1971 cb350 rebuild checklist

[moewillis]

a little background:

bought a running cb350 for $600 with a title. had a bad battery. replaced the bad battery and it fired right up and seemed to run fairly well. revved it up to about 6k sounded good. started to see oil coming out of the exhaust. shut it down and pulled the plug and saw a bunch of crap on top of the piston. (great). went and rented a compression tester. 60 psi on one cylinder and about 100-105 psi on the other (cold) so i am assuming it's in need of a rebuild (with only 7266 on the clock).

obviously i need piston rings (will be slightly boring it out) and a gasket set.

what else do i need?

what do you guys usually bore out to on a simple rebuild?

please all input and tips appreciated as this will be my first rebuild

clymer manual already ordered

 

[Sonreir]

Honda usually offers OEM pistons and rings in .25mm increments.

Before going for the bore, check the valves as it's a lot easier to do. Get the head off and pour some acetone into each of the intake and exhaust valves and let it sit for a few minutes. No acetone should leak through to the combustion chamber.

If everything checks out OK on the valves, then pull the cylinder jug and pistons. Sometimes you can get away with a re-honing and not need a bore, but get a machinist to look it over.

 

[Sonreir]

Also, make sure you're running your compression check with the throttle open. It's an important step a lot of people miss.

 

[moewillis]

ya i had the filters and housings off, choke open and throttle wide open checked each side three different times with the same results. cant believe it was running so well with the rings being trashed. took off headers and had oil on the outlets and on spark plugs.

not going for hopping it up just want it to be as close to "good as new" as i can get it so if i dont need to bore it out even better. will be cleaning the piss out of everything i touch.

so is there even a slight chance that the OE size rings could do the trick?

anyone have any idea what to look for price-wise on a hone/bore job?

should i get the new piston/ring set or just rings if pistons look okay?

should i be replacing the cam chain as well? tensioner?

 

[Sonreir]

I just got quoted $160 for bore and hone.

If you change out just the rings, you'll still want to get the cylinders honed, though. It'll help the new rings seat in a lot better. Also, make sure you don't use synthetic oil, afterward.

As far as cam chain and tensioner goes, you'll need to get someone else's opinion on that topic. Easy answer is new parts never hurt.