CB500 K1 rocker cover woes

[Kai.chris]

Just started to clean up my rocker cover. Noticed inside the bores that hold the rocker pins looks like Swiss cheese in a few places.
Is the cover scrap?

[McCabe-Thiele (Ted)]

Looks like lack of oil has done that damage I'm no expert, my Dad used to call it bearing pick up.

[Kai.chris]

Thanks for your reply.
I was thinking the same, or it was a poor quality casting to begin with.
Just spent 4 hours polishing the top of the bloody thing as well  :'(

[Bryanj]

If they are still circular and rocker shafts fit snugly theywill be ok to run, probably standing corrosion and only a small percentage of bearing area

[Murf]

The rocker shafts are not supposed to revolve in their housings so were not designed to have lubrication, the rockers move on the shafts.  Unfortunately on the early bikes K0 K1, the shafts were prone to revolving causing the housings to become oval. Which basically ****** the rocker box. I had 3 shafts in my rocker box with loads of up and down play, so replaced it with the later rocker box with the pinned shafts.
The castings in your rocker box look really poor and maybe this is why some have worn badly. However as Bryanj has said if the bores are not oval and the shafts still fit well it’s ok.

[Seabeowner]

I think the pinned shafts were only introduced after about late 1975 or 1976. It seems that the problem only raised it's head after a long while. I have two rocker covers off K1s that came off engines that have over 50000 miles on them and both seem fine.
I have a later pinned set that shows wear on the shafts where the rockers rocks instead! No wear on the earlier non pinned shafts here.
Never seen anything like the pics above. Is it off a recent import bike?

[Bryanj]

Pinned shafts came in the K3 and maybe 76 F

[DomP]

Pinned shafts came in the K3 and maybe 76 F

My 76 F1 has pinned rocker shafts so that confirms that Bryan

[Kai.chris]

The cover does indeed have the pinned shafts.
Bike was originally an import from Italy over 25 years ago.
Good to hear I don’t need a new cover, bike has already broken the bank several times over. 

[Kai.chris]

Rev counter worm drive bore is also riddled with pin holes.
It must have been very poor to begin with. It’s not corrosion and can’t be wear in those locations as others have pointed out.
Possibly trapped air during casting, known as gas porosity.

[Kai.chris]

Not sure how to proceed now. Closer inspection of the cam, rockers and rocker pins shows worn pins where the rocker rocks as mentioned by Seabeowner.
The knock on effect looks like a ruined cam and rockers wearing on one side.
One cam lobe has a crack near the edge, it looks like the other side of same lobe had the same issue and somebody has taken a grinder to it. All lobes have uneven wear and pitting to some degree.
I was going to send the cam to Newman cams but without new pins(unavailable) and rockers (£22 a pop) there doesn't seem much point in re-profiling the cam anyway.
Where should I go from here? new head, cam and cover out of the question.

[Bryanj]

The small pitting is relatively common and wont hurt as the rocker runs on the middle, the rough edge howeverdoes look bad.

Now the head, cam and cover are the same on all 500 and 550 engines, i may have a spare cam and bare head but not a spare cover at the moment

[Kai.chris]

Thanks Bryan.
My cylinder head is currently with a local specialist having the valves cut in, won’t have started it yet.
Would it be unwise to say throw your spare cam on my cylinder head, or are
your cam and head matched? How much does it really matter for a bit of gentle back lane riding. 
I’ve managed to source 3 of the 4 rocker pins NOS but they won’t be cheap.
Am I overthinking it all, tempted just to knock that rough piece off the cam and throw it back together. £2k in parts and now this, the gift that just keeps on giving 

[Bryanj]

I can find you a cam, pm me and i will work out how much, head, cam and camcover are all made seperately so not necessary to keep together, secialy for a low mileage use gentle rider, full nutter racemobile different!

[Oddjob]

If you’ve found 3 of the 4 rocker shafts nos you’re doing extremely well. Are you sure they are the pinned type though? Honda did the longer rocker shafts on the late 500-4 but they weren’t pinned, just long shafts with no cutouts for the locking pin. Easier to find those, which is why I ask.

I was looking for pinned shafts a few years ago and whilst some sites said they had them in stock they didn’t when you ordered them.