CB350 top end rebuild questions

[TDC]

Last fall the cam in my 350 roached out on me. It wiped out one of the end bearings and the lobes and rockers on the left side. Since then I got a second motor with the plan to swap the top ends. After opening it up I found one tip of a rocker arm to have quite a bit of pitting.

One question I have is can I take a known good rocker from my bad motor to replace the suspect rocker? I guess I'm not sure if mixing and matching parts is a bad thing or not. I would hate to have to send just one in for reconditioning let alone all of them $$$.

The other question is would it be ok to just hone the cylinders and get a set of standard rings?

Josh

Also: I know it sounds weird but does anyone make lower compression pistons for a 350? I have an idea for a future project.

 

[Wee Todd]

Lower compression pistons?????????? save the turbo for another day and the super charger.,..want to go fast,,,,,,install gpz.pistons(66mm) kz 750 pistons,,,,,,,,,,,kz 450 slugs are the best(67,5 mm)if you can find them

 

[DrJ]

Last fall the cam in my 350 roached out on me. It wiped out one of the end bearings and the lobes and rockers on the left side. Since then I got a second motor with the plan to swap the top ends. After opening it up I found one tip of a rocker arm to have quite a bit of pitting.

One question I have is can I take a known good rocker from my bad motor to replace the suspect rocker? I guess I'm not sure if mixing and matching parts is a bad thing or not. I would hate to have to send just one in for reconditioning let alone all of them $$$.

The other question is would it be ok to just hone the cylinders and get a set of standard rings?

If it's only the small end of the rocker that's pitted, it's no big deal. That end just bounces off the valve. You can grind it down and polish it yourself if you want, just don't grind it down too much. I've mixed up rockers from different engines and didn't notice any problems. You might want to weigh them to check if they are all close to the same weight. Yes, if the cylinders are not too worn you can get away with just a hone and a new set of standard rings. Just need to check the ring gaps to see if they are within spec. The CB350 is a very robust motor and can take a lot of abuse and they're easy to build.

 

[TDC]

Thanks Dr J. I'll check if the matching one is actually good or not.

Josh

 

[jcelicae]

how'd you get your cam chain off?

 

[DrJ]

how'd you get your cam chain off?

It's not necessary to break the camchain on a CB350 to disassemble the top end. Just remove the 2 camchain sprocket bolts and slide the cam through the side with the lobe profile cutouts. You'll need to rotate the cam to line up the lobes to do this. Make sure to tie a wire to the sprocket and chain to prevent them from dropping down to the crankcase.

 

[jcelicae]

that's what i figured. i was working on doing that the other day and the cam turned and my wrench got stuck. stupid mistake. took a while to get out AND a buddy.

 

[Swagger]

'Charge that puppy just to rub thier noses in it!

You cna always have the rockers hardfaced and reground but as the good Dr. says, mix away!