I've taken the opportunity to remove the petrol tank because it's time I did the valve clearances and had a look at a persistent oil leak that has been going on for years. I thought it was fixed; I changed my mind and decided it was a head gasket problem - but then careful observation of the rocker box oil line revealed some seepage. It's obviously been quite bad in the past at some point, before I fixed it last time, because there's oil on the steering damper plates under the steering head. There must have been quite a jet to get it out there.
Some years ago I did repair a leak here but it appears I didn't do it very well:
When I took this apart it was clear that they was some oxidization within the joint which had prevented the solder wicking down inside the fitting. I cleaned that up with wet and dry and tinned the pipe with some solder, using plenty of flux to sweat the joint into place. It resists that twisting now.
The next job is to do the tappets and pulling off the rocker covers reveals some lovely clean valve gear.
These are all supposed to be set to 0.001" with the engine cold. I used the famous 'Rule of Nine' to set them up.
Valve clearances all proved to be very close to where they should be - I adjusted a couple of them but most of them were ok. I moved on to the spark plugs - cleaning them, checking their gaps but again they were all ok. I took the opportunity to change the thumb nuts holding the HT cables to the plugs for some larger ones that I made some years ago.
With the rocker cover off I took the opportunity to snug down the head bolts and nuts. This is quite straightforward except for the pair that are buried in the fins - these two at the back are particularly difficult and you have to take the carburettor off to get at them. The one on the timing side of the bike is almost impossible because the casting has not been cleaned up sufficiently for you to be able to get at the nut.
Next time that I take the head off, there will have to be some grinding in there.
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