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Messing around with a very worn RD17S. (Even the crankshaft is bad as the internal splines for the driveshaft are worn out). I got compression readings of 94 (top) 89 (bottom). Anyway on opening the crankcase there is definite looseness between the bushings in the rod small ends and the piston pins. The top is loosest but can feel/see play between the bushings and piston pins both top and bottom.
Would a fix be to replace the bushings? Has anyone ever tried that? Or would there be wear in say the piston that would preclude that? I looked in the parts list and there is no individual number for the bushings?
Thank you.The next year they replaced the bronze bushings with needle bearings – and replaced 5,000 powerheads under warrantee when the first bearings used failed. In testing they ran 1000 hours at wide open throttle. It turned out that at an idle the needles rocking back and fourth would ware through the retaining edge of the shell and drop out into the crankcase after around 200 hours.That of course totally destroyed the powerhead. Replacement bearings were a much better quality. Powerhead were sent to the dealers to replace all first production motors. Ralph said that’s what Ole would do. Some owners missed being contacted. Some were pleasantly surprised when the bearing failed five years later and got a brand new powerhead under there one year warrantee.
If you do remove the wrist pins, be sure the piston is well supported and push on the loose end. (Yes, the pistons are marked “loose” on one side, it’s a tapered bore.) If you push on the tight side, the piston will go out of round,
The bushings were cast in, but can be drilled out and reemed to fit the ’56 needle bearings. I was sure I had a service bulletin on replacing those needle bearings, but have not been able to locate it. (next year I have GOT to get organized) The needle bearing part number was 377260 –
Outboards 00001, 2 and 3 were run to death and torn down for analyses. Outboards 00004 through 05000 had the power heads replaced under warrantee. The suppliers specifications changed and the new bearings had the same part number abut were better quality. The only ’56 early serial number Big Twins that you would find with bad wrist pins today would be in an old dealers back room still in the sealed factory box. Any one who didn’t read there mail and ordered the bearings to fix a damaged motor under warrantee was sent a new powerhead.
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