willing to swap his restored Japanese Domestic CL90 for my model. In his restoration, he had changed the Japanese 88cc cylinder and head combination to the US specification 100cc(99) model. In the trade he gave me the 88cc changeover parts. They all appear to be in good condition.
So pictured is the cylinder which the inside is very smooth, the Cylinder Head,(no valves) Included is a brand new piston, and two sets of rings. Both sets are new, one box is stamped 13021-107-004, which shows for Honda 100cc. the other box the number can't be read. I do not know whether these pistons can be used with this cylinder Please investigate for yourself whether they can be used in this 89cc cylinder .
So anyone with a domestic CB or CL100 that needs a new upper end--this is a really good start. You will just lose the slightest amount of displacement.