Rebuilding Cb350: Piston kit/ gasket kit (questions)

[blake57]

Rebuilding the 1971 cb350:

Okay so Gasket kits:

Ones to avoid?
Whats the best for a rebuild?

Piston rings? I dont have much money to spend on stuff should i reuse my pistons or upgrade to wiseco? Im pretty sure im on my original bore so i think i can get STD rings... whats a good price for STD rings and whats the the kits to stay away from?

 

[PePe]

I might be able to help you out. When I get back in town tonight I'll check my inventory. Gaskets I'd say use Athena they are the best IMO. As for rings, did you check your compression to see what it is? I can PM you prices tonight

 

[AlphaDogChoppers]

Given your budget constraints...

If the pistons and cylinders are in good condition, re-use the pistons.

Don't consider re-using the rings. ALWAYS put in new rings when an engine is torn down. You wouldn't want to waste a gasket set putting an engine together with old rings.

 

[blake57]

I might be able to help you out. When I get back in town tonight I'll check my inventory. Gaskets I'd say use Athena they are the best IMO. As for rings, did you check your compression to see what it is? I can PM you prices tonight

my compression was 170 on each cylinder so im good. Standard bore i think... only 10000 miles on the bike.
i cant use my rings because i broke them taking them off plus i was gonna replace the rings anyway... i was just asking is it dumb to do STD rings? should i bore to .25 and spend the money on the wiseco will it be better? ?

 

[AlphaDogChoppers]

Stick with standard. There is no point in boring out an unworn cylinder.

 

[djelliott]

Check Cycle Exchange. I think they have a good gasket set for the 350. DO NOT get the ones from Sirus. I used them and they are shit.

 

[blake57]

Check Cycle Exchange. I think they have a good gasket set for the 350. DO NOT get the ones from Sirus. I used them and they are shit.

Thanks man!

Stick with standard. There is no point in boring out an unworn cylinder.

Im going to borrow my friends bore gauge and micrometer to check the clearance just to double check.
whats tolerable clearance? im at school right now i cant access my manual.

 

[AlphaDogChoppers]

You can assume the cylinder is not worn if there is no ridge at the top and no damage that you can see.

A ridge of about 1/2 thousandths, you can feel with your fingernail, but not your fingertip. A ridge of 1 thousandth you can feel with your fingertip.

I don't know what acceptable piston clearance is. I don't have a manual for that engine yet.

 

[djelliott]

From the manual:

BORE

Standard value- 64.01mm~64.02mm

Replace if over- 64.11mm

TAPER

.005mm replace if over .005mm

OUT OF ROUND

.005mm replace if over .005mm

 

[Wee Todd]

new rings as mentoned,don't forget to hone to bores,,,,,or banjo hone them(fine grade emery paper),,,you have to seat the rings,,,,,,,,,

 

[surffly]

There is more to how and engine is wareing then just what the compression numbers read.

Often i see motors that have to high of a compression reading due to build up on pistons and what not. this can mask a loss of compression around the rings.
also just a "standard" compression test isnt everything that needs to be done. really should do a proper leak down before opening up the motor.

Have you "mic'ed" up the motor to know what the measurements are and checked the clearances against the factory manual?
again just looking/feeling isnt enough to know what the whole story is.
not worth it to tare it apart and address nothing and put it back together. you need to know for sure whats going on.

while people claim that these are super simple motors and some even liken them to working on lawn mowers, remember one thing....
alot of these motors are more give or take 100hp/L with some nice tech for the day....