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Velocette TT winners
Top End Timing Chest Crank Cases Flywheels
Rockerbox Other Stuff Gearbox Summary

It was obvious as soon as I pulled the barrel off that the bigend had bundles of excess play and the flywheel had a lot of end float, the flywheels also had vertical shake. The little end was also pretty worn. The crank was very loose in the timing side bearing, I was expecting a snug fit on the tapered timing pinion. The ends of the crank had the hammered look, not that it mattered as the timing pinion needed replacing.


Figure 1. The timing side pinion, can't imagine why anyone needed to batter hell out of this. Unless it had sommething to do with hammering a bearing on the wrong way?
Figure 1. The timing side pinion, looking good?

The Timing side ball race didn't look at all bad, I couldn't spot any pitting or shake. But the bearing had been put on the shaft the wrong way at some time, well thats what it looks like, the pinion has what looks like a radial shear line and the bearing goes on either way;-) The bearing had signs of wear on the inside of the race and when a replacement pinion was found the bearing was a very loose fit on it and went on that either way! I didn't actually entertain the idea of running the old bearing just checked the fit. The surprising thing is the route some of the the metal from the cam took to get to the bottom of the motor would have been thru the bearing, which doesn't look to bad? The drive side ball race has a lot of pitting and needs replacing.


Figure 2. Timing side flywheel crank pin oil way, it's the thing in the centre full full of hard crud.

When I pulled the crankpin out you could see the oil way was blocked, it had a plug of solid dry crud that was firmly blocking the oil way, the crud had to be drilled out. So it hadn't had any oil feed to the big end, I suppose wet sumping has some benefits;-) The engine breathes through the drive pinion, from inside the motor is an axial hole down the drive pinion, which is intercepted by a radial hole from under the sprocket. There was a bit of aluminium hammered into the hole under the sprocket, to block it? So the motor breathing was thru the drive side main bearing and everywhere oil poured out of the motor!


Figure 3. Well what can I say, one cracked con rod race. While the cracks are un-missable on the sides they are barely visible in the bore of the race. I almost missed them, OK I am telling porkies you need to go to specsavers if you missed them.

The big end is excessively worn and the entire assembly needed replacing. I bought a nice fresh Alpha bigend. I was going to replace the timing pinion in the flywheel, but it would have cost as much as a secondhand flywheel assembly; there was also the vague chance the bigend in the secondhand flywheels would be usable, I would have been able to could send the Alpha BE back and recoupe 200 smakeroonies; but no the bigend in the replacment wheels was pretty bad. So I stripped the replacement flywheel assembly and replaced the bigend. What do you know the 'new' flywheel assy had a timing pinion that had seen a hammer as well! I was using a box to true the wheels but felt I should clean the center anyway, well the oil feed quill goes in it so nice and tru is best. The quill from the original flwheels was nearly worn thru and I guess that's when they break.


Figure 4. Checking the flywheel axial runout, prior to removing the pinion run out.