Posted by John MC on 11/05/2019 08:18:24:
Posted by sparky mike on 10/05/2019 08:36:20:
The reamer will not produce a good enough finish and chance of getting it off square to the cylinder barrel.
Mike.
Totally agree. The small ends really need to be bored parallel to the big ends. While a good (sharp) reamer will produce a size/plus hole with good repeatability it may not be the right size for the pin or a good enough finish. My preferred method is to bore a small end bush to within a couple of thou and then on to the (Delapena) hone to finish.
Velocette made some of their small ends neither metric or imperial in diameter to discourage the use of a reamer to finish the bore of the bush. Problem was that it was easy enough to get a reamer ground to the size required……
I good attempt to encourage getting the job done properly.
John
Dunno about that. A lot of Harley small end bushes are an odd ID, something like .792". But the factory workshop manual specifies to use the factory service tool – a reamer, which was avialable only from them!
Then the factory manual recommends checking the wrist pin for square with the crankcase mouth and if it isnt, to use a big long lever special tool to BEND THE CON ROD
to bring the pin back to square.
Go figure.
I have never had to go the last step. With careful reaming of a bushing not too far undersize to start with they always seem to come out square when checked. Of course with engine disassembled it's best to do it in a drill press or mill to ensure squareness. Thing is, I found the drill press my old man used for rebuilding Harley rod sets for years had 20 thou droop on the table front to rear. Yet those rods and small end bushes worked just fine and are still running today. Must have by luck (or maybe he knew?) had the rods oriented the right way so the error was radial and not axial when reamed.