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tomshep

The engine rebuild...

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Long John Rotax wanted a fortune for the bits I wanted because one cylinder needed a rebore so I asked the Americans
If anybody had used non Rotax parts and lived to tell the tale. They told me it would be perfectly OK and I bought a pair of pistons, gudgeon pins and a full set of gaskets for 250. The main bearings are to be changed as a precautionary measure, the front one feeling less smooth than I would like. That meant pulling the old ones off. Nobody had a suitable puller but one of my colleagues had a stainless steel doughnut on his desk. 125 diameter, hole in the middle 65mm and 18mm thick. Better still, it was drilled to an M8 tapping size on a PCD of 82mm! He was glad to find a good home for it so I went down to the mech shop to see Martin. Martin, a skilled turner had just bought himself a lathe to put in his shed, so I gave him the job of turning the middle out to 72mm, leaving a nice chamfered lip at the bottom to carry the bearing.
He did that and I sawed the doughnut into two c shaped halves and tapped the existing holes. I ordered a piece of 8mm thick mild steel and bought some stainless studding. When the steel arrived, I drilled three holes in it to match those in the stainless parts. A very big hose clip to keep them from spreading and I had a bearing puller.
Two weeks it took to put it all together from the initial idea. Did it work?
Yes, for ten minutes. That was all it took to remove the three bearings! Next week, the company's test chambers will be set to +85C and -40C overnight and I'll be in early the following morning to fit the new bearings. The rebored cylinders will be back as well, I expect so next weekend will be spent putting it all back together.Click image for larger version. 

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