The rockers are notoriously close to the internal camshaft tunnel. Is it possible to remove the side cover to occasionally inspect, without taking the entire top end off? Mine has a perfectly satisfactory steel tube ( repaired, as is apparently very common) many years ago. I suspect the holding down bolts might all need to be released, and the two on the left removed? It might be awkward to get the cover back over the roller bearing?
Why the curiosity ?
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Thanks Jon. I've been in…
Thanks Jon. I've been in there several times in largely vain attempts to reduce oil leaks. It was a bit scary the first time, but I'm confident I can get it back together. Pads and cams are good (or were last time). I never seem to have enough pictures. The exhaust rocker is very close to the tunnel, but not touching it. I doubt if clearance is much more than 20thou. I didn't measure it. I'm just conscious of the risk and I know it doesn't have to wear much to strike the tunnel. George Cohen describes his cambox repair, and mine seems to have a steel tunnel in the magnesium box. I suspect that the steel isn't likely to snap if it should ever come into contact.
My adjuster is extended more than I like. That's what's worrying me.
Endoscope sounds a good idea! Drilling holes is a bit brutal. Perhaps I could extract the pad next time, and add a washer behind it. I've obviously no idea what the original dimensions were and if mine are correct. The extreme solution is to replace with roller followers.
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George Cohen
Repaired my CS1 cam tunnel in about two hours. He had pre slotted tube with a countersunk hole to screw and glue to the casting. Machining out the destroyed tunnel (lost the exhaust rocker spindle) was the biggest job. Sounds like you are already suffering with tapped pad wear. Should you touch the steel repair you should not get into too much trouble, it’s only valve spring pressure. Get to the end of the riding season then sort the issue. Jon
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Thanks for the comments…
Thanks for the comments Jonathan. That makes sense. I don't think the rocker will damage the tube unless it's a lot worse. I'm off to Brooklands motorcycle day tomorrow..about 30 miles each way. I'll keep the speed down on the A3!
I might take the cam box off again next week to check it again. But first I'll check if valve clearance grows tomorrow.
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Do you have cause for concern David? The cam tunnel is normally aluminium as part of the cam box casting. A steel insert repair ? interesting solution depending on method of fixation.
The clearance between the standard tunnel and rocker arms is generous unless you have excessive wear in the "Tappet pad" or a collapsed needle bearing in the rocker.
If your adjuster is not excessively extended to close the tappet gap I would leave as is.
The cam bearing is in the cover and the rocker shafts bolt through it. This means removal of adjusters to take pressure off the shafts; to remove the shafts the nuts and split pins need releasing, then cam alignment to get everything together in the vertical plane, then the flimsy gasket to reseal all seems excessive to inspect something you cannot adjust.
On your next teardown maybe an inspection bolt strategically sizedand mounted in the cam box to insert an endoscope?
I am sleeping dogs kind... Cambox building is a bit of an art, doing it successfully in situ is a big ask.
Cheers
Jon