it’s in bits n pieces

and everything looks good; very good.

The beauty of such a small engine, is it’s so easy to work on but care needs to be taken as everything is smaller and more easily damaged.

The clutch housing is removed and everything looks good.

Even better, the disc valve is in really good condition. The steel disc (RH photo) is usually badly corroded on engines that have stood like this one, as they don’t run with much oil in the crankcase. So I’m now certain the engine has been re-build then never used. The disc valve was a very advanced design in the 50’s and is crucial to the (relative) excellent performance this engine. It was renown for excellent torque compared to larger capacity engines and out performed many 50cc engines.

The crankshaft is beautifully made and you can see the piston is in very good condition. It’s not unused as there is a little bit of scuffing on the piston skirt, from the barrel exhaust port, so I’ve gently smoothed it with 1200 grit paper. I’ll also add a very small radius to the top and bottom of the exhaust port with a needle file.

I’ve sanded the bore with 1200 wet and dry paper to help the rings bed in. The slightly rougher surface holds a little oil which reduces the risk of seizure whilst the rings bed in. The RH photo shows the piston support I made to hold the piston for the barrel to be fitted.

The cylinder head and barrel are so well made, that a gasket isn’t needed, just a smear of gasket cement to ensure a gas tight seal. Before fitting the cylinder, head I took the opportunity to mark TDC (top dead centre) on the flywheel (RH photo) and 7/8″ BTC (before top dead centre) which is the position where the points should just be opening, so setting the ignition timing should be easy and accurate.

Back together and read to go.

However, I can’t start it until it’s fitted to the wheel and I can’t do that as, a) the sellers weren’t able to find the missing eccentric (but they did find the drive chain) and b) when I checked the wheel hub bearings an inner cone was badly worn, so it’s still in pieces – see cone below.


The gouged groove in the centre shouldn’t be there. These parts are often just case hardened which means just the surface is hard and on this cone the hard surface has worn through, so I need a replacement. However, I’m told these parts are like the proverbial “hens teeth”, so that’s my next challenge, find a hen with teeth…


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