Put it all together yesterday. It started first pull and runs great.
Only problem was with the old engines I bought from the tip. After I cleaned the oil and dirt off the flywheels, I found all three had similar hairline cracks in them. In all cases it is a fine crack around one fin which goes down as far as the magnet. There are no signs of cracking on the inside of these flywheels. I decided to use the best one. After running the engine for about half an hour I pulled off the cowl and inspected the crack. It was still the same and had not grown any further or opened up at all. It is of course potentially dangerous. Considering this is essentially a display engine which will never be used for any heavy work, I think it will be okay for the time being. I will of course replace it if I can get hold of a good flywheel. Generally cracks are only really bad if they extend through the centre of the flywheel, close to or across the shaft. This one is confined to a fin on the very outer edge and only on one side. It could survive for decades in this condition - it may have even been there from day one - but it could of course fail at any time. Considering I bought three old Rovers from the tip and all of them had hairline cracks concealed under half an inch of grime, I wonder how many people out there are mowing their lawns daily with similar cracks in the flywheels? Most people never inspect them and would be blissfully unaware. If I had not thoroughly cleaned down these flywheels I would have been completely unaware of any problem.
Those with poor eyesight may also be at a disadvantage. I recall an elderly relative was fixing his mower one time. I picked up the flywheel and said "Looks like you've got a cracked flywheel?" It was news to him. It had a hairline crack running right across the middle!
