Honda 400/4 camshaft design is it normal?

[McCabe-Thiele (Ted)]

I was a little surprised to find that the camshaft does not have replaceable bearings as it appears to run directly in the alloy head & camshaft cover. Fortunately my bearing surfaces look good. If needed how do you repair the worn housings?

[AshimotoK0]

I was a little surprised to find that the camshaft does not have replaceable bearings as it appears to run directly in the alloy head & camshaft cover. Fortunately my bearing surfaces look good. If needed how do you repair the worn housings?

You get a replacement head and cam cover. There was a project bike in Cassic Bike magazine that had been modified to use shell bearings off a Villiers industria engine but an extremely tricky maching operation to fit them I imagine..

discussed here:

http://www.sohc.co.uk/index.php/topic,7175.0.html

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[McCabe-Thiele (Ted)]

Wow that sounds expensive to buy a head & cam cover. On my old 850 A series engine you could get the block line bored and later bearings fitted.

[AshimotoK0]

Wow that sounds expensive to buy a head & cam cover. On my old 850 A series engine you could get the block line bored and later bearings fitted.

Quite often the cam cover is OK and the scoring is only in the head. Agree pretty expensive to fix,  so rule no.1 ... change oil regularly. Worst model for this happening is the CB250/360G5 IMHO.

[Nurse Julie]

The cam cover bearing surfaces are usually fine. It's the cam chain pulling the cam downwards that causes the problem to the head.

[McCabe-Thiele (Ted)]

The cam cover bearing surfaces are usually fine. It's the cam chain pulling the cam downwards that causes the problem to the head.

Yeah I had thought about that plus the valve springs pushing back on the camshaft.

[Bryanj]

As long as oil and filter changed every 1500 miles they will last 100's of 1000 of miles

[philward]

I converted a 750 cam carrier (different design to the 400 I know) in the late 80's -used shells on bottom and new caps that held lowere shells in place then line bored, I did work at BAE system though so had access to the right machinery