Board index Flathead Power-Technical Questions, Answers, and Suggestions K-Models Building a KR engine for racing

Building a KR engine for racing

Moderators: Curt!, Pa

Post Fri Oct 29, 2010 10:21 am
panic

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Last edited by panic on Sun Nov 28, 2010 12:10 pm, edited 1 time in total.

Post Fri Oct 29, 2010 10:49 am

Posts: 587
Location: Crewe, Great Britain

Hi panic,

Don't know!!!

I was talking about the Jerry Branch short rod KR, photo and titbits of info on page 116 in American Racer 2...

Waffle Iron XR had std KR/XLR rods in 70, so were just short stroke. The factory Iron XR got to prototype the shorter rod from the alloy XR in 71 so they were both short stroke and short rod. OB has stated that they got about 80BHP out of these later Iron XRs with the reworked twin carb heads while the proto alloy XR was worth about 70BHP in 71, But he obviously knew development would soon cancel the difference!!!

panic: the existing race cams are all too hot


Yes, but in the case of the XLR/Iron XR, it's all about getting a big overlap to compensate for the high dome that masks most of the overlap period by sticking so high... Same for std Sportsters actually...

panic: meaning the heads need a major re-design with smaller ports and valves


See previous photo, these are Iron XR heads, fitted with smaller cores before pouring. You can see the outline of the std core as well!!!

Patrick

Post Fri Oct 29, 2010 7:45 pm

Posts: 51
Location: felton,Ca.USA
Girdler tells us Len Andres built one as well, but never seen any evidence of that KR, it could not have been for Brad and what I see of Lasher or Rayborn rides in the mid 60s looks like std KRs...

Patrick
I have an Sifton/Andres motor sitting on the floor here at my shop stamped 52KR with the case numbers that Joe Leonard's bike had when he won the Springfield mile. I see Joe every week and he told me after that win Sifton sold the motor to Andres. It is a short rod but the front mag was still used. Bottom of cyl. exhaust spigot is ground down and the case is notched for pipe clearance. It is set up for dual carbs with fabricated tubular manifolds brazed into the cylinders. But Joe did not remember it having dual carbs when he raced it. Leonard A. probably did the modification.
Chris And I recently bought all the parts that our late friend and forum member Jim C., (XLR) had in his garage. Years ago Andres HD in San Diego sold all of thier old bikes and parts to Custom Chrome in Morgan Hill. Jim worked for them at that time so he had first shot at all of the race pieces which included this motor. We also got all of the KR cylinders and in those are two sets shortened to different lengths, 3/8" and 7/8" shorter than stock. Two set are NOS shortened by cutting just above the flange and brazing them back together. Another ser has screw on tubular manifold for dual carbs and a pair of mirror image Linkerts with the cast iron throttle bodies brazed together with a common throttle shaft.
As to how they shortened them as some one stated they were cut on the diagonal welded back together. I will try to get a picture of one of the rods but I do not see any sign of the welding which if the filler rod was the same as the rods it may not show.
Cool stuff. I will take some pictures and post them soon.
Mike

Post Sat Oct 30, 2010 2:26 am

Posts: 587
Location: Crewe, Great Britain

Hi Mike,

Thanks for the info, waiting for the photos impatiently!!!

One thing still puzzles me, if the rods are shortened and them being tapered, they should show a step along their lenght after the welding?

Or, more likely, did they also cut a triangular slot in the web of the bottom part to bring the front and rear faces in line with the top unaltered bit?

Yes, Jim/XLR was quite knowledeable and selflessly willing to share his experiences...

Patrick

Post Sat Oct 30, 2010 7:16 am
panic

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Last edited by panic on Sun Nov 28, 2010 12:10 pm, edited 1 time in total.

Post Sat Oct 30, 2010 7:23 am
panic

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Last edited by panic on Sun Nov 28, 2010 12:10 pm, edited 1 time in total.

Post Sat Oct 30, 2010 3:04 pm

Posts: 587
Location: Crewe, Great Britain

Hi all, 1st, a very big thank you to Mike100 who just send me some photos of his ex-Len Andres short rods bits and motor...

They put at last some flesh on the bones of times long gone!!!

3/4 shortened cylinder, 3/8 shortened cylinder and std -55R KR cylinder:

Image

3/4 cylinder exhaust port clearance:

Image

2 different methods to reweld the cylinders, 3/8 on top, 3/4 on bottom:

Image

Image

Patrick

Post Sun Oct 31, 2010 3:43 am
jib

Posts: 575
Location: devon,england
never having seen the valve reliefs in a kr cylinder ,would anyone care to post some pictures please,regards jib
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Sun Oct 31, 2010 4:31 am

Posts: 587
Location: Crewe, Great Britain

Hi Jib,

Bigger JPG of my avatar:

Image

That's the rear cylinder from Mert Lawwill 1965 KR/KRTT, period Pohlman factory shot... They went for even more reliefs/sinking later on...

Patrick

Post Sun Oct 31, 2010 4:56 am
jib

Posts: 575
Location: devon,england
thank you patrick, awesome picture, me thinks the kh needs some polishing up :roll: :roll: :lol:
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Sun Nov 14, 2010 12:47 pm

Posts: 919
Location: RENO,NV. U.S.A.
I read this post when it first came out and just reread it a few minutes ago. I hate to burst anyone's bubble,but K's,KH's,KHK's,KR's have NEVER used head gaskets on any engine at any time,in fact none of the "R" engines ever used a head gasket. As the proud owner of TWO XR1000's I can attest to that. BREWSKI

Post Sun Nov 14, 2010 1:32 pm
jib

Posts: 575
Location: devon,england
brewski ,what happened to the alloy k model barrels you were making??

were you referring to the 'potato chip' remark that panic said. I really think he meant the''' barrel to head interface'' commonly known as the gasket surface, rather than inferring that k models had a gasket as such.

regards jib
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Thu Nov 18, 2010 6:50 pm

Posts: 919
Location: RENO,NV. U.S.A.
JIB,there is another production run of cylinders scheduled for the end of January. Keep in touch ,for further info. BREWSKI

Post Thu Nov 18, 2010 6:58 pm
jib

Posts: 575
Location: devon,england
BREWSKI wrote:
JIB,there is another production run of cylinders scheduled for the end of January. Keep in touch ,for further info. BREWSKI


brewski . how about some pictures of the first run? and some comments of those that have used them...

or are they top secret and like a certain ladys bottom.....
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

Post Sat Nov 20, 2010 3:46 pm

Posts: 2685
Location: Los Angeles, CA
David Jackson of San Antonio bought a couple truckloads of K stuff a few years ago. There was both K and KR parts. In this load were a couple sets of KR short cylinders. He tells me that they were factory items and showed no sign of brazing or having been shortened outside the MoCo.

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