A couple of questions,  The crankshaft assembly in my CT1-B is a little corroded but still very smooth, and I'm not sure if that's going to be a problem.  It turns very freely, I'm just not sure if the surface needs to be pristine.  Also, I'm putting in a new piston, and replaced the bearing and upper needle bearing.  Do I need to grease the needle bearing before installing it?  Also, should I put a thin film of oil in the cylinder head when installing it or just install with it good and clean?  Thanks for your help in advance.
 

Hello,

The outer crank surface we are looking at in your good photo does not have to be pristine.  It looks like most I have uncovered.

Yes, it is a required routine to lightly oil (not grease)  the bearing and cylinder/piston surfaces as you assemble them.  I use Marvel Mystery oil, just one of my quirks, being an Old Fart mechanic.   Always worked for me, even in my high performance engines.    

Also, before you button it up, drop a few drops of oil on the lower (big end) crank bearing, and also a few in the holes I am pointing to in the photo. 

 

Thank you! Will do.

It would probably be counter productive if you tried anything abrasive for instance because everything you got off would make it's way downward.
Maybe just try Marv . Just wipe it on and let it sit for a while then wipe it off and swill the case out .
I have used Marv on a place that i worked . It's good gear . I think it would get rid of some of the staining from old fuel.
Or just leave it as stated above.

Remember, like you said, "lightly" oil the surfaces. Just a few drops, thats all that is needed. A light film.

Hope your assembly goes well !

Yep agree with above comments & can't add anything--so i'll shutup lol. Love CT1's. Had one in about 1990-ish & had a--modified to fit--MX175 exhaust which about doubled the power as my ride to work bike. Sold it to the girl next door who used to carry her dog called "hedgehog" on the tank & recon it would show 70mph flat stick with headgehog dribbling everywhere in the wind haha. True story. Even funnier when she was calling the dog at night at the top of her voice if he went wandering. Bit like the cat on the otherside called 'bike shop', found in their cycle shop. Hedgehog/Bikeshop in the evening. Lucky we're semi in the country or probably all get taken away by men in white coats. Now-- gotta track down my old CT1. Oh, & had a girl with a Yamy YL1, customer at work, & always came in with her little dog in a back pack with a hollowed out tennis ball for a helmet.

Great story !
The only thing better than a sweet vintage bike is a sweet vintage bike with an exceptional story behind it.  

What does the other half of the crank look like? 

If the big end rod bearing got rusty at all it won't last long.  You won't be able to see the bearing itself but if there's rust in the area it's sometimes better to fix it now. 

Got that right !!