Off with his head, part 3 – 29 Jan 2017.

As I said yesterday, I’ve decided to repeat the work on the left hand cylinder, mainly for the sake of thoroughness. It’s also a chance to examine the condition of the cylinder bore and rocker gear.

Oh what fun I had! This time the exhaust header nut was very tight. Not only that, the notches for the c-spanner were a mess. I had to start by knocking the ring nut back and forward a tiny amount and dosing it with WD40 just to get it started. It was clear it had been hit with a punch or possibly a chisel before. It took me about an hour and a half to get it undone. When it did turn, it would still bind at the same point in every rotation. Once off I could see it was clearly distorted. It wasn’t me, honest! However, it was me who let the c-spanner slip and chip the paint on the fuel tank. It was clear that a “Gun Gum” type sealant had been used and was the main reason the thing had been stuck. Happily the exhaust port threads on this side were undamaged.

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The cylinder head nuts were tighter on this time but, when I lifted the rocker bracket, there were no O-rings where they should be. It turned out that they were fitted to the four long studs under the head gasket! Don’t do it like this.

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Again the rocker gear is in very good condition. It looks nearly new. It’s strange that this (expensive) work appears to have been undertaken but basic mistakes made.

Once again the cylinder barrel is the chrome plated type and in very good condition. The two bottom O-rings were where I would expect to find them.

Putting everything back together was easy enough but I discovered this chip out of the rocker bracket.

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It’s where the shaft-locking screw goes on the exhaust side. When reassembling the gear I was careful not to let the end of the lock-washer catch in the hole. I don’t feel able to weld the chip as the bracket is a casting. I think, at some point, I’ll run the engine with the rocker cover off to see if oil is pumped out of here instead of lubricating the rocker and shaft. Hopefully it will seal. If not, I might look for some sort of “plastic metal” to repair it but an oil-soaked casting might prevent it “taking”.

Again I have put the rocker cover back on without adjusting the valve clearances. This is while I turn my attention to the mullered exhaust head nut.

Replacements are quite pricey and the original type don’t seem to be available any more. Instead the better type with a lock-ring (as I have fitted to the V7Sport) can be had for about £50 a pair. Here’s what I mean on Rhino.

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I do have a couple of exhaust nuts which have been sawn lengthwise. I did it over 30 years ago to allow the rings to spread a bit to get around the sharper turns on a 850T3 shaped exhaust header. Once past the obstruction they would go back to their original size and screw down on the exhaust and still compress the gasket. The trouble was they would (unsurprisingly) come loose if not wired to a drilled cylinder head fin. At the time this was OK as they’d always had to be lock-wired anyway.

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In an effort to save money I decided to try and braze the gap. It wasn’t entirely successful because I couldn’t get enough heat into the job with my little oxy-propane set-up.

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I haven’t fitted it to the bike other than to check that it threads into the head easily. The repair seems robust enough. However, I think I’ll be making another order on the Stein-Dinse website. I’ll be hit with the minimum shipping cost again but, what can you do?

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