You are here:

Motorcycle Repair/CT70 restoration


CT70 rebuild
CT70 rebuild  
I purchased what I thought was a 1971 CT70 engine that needed an overhaul. Crankshaft was severely rusted on the left side of the case. I replaced it with what I was told was a CT70 crankshaft. After installation of all new bearings including thrust, I oversized the cylinder .75, fully reconditioned the head and installed. Then I went to complete the install of the cam chain and found out that the original flywheel Inside Diameter is smaller that the new crankshaft dia. The original flywheel I took (that does fit the original shaft) is a Hitachi 120. The technical question I have is: does the Mitsubishi flywheel have a larger ID flywheel? Could this be for the 1972 model and if so, is the wiring harness compatible.
Thanks. Brooks

Brooks, I am in the hospital until tomorrow so don't have all my resources at hand. Honda used more than one manufacturer for their electrical components at times.
You would have to match the rotor and stator in that case.
Also, there were both manual and automatic transmissions used on the early models, which use a different crankshaft I think.
Bill Silver

The wiring harness connectors should be the same, but check the part numbers on-line or at a Honda dealer. I don't have specifics on magneto sizes but there are numerous sites that specialize in Mini-Trail models.

Motorcycle Repair

All Answers

Answers by Expert:

Ask Experts


Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

©2017 All rights reserved.