Early Model 25 engine?

Another Norton that used to belong to Ko Konijn, and much more interesting than you may think at first glance.

Simon: "The crankcase is almost certainly Model 25 or Model 21 though there is a very slim chance it could be one of the earliest ES2s (before they were called ES2s) which had a two piece timing cover like the M25s. The timing cover now on the engine is actually Model 18/16H or whatever - you can see it does not meet the lower cover over the drysump oil pump housing. The Best and Lloyd pump is feeding the inlet union of the dry sump pump - but perhaps there was no actual pump in there and it was internally set up so that it fed the big end etc via the usual dry sump quill...Who knows!!"

Markus's projects

Markus sent a few pics of the timing chests of his engines, showing the differences between the Model 18 engine (top) and the Model 21 engine (below). Note the "IT" racing exhaust cam in the M21 engine; the exhaust cam of his M18 engine is marked "K" and I would not know the significance of that stamping.

Markus: "In 2005 I had a bad experience with the Model 21 engine; I was overtaking a scooter at about 100 km/h when the engine suddenly lost power! You can imagine how embarassing that was...So I stopped at the side of the road and found all compression was gone. I pushed the Norton home for 3 kilometers at 30°C, opened the engine, and found a huge hole in the piston...I could see directly into the crankcase! Perhaps the combination of an old (non-Norton) piston and wrong ignition timing was the reason for this failure. I've now fitted specially prepared drop-forget Mahle pistons in both engines and haven't experienced problems since."

Jeff's 1929 Model 21 Norton

Sent by Reece, this is Jeff's 1929 Model 21. This motorcycle has a 490cc engine and 3-speed gearbox like the Model 18 but with a dry-sump lubrication. The reciprocating plunger oil pump was designed by Walter Moore and first used on Norton motorcycles in 1925. The external control on the lower timing case controls the pick-up level of the scavenge pump; set in the 'high' position the oil level in the crankcase rises and the engine becomes a semi-wet-sump.