Hitchcocks Forum

In the used section on this site there are two 500 heads Item USED 2034 & item USED 2030 they are listed as having different size oil ways, the head from an ES has small oil ways , and the head from a KS has large oil ways, question is why would this be ? both 500s why would they be different?

I think this is probably referring to the size of the threads cut for the rocker feed banjos. There are two sizes. If you had the wrong size, your banjo bolts, sealing washers and oil feed pipes wouldn't fit. You'd need to replace these if you were fitting a head with "small" holes to a bike with "large" pipes. If you were fitting a had with "large" holes to a bike with "small" pipes, you can fit a couple of adapters. Our hosts make them but don't advertise them separately, I'm sure they'd sell you a couple to go with the head though if that's likely to be an issue.

As to the initial question of "Why?", not sure. Possibly the family in charge of the cottage industry of tapping cylinder head banjo feed holes broke their hereditary tap and had to buy a new one. Or it is easier to get metric banjo bolts? I don't think it makes any difference mechanically so there is probably a more mundane reason like cost or availability.

Thanks for your reply StinkWheel, I was just curious as to why there would be two sizes especially as H states ES and KS, your answer is logical though, perhaps a change in manufacturing or even a different plant one for the ES and one for the KS , because it shouldn't matter either way ES or KS if its the same model type.