W/NG - Smoke and tappets

Having recently retired around the time that the sun came out and the Coronavirus lockdown regulations were loosened here in the UK, the bikes have been seeing a bit of use. This week, I went out with my son on a ride around Coltishall, Norfolk:

That's his Interceptor, which is a fine machine with power low down, a nice seat height and good balance. We tootle around for a bit, testing out the W/NG's new baffles which seem to be cutting the noise down but also seem to have affected the idle - it now dies more readily than it used to.

However, I adjusted quite a lot of play out of the tappets before I left and that reduced the clatter quite a lot, and the bike seems to be going well. I had it up to 60 on the way home, though by the time I stopped there was smoke pouring off the cylinder head and there was quite a lot of oil about - disappointing, as I had resealed the rocker shaft unions which had been weeping for a while. I resealed them discarding the traditional fibre washers for soft aluminium washers, so we will see how that pans out.

So, back in the workshop the spanners are out to have another go at those unions. There's oil everywhere - under the tank, on the mudguard and down tube, all over the timing cover. It has never been this bad.

Then the penny drops - Numpty Spannerman has been at it again, taking stuff to bits and not putting it back correctly. The front rocker cap has gone.

I've often found that I've subconsciously registered some change in engine note or handling performance during a trip, only to realise the cause much later - the senses are very good at picking up small changes. This time, on the way down I had noticed a deepening of the engine note and on arrival there was more oil about in new locations - differently shaped dribbles even.

So that spelled the end for the old brass rocker caps, one lying in a gutter somewhere in Norfolk and the other consigned to the spares box, to be replaced by these fine reproduction examples from the AOMCC Singles Spares scheme. Also shown here are the clips that hold them in place - this is a W/NG only part, and provides some deterrent for the caps to loosen off completely.

Whilst I had the tank off, I took the opportunity to check the tappets again, look at the decompressor seals and check the timing. The tappets and timing were spot on but while I was removing the rocker box bolts to fit the new clips I returned the clutch cable to it's proper route - it's not supposed to go through the tank mount like this:

Here's the decompressor, removed and dismantled:

I've fitted a Dowty washer between the body and the rocker box to seal that joint. Third from the left is the rubber washer, which is rock hard - I fitted a small O ring behind this. O rings are not for use in dynamic sealing applications, but the decompressor rarely moves so I think it will be OK. I've had a quick look for an oil seal that will fit in here but that seal is maybe 2 mm thick - way too thin for an oil seal. Perhaps I will turn a simple carrier to fit a couple of O rings or change the decompressor body to allow an oil seal to fit.

I'd not noticed this weld repair before.

So that was a useful couple of hours work - I had a look at the clutch adjustment as well. These old bikes are so easy to work on.