johnm said:
Les Emery. Tech talk. D rods be gone.John
I scrapped out 3 850 engines and still have the rods out of them here, all three engines used rods with different stampings side to side. The E-start had a D rod in it. Les Emery has a slimy enough reputation that I would not listen to anything he said, and would not be surprised if he bad-mouthed stock parts just so he could sell some new ones to put extra dollars in his pocket, that is what he is all about.
Expanding on what Hobot said about the Hogslayer, the man who built it John Gregory told me that in the early 60s they ran nitro burning bikes with the early 650/Atlas rods that had less meat around the base, the Bracebridge Street jobs, and he never had one of those break either, he said it was just important to have them torqued up to spec. He suspected that some of the early 650/750 engines got their rods torqued to the lesser 500/600cc value and that may have caused problems and a reputation.
I am sure that lots of 89mm stroke Nortons have lost con-rods, but there are so many factors that could trigger that event that it would take some real research to get the facts, and I don't know of any that has been done, and at this late date all that is left to test is old used rods anyway. Oil pressure can be marginal, there is the known aluminum-chip under the rod-bolt head trick etc.. The early 650/750 rods were installed with un-polished beams with a very rough ground parting line, and there are some of those still running around, I ran a 650 with those rods down a drag strip more than once with no problem.
If the rods are for a street bike, assembled by a good mechanic and ridden by a sane man history shows they should work well no matter if they are from a 1961 650 or a 1975 850.
