Topic: Honda cb750 k2 cam and bearing issue

[topperharley]

Hi from finland!

First sorry about my english.
You can see in the picture there is some marks on the bearing surface. In the bed and cam.
Should i get these surfaces machined or can these bearings still be driveable?

Any experience or appinions?

[topperharley]

So i went to a local motor workshop and the expert said that give it a good clean up. Clear all the edges and try it on. If the cam rotates smoothly no prob.
Thats what im about to do because getting it machined is really expencive. So thumbs up and hard driving.

[754]

Looks like you caught it early..may.clean up.
 How do the rockers look.
 
The picture shows what happens if you keep running it.

[70CB750]

How deep is it, Topper?

[topperharley]

i know it looks pretty bad but the workshops price was around 700$(640€) and do not have that kind of money to put on repair.
Rockers are fine and cam too. The mark on bearing surface aint really as deep as its looks. You can just feel it with your fingernail.
I think i have to just trust what the workshop guy said and give it a polish and keep my fingers crossed.

_Anyway i was like wtf when i looked at the pistons. Engine is bored to 900cc I had know idea.
I have to buy new piston rings and head gasget. Piston diameter is 67mm.
Do you guys have any good tips where to find piston ring set and head gasget?

Thanks a mil. J

[70CB750]

There is a bunch of sources in USA, but hopefully somebody from your side of the puddle pitches in.

http://www.cyclexchange.net/

http://4into1.com/

http://www.cb750supply.com/

[Bodi]

Clean used cam towers would cost a lot less. the loading on these "bearings" is low - otherwise Honda would not have run a steel shaft in a plain AL alloy "bearing". It's possible but difficult to install bronze bushings, I saw this once but don't know how it worked out. Only the lower side gets any loading - the cap surfaces are probably like new.
As long as the top end oiling is working correctly you should not have any problems with just cleaning them up a bit. A fine stone over the cam journals by hand and minimal cleanup on the towers. You don't want to remove any appreciable amount of metal from either.
If piston rings are difficult to find from the usual sources they can sometimes be sourced from ring manufacturers: the engine shop I use has managed to get rings for some very rare old engines that way. Not as cheap as stocked sizes but anything can be made to order.

[topperharley]

Thanks! Dynamite answers at the speed of light

[754]

That is a Henry Abe 900cc piston may be hard to get rings.

[topperharley]

Oh and i did sent mail to alias PeWe who had same problems.

[BPellerine]

rings are 195.00us for a set of four from total seal,they only do full sets,bill

[MCRider]

rings are 195.00us for a set of four from total seal,they only do full sets,bill

That's where Mike got mine to re-ring my Arias 67mm pistons.  No smoke, seems to have broken in well.  WE used the "hard" method.

"...to find piston ring set and head gasget?..."  Head gasket from "Cometic".

Point of order.  67mm = 889cc