need some help
Thanks,
Steven
Thanks,
Steven
The KR was a similar engine being 45 cubic inches but the difference of a KR compared to a K Model is the KR has a lot of roller bearings and needle bearings where the K Model has bushings.
The KR was the racing engine used on the dirt tracks and road races back in the day. First made in 1953.
So it sounds like some has taken a KR and put a Sportster top end on it having overhead valves.
This has been done before by others but is a hybrid for sure.
Some of the questions I have are as follows:
Since the KR is 45 inches (750cc) and the Sportster is 55 cu inches (900cc)......
What connecting rods were used?
What pistons were used?
What was used for push rods?
What was used for pushrod tubes?
I am thinking it must be Sportster rods, pushrods and cams, with a KR lower end and cases?
But I am not sure.
You basically are going to be using parts for a K Model for the bottom and parts for a Sportster for the top end.
The middle parts are going to be what ever it takes to connect the two areas together. So you are kinda on your own here.
Post a pic of the bike if you can.
Videos do not interest me like a photo would.
Here is a pic of my old 1955 KR dirt tracker. Your bike once looked just like this if it is a KR and was a dirt track machine.
If it was a TT or a road race machine, then it would have a swing arm frame, not the rigid frame of a dirt tracker......

pg
If possible, show a shot of.............
The pushrod covers and lifter bases.
The cast part numbers of the cylinders ( on the cyl bases on left side)
The right and left side view of the engine
The engine serial number on the left side of the cases just below the cylinder bases.
pg
If so, then the cylinders are 1959 Sportster, or later and are 900cc in size. That will mean the the connecting rod assembly is also Sportster.
I could not see what your pushrod covers and lifter bases look like but I have to assume they are the chromed tubes for a Sportster also.
So, you have a K Model lower end matched to a Sportster upper end. Nice combination.
pg
Trending Topics
http://books.google.ca/books?id=7KfX...%20KRM&f=false
Parts are available online ebay, J&P Cycle and others...google will help with that or search build threads and read what others have done. Buy quality name brand parts not cheapest available. Many parts are made in Asia. They are cheap, generally poor quality and are even sold in HD dealerships. Look for names like Kibblewhite Precision, S&S, colony...to name a few that are made in North America....you get what you pay for.
A quick glance through the J&P cat. turned up parts listed for the K models. Your bike has been modified, though, so it is anyones guess what else has been changed besides the obvious....won't know until you start looking. The big difference between the K and early 900s is the top end and yours has been changed. (Don't start thinking the bottoms are the same, though...as you may find out if it starts dropping out of gear. Sometime in the mid 50's a trap door was added for ease of access....but 53 sounds a bit early for that)
I'll be following this build. post lots of pics as you go. love the old stuff. nice find
Last edited by scottfisher; Jan 3, 2012 at 11:45 PM. Reason: spelling like a second grader
The Best of Harley-Davidson for Lifelong Riders
The lower end is 53kr m1572
http://www.flickr.com/photos/73465501@N07/6638705551/
http://www.flickr.com/photos/73465501@N07/6638706881/
Thanks for all the help so far,
Steven



