harleyKmodel

So where are yall getting the K pistons from these days?

I see that Truett & Osborn sells pistons that are made by another (unnamed) party. I have never done business with T&O, but they seem to have a good reputation. I do not imagine they would sell a bad piston.

I have a set of T&O stroker flywheels and the pistons, but the pistons, with short skirts and wrist pin location changed for the stroke increase, are still the same as stock pistons, as far as relationship of the top of the piston to head gasket surface, I understand the K pistons have a large positive deck and the stock 45 pistons have a large negative deck.

Eastern motorcycle parts sells them. They are wholesale only, so you'll need to go through a retailer. Most of the large parts dealers (J&P, Dennis Kirk, etc.) are eastern retailers.

Download their catalog! They have some items, like K/KH sprocket and pinions shafts, that don't seem to be available elsewhere.

I'm an Eastern dealer and keep some pistons/rings in stock. PM me if you need help ordering.

Thanks Max. Will do

Coolbreeze wrote:I see that Truett & Osborn sells pistons that are made by another (unnamed) party. I have never done business with T&O, but they seem to have a good reputation. I do not imagine they would sell a bad piston.

I've done business with T&O. Actually got them to rebuild and modify a complete engine for me. That engine just ran 3rd in the Victorian Titles a few weeks ago. These guys have a LOT of experience. Visit the shop if you ever get a chance. It's a time warp.

After reading this thread it reminded me of a time years ago when we were at Wauseon and a fellow had a nicely restored '52K. We watched him run around the meet and saw him start it a few times. The motor sounded flat, really flat. When he would start it you could tell there was little compression. It almost looked like you could have turned it over by hand. A buddy of ours says, I bet he used 45 pistons. I imagine that was done by more then a few people back in the day. Maybe some still do. I was curious to see what the difference is between the two pistons so I picked up a used 45 piston to compare with a K. The 45 piston is .095" shorter in height in relation the the piston pin or a hair over 3/32". I can see now why you would have very low compression. I am assuming it would be the opposite using a K piston in a 45 motor and am curious as to why you might want to do it. I am no motor head but always curious and usually explanations are required for this feeble brain to understand.

to raise the compression

I am assuming it would be the opposite using a K piston in a 45 motor and am curious as to why you might want to do it.

K type pistons were firstused in later WRs, not to raise the compression, but to increase the squish. They are used in conjunction with heads that have a milled relief in them to allow the piston to "pop up" into the head and create a greater squish of the mixture than just raising the compression can do. It forces the mixture across the the valve area where the combustion is taking place. When H-D designed the K they used a lot of WR ideas in it for increased performance over the old WL.