Carrying on from my 1970 CT175 intro earlier 4 wks ago-
Previous owner said he siezed the engine, then put the bike away many years ago.  So I pulled the cylinder, saw some scuffing, but also found alot of oily/dirt around the crank (no fliter element)  Also some "ballsy" sound when kicked in neutral. I've rolled the bike around to confirm gearbox is intact, but I was hoping to start up and test the crank, gears, and clutch before doing anything.  But maybe best at this point to go for the full teardown?  Some very good posts on case spliting, crank pulling, etc, so thanks to those already who've already done this.
Anyone have a good machine shop for boring my cylinder? I'm ok shipping out the cylinder and crank assy.
Thanks for any comments or direction.
Joe M

Might be helpful to post where you are located

Hello - I am located in Santa Clara, CA (SF Bay Area).
Regards,
Joe Mulqueen
 

My own idea is to get it running first to see what you have. If its got oil in the trans & not water & if its got compression to feel on the kickstart then fire it up unless you have good reason to suspect its a bad idea. As i say--my idea but maybe not a good idea.

That's what I was thinking....but curious about the rumbling "ballsy" sound when engine is kicked through.  My little Honda CT70 Minitrail kicks through much quieter (maybe not the best comparison....).

So at this point, I'm leaning toward having a complete experiece with this engine but could definitiely use some Yamaha friendly machine shop recommendations.
Thanks,
Joe M
(in CA)

That's what I was thinking....but curious about the rumbling "ballsy" sound when engine is kicked through.  My little Honda CT70 Minitrail kicks through much quieter (maybe not the best comparison....).

So at this point, I'm leaning toward having a complete experiece with this engine but could definitiely use some Yamaha friendly machine shop recommendations.
Thanks,
Joe M
(in CA)

Oh, ok i should have read it better. Sounds like rusty main bearings & possibly bigend as that's in there too. I've had the rough sound very bad then settle down a bit with a very oily fuel mix so up to you. I'd probably run it but be ready to stop it if noise goes ferral!!. Your little honda is bathed in oil being a 4 stroke so unlikely to ever happen. What sounds bad to you might not be too bad for me for a test run.I did have a strange carry on--on my AT1 now a 175 top end where it sat for a very long time & had actualy stuck up with what sounded like rusty mains but was probably the piston coroded & stuck that stopped it turning. Came free & sounded concrete mixer on starting but settled down & been ok ever since. Not sure why it happened as hadn't washed it or got water in. I'd better run it tomorrow again--got me worried now lol.