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Cushman Scooter Engine Rebuild

dkirk

Registered
Oil pump is fitted to block and retaining screw/clamp tightened. Crankshaft and camshaft can now be fitted and timed. Takes a little practice to get the oil pump pushrod pressed down against the pump spring to get the camshaft inserted as the pushrod must ride on the oil pump cam.

Once these parts were installed, the side cover was ready to be fitted. I coat all gasket and shim surfaces with Silicone grease - this allows easy removal should it be necessary in the future. Gaskets don't stick to surfaces thus no scraping is necessary. Also seems to prevent oil leaks. The side cover then can be fitted and torqued down, and crank and cam end clearances checked. I measured the shim stack-up on disassembly and refitted the same thicknesses on reassembly so all clearances are to the manual specifications.
 

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dkirk

Registered
Next, piston and rod were installed in the block after checking that rotating assembly turns freely. Bore, piston and rings were lubricated with engine oil and ring gaps staggered. Piston was then inserted using a ring compressor and rod cap was fitted after oil was applied to crankpin. All new high-temp lock nuts were used and torqued to proper spec (12 ft-lbf). Rotation was then checked and engine turns freely. White lithium grease is applied to both intake, exhaust and oil pump cams for good lubrication on the first start.
 

Attachments

dkirk

Registered
The sump plate cork gasket gets the Silicone grease treatment, both sides. As the sump plate retaining screw bosses are through-drilled in the block, oil can weep around the screws causing the notorious oil leaks that many of these engines have. I applied a small amount of Silicone RTV to the threads to prevent this. I only torqued these screws to 20 in-lbf as it's easy to get carried away here and distort the sump plate.
 

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