Project Morini
The chap from Hamlins Engineering said: “I've got some good news and some bad news.” The good news from the engineering shop really was good – for my pocket, at least. I'd presented Hamlins with a mushroom crate containing four barrels for the
Morini. Two were the originals and two from my parts engine. I also had two standard bore pistons. I took the barrels to Hamlins for checking, as parts supply was going to be an issue. Oversized pistons up to 63mm are unobtainable, but I could get new standard bore pistons or I could get the barrels rebored out to 64mm, increasing the capacity by 25cc. Pistons for this, known as the 375 conversion, are also available, but it does make the liner very thin at the bottom. The cost of parts alone was going to be well over £250, plus the price of a a rebore.
I asked Hamlins to check all the bores and the pistons to see which was likely to be the best option. The two original barrels had a fine dust of corrosion, while those on the parts engine had been protected by it not being dismantled.
As it turned out, Hamlins found that despite the bike covering 38,000 miles, the bores had only got wear of 0.3mm over standard. All I needed was for the barrels to be de-glazed and some new rings fitted to the old pistons.
Rings were acquired from Cox and Turner, engineers in Tintinhull, near Yeovil, at £12 each. Cox and Turner has a huge stock of piston rings stock rings from around 1in diameter to approximately
9in diameter. Oh, and it makes rings too – up to 36in, and can match a ring from a broken example, so is worth checking out if you need something obscure. This, then, was excellent news.
Less enervating was the news that my swingarm was bent.
I discovered this after I was contacted by CBG reader Andy, who said he had a few spares he might be able to help me out with. These included a replacement for my missing clutch cover, a single clutch spring nut, and, importantly, a swingarm spindle with new bushes. My old one had a lunched thread at one end and had suffered considerable wear, so this was especially useful. I popped the new bushes in the pivot, slid the shaft in, and it didn't fit. Initially I thought this might be down to inaccurate machining of the bushes, so I took it to Hamlins to see if they needed reaming. Unfortunately, it appeared that the pivot points were bent out of line.
I think that this may have happened decades ago when I farmed out the fitting of a set of bushes, or possibly it got dropped from a height at some point in the years of storage. Fortunately, the bend was only a few millimetres out of line and straightening the swingarm was possible, I was informed, but sadly the process would damage the shiny new powder coating – and there was no way around it.
While waiting for the work on the swingarm and the barrels to be done, I got the bottom end on the bench for inspection and cleaning.
The lack of wear on the barrels introduced a conundrum. I'd never had an issue with the Morini's bottom end, and external inspection indicated there was little or no wear, apart from the small end bushes. The original gudgeon pins were now lost and I recalled they had suffered some wear, but the ones salvaged from the parts engine are good and can be used again. The oil seals, having been left for 25 years, are likely to be dried out. Given that seals are not expensive, it seems sensible to change them. I would also like to get the crankcases vapour blasted, but that will mean a complete strip of what I am sure is perfectly serviceable bottom end.
I knew the camshaft drive belt was going to need replacing, which requires the removal of the alternator. The thing to do, I decided, was to pull the rotor to see if the oil seals beneath can be changed without pulling the casing apart. This will require the use of a flywheel puller. I have a flywheel puller that was made by turning a fresh thread onto a Lambretta puller back in the 1980s, when such items were harder to find. I found it again in one of the boxes when I pulled all the bits out of the garage, and I cleaned it up and put it “somewhere safe”... and now I cannot find that “somewhere safe”. Despite tearing the garage apart, it had vanished into thin air.
I decided to bite the bullet and buy another. With a stroke of luck, an eBay search found a chap selling not only a puller, but also a new old stock cam belt. The cam belt causes much discussion in
Morini circles. Officially there are three potential cam belts that need regularly replacing, and these come as A, B or C belts. The type of belt you need is stamped on the cam belt pulley, and mine needs a C, while my parts engine has a B-type pulley. Morinisti often debate whether to use the official belts, which have been checked on a jig and cost £35, or generic copies from Continental that are not graded but cost just over a fiver, as they should be replaced every couple of years anyway. The new belt is a B type, so I'll need to swap the pulleys round when I've worked out how to pull them off.
When the engine was removed all those years ago, I didn't do any major work to clean off the oil grease and road dirt at the time. This turns out to have been a good decision. The muck had protected the casings from corrosion and getting it off may simply require many hours of work with gunk and paraffin, a brush and wooden scrapers.
The rotor and the alternator windings are now removed and remain in good condition, and the old cam belt was torn in two removing it, so yes, they do deteriorate.
After inspection it looks like pulling the crankcases apart is the sensible thing to do. Removing the rotor revealed a couple of washers that had fallen into the mechanism while in storage, and there was certain amount of dog hair. As with all restorations, this is one of those one-step-forward-twosteps-back jobs. If washers and dog hair can get inside the alternator, who knows what lurks inside the crankcases?