Aluminum atc90 cyl. ?

[czlou]

I picked up a atc 90 motor this weekend and it has a aluminum cyl. on it. It has 89cc cast on it. Does anyone know if it is a early 90 motor or a aftermarket cyl. ? it has a 13mm bolt for the cam chain roller, not the 10mm bolt like the rest of the motors i have? czlou

[shortline10]

Sounds like a 1960's motor .

[czlou]

anyone have any thoughts on the cly. being aluminum? czlou

[shortline10]

anyone have any thoughts on the cly. being aluminum? czlou

Old 1960's s90 trail bike factory alum cylinder . Whats the serial # on the block ?

[czlou]

atc90e sorry, i didnt know about ct/sl 90 alum. cly's in the 60's. Do they fit right on or do you have to machine them to fit? was this a trick setup for the day? the motor has a few goodies on it. czlou

[greenhuman]

You have to match that alloy Honda cylinder to a road 90 head or it will leak oil around the oil gallery at the stud.
It is to do with the positioning of the O ring. With the ATC cylinder the O ring is in the cylinder and the road version has the O ring in the head. You can modify a couple of O rings to make an extra long O ring but it is trial and error and a real pain in the rear end.

[czlou]

Thanks for the info. I havent taken the motor apart yet. I will be sure to take a good look at the o'ring and head. Always good info on the site. czlou