Well… after a long search (which I’ll attempt to summarise below) and a fair amount of effort, the Matchless is up and running again! It does need to be run in, however, which is going to involve riding 500 miles at 30-35mph! This, of course,  is far from ideal, but it must be done to ensure long life of the new piston rings, and no engine seizing! Anyway… onto the story since the last post.

The piston I picked up from AMC Classic Spares, although the correct diameter, was definitely the wrong one (this was not their fault, I might add) and although it could potentially be milled out, I decided to wait and see if a proper, original, BHB piston was ever going to turn up. This piston is therefore sitting on my shelf right now, waiting for me to sell it back to AMC Classic Spares if they’ll take it!

The main problem was that even if it could be milled, the metal underneath the milled area would have been very thin, and the reinforcement ridges built into the casting of my original piston don’t exist on this new one, so it would be far from ideal in this situation.

Having almost given up on the new piston, I started to phone the rest of the places on my list, in the UK and abroad! I even, accidentally, woke up someone at home in Australia at 4am, having got the timezones 4 or 5 hours out compared with the UK! I knew it was morning over there, given that it was evening over here, but I wasn’t sure how early in the morning it was. I figured that given this was a business, if the business was closed I could leave a message, but it was actually a house phone, so there it was – the call at 4am!

After phoning all of the places on my list though, I gave up hope of finding one via the web or over the phone and started hoping the adverts placed in the various magazines might throw something up.

Before these were even published though, I received a response on the club web site from a club member in Canada who had an original BHB piston, part number 030148, which had been sitting on his shelf since 1977, which I was welcome to have if I wanted!

So, this piston was posted to the UK, and 12 days later it arrived. Once cleaned up a bit, I revealed the same part number as my cracked piston!

Excellent!

So… into the bike it went, and after 2 hours in the garage, on the 5th kick, the bike started!

The next day I set off around town for a couple of miles to see how the bike ran, and to begin the run-in process, but once the bike warmed up, there was a distinct rattle from somewhere in the engine.

I adjusted the tappets, the day after, and went out again to find that the rattle was still there. When I got home, I adjusted the tappets again (while the bike was still warm this time!) and since then, I think the rattle has gone away.

I’m 35 miles into the run-in period now, and I still can’t hear the rattle, so I guess it really has gone!

The trouble is… I’m now questioning both my memory of the rattle, and my audio observation skills. Perhaps the rattle is still there, and I just can’t hear it for some reason… perhaps the rattle really has gone… perhaps I’m over-analysing things again!

I guess I’ll know for certain when I have a second opinion from someone who actually knows about these things!

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