CB550k1 US Import - UK registration

[Oddjob]

That looks correct, if it's fitted to the crankcase and thus pushing up against the clutch you won't get any more movement than that unless something is really wrong. The punch marks line up so that means it's in the right position. To get more movement you're going to need the cable attached.

[juitz]

Brilliant, thanks!

Maybe I'm been over cautious but I'm dreading having to split the cases cause I missed something.

[Oddjob]

The only thing I recall about the 550 clutch was telling people not to move the lever when the casing was off the engine as it would go past the fulcrum point and the internal lever used to over reach and you had to struggle to get it to go back into position without dismantling the mechanism.

[juitz]

I'm just lapping the valves but one of the valve seats has some slight pitting - this was cylinder that was corroded/seized.

I've lapped it once but hasn't really cleaned up the surface. More concerned about the pitting though.

[K2-K6]

I'd say that cylinder has had a ring let go at some point, given the imoact damage that's visible.

Looks like tge head would need to be skimmed also to reasonably establish proper sealing of head gasket etc.

The seats look damaged either from impact or fairly chunky corrosion effects.

[juitz]

This is wider shot - the pitting is just around the edge. I assume since the rest of the surface is ok the gasket should seal?

I've lapped it a few more timeswith fine grade lapping compound and it is cleaning up.

[Laverdaroo]

Dave if that looks like that there's history. If you're this far in another 40 quid to get it decked is a no brainer mate.You'll forever think about it and it's a point of potential niggle.
Surprisingly, on my heap, the head was in pretty fair nick, both inside and out and fiddling with straight edges revealed that I thought it was flat. You know, bits of glass to sit it on and feeler guages just to get an idea etc but had it done anyway as a guarentee. The machinist said he had to give it thress passes to get it spot on. Although it looked cock on, it just goes to show that after 40 odd years of use/neglect, things shift about and loose spec really easily. With yours having issues in the past, its 40 quid bud, annoying but get it done.


And it comes back all lovely and shiney................which is nice!

[Laverdaroo]

Mmmmm


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[K2-K6]

Maybe all right with the seats cleaning up (honda have tight tolerancing and angle, width etc of seat themselves) with some minor flow detriment, but not a serious worry on a road engine.

The head surface though is considerably more, ahem, agricultural than when it was made. It does look like someone has had an interpretive go at clearing it in the past.

I can't readily see a route to correct re-establishment of the surface other than a skim at this stage.

[McCabe-Thiele (Ted)]

If it was my cylinder head I would ask for the lightest possible skim to remove the marks.

[juitz]

Thanks, its what I thought.

I'll take to a local engineering shop to get it skimmed.

[juitz]

I guess the obvious question is, what is the maximu amount allowed to be skimmed?

I think around 1mm from some other posts?

[Bryanj]

Skimming the head is not too problematic but carefull with the block as skiming reduces the depth of the O ring grooves, which is actualy advantageous as head gaskets are thicker than they used to be so for standard blocks thicker O rings are needed.
You may find the valve timing very slightly out due to chain length

[Oddjob]

Skimming the head is not too problematic but carefull with the block as skiming reduces the depth of the O ring grooves, which is actualy advantageous as head gaskets are thicker than they used to be so for standard blocks thicker O rings are needed.
You may find the valve timing very slightly out due to chain length

It would be the block surely Bryan? the recess for the o-ring is in the block, the head has just a hole so skimming it would make no difference to the o-ring thickness.

[Bryanj]

Ken i did say carefull with the BLOCK