KR Parts and Questions

Racing K Models

Re: KR Parts and Questions

Postby EKHKHK56 » Fri Jan 13, 2017 1:32 am

Ah very nice. No more ice cream cone shape...it melted! :D Very interesting. Well 68-69 were fast years for H-D with Cal Rayborn setting the first over 100mph Daytona in 68 and lapping the field in 69...with basically a 40 year old design. Of course Cal was extremely good at coaxing machinery to get around the track! Neat stuff, very nice to see photos of these. I have a set of 52R heads that have the standard porting. I'll dig them up to compare.
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Re: KR Parts and Questions

Postby 55panman » Fri Jan 13, 2017 1:58 am

So it kind of looks like that 60R head with the radiused combustion chamber is sort of a take off on the dome piston combustion chamber except for a flat top piston. I know I have seen a head like that before. I'll have to look, I may even have one.
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Re: KR Parts and Questions

Postby wz507 » Fri Jan 13, 2017 1:59 am

EKHKHK56 wrote:Well 68-69 were fast years for H-D with Cal Rayborn setting the first over 100mph Daytona in 68 and lapping the field in 69...with basically a 40 year old design. Of course Cal was extremely good at coaxing machinery to get around the track! Neat stuff, very nice to see photos of these. I have a set of 52R heads that have the standard porting. I'll dig them up to compare.

Yes, some remarkable speeds were attained at the meets you refer to, but I believe all this fast stuff near the end of the run was done with engines fit with the std flat type piston, not the domed piston. Patrick could fill us in for sure, but I believe the factory showed up to these meets with the wind tunnel optimized fared bikes fit with the late domed engine, and it wasn't long before the dome piston engines were sitting on the bench, due to lack of performance, having been replaced with the flat-topped piston KR engine.
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Re: KR Parts and Questions

Postby Simon » Fri Jan 13, 2017 3:01 am

I would be curious to hear Mike Sinnott's comments on this matter, as if I recall he was looking to build a dome engine. I wonder if the performance issues came more from the twin carb Tillotson setup rather than the heads/pistons?

One of the racing cylinder sets I used to have came with pop up pistons with the flame front edge beveled. Interesting to see the mods everyone tried back in the day.
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Re: KR Parts and Questions

Postby wz507 » Fri Jan 13, 2017 8:11 am

Simon wrote:One of the racing cylinder sets I used to have came with pop up pistons with the flame front edge beveled. Interesting to see the mods everyone tried back in the day.

As you note, there were likely many piston variants. One such variant was shown here in the 1965 Cycle World article where they showed Jerry Branch's preparation of a KR engine.

http://www.beautyofspeed.com/data/doc_c ... /index.htm

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Re: KR Parts and Questions

Postby Simon » Fri Jan 13, 2017 9:03 am

Indeed my parts were "said" to be ex-Branch. And I have that issue of the mag.
Interesting to see how many MR carbs modified as well! Longer intake tract?
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Re: KR Parts and Questions

Postby 55panman » Fri Jan 13, 2017 10:03 am

Back in early 2000's Bob Hoh was tuning some Harley racer stuff for Rusty (can't remember his last name) in AHRMA racing and Rusty may have even been riding one of Bob Hoh's personal KR's at Davenport vintage races. I'm pretty sure it was Bob I asked in the pits about the dome pistons and he told me that they weren't worth the trouble it was to machine the heads for them. But my memory is often suspect, so it may not have been Bob who told me that.
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Re: KR Parts and Questions

Postby starcain » Fri Jan 13, 2017 10:52 am

Very cool Cycle World article. Thanks for that. I've got a couple more questions for you guys. On the inside surface ( towards the carb ) of both the front and rear 60R heads I have there is a stamped in No. 6. Does this simply mean they are a matched set or is there some other significance to the numbers? Or no significance at all! LDB brought up the possibility that these heads were maybe not even Harley heads. I don't claim to be an expert on the matter but they look all original Harley to me. If anyone can see anything that would indicate otherwise please comment. In the 1952 to 1959 Harley-Davidson Competition Spare Parts Manual it shows a front and rear 59R head. Is this when the casting number went to 60R or is it a one year only head? Stan
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Re: KR Parts and Questions

Postby EKHKHK56 » Fri Jan 13, 2017 3:16 pm

The number stamped in W series heads like a 5 or 6 means combustion chamber size. 6 had more squish than 5. For KRs not sure but in the Jerry Branch article it says to use #7 head the latest design (1965). As far as 59 and 60 numbers in the book and on the head that's a good question. You would think they would list a 60 head if the book is newer than 60 if they were different. Could just be overlap between book and part and it's same head? My 52R heads are identical to the ones you posted. That's the design that got the work done for many years! :D
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Re: KR Parts and Questions

Postby starcain » Sun Jan 15, 2017 9:38 am

EKHKHK56 wrote:The number stamped in W series heads like a 5 or 6 means combustion chamber size. 6 had more squish than 5. For KRs not sure but in the Jerry Branch article it says to use #7 head the latest design (1965). As far as 59 and 60 numbers in the book and on the head that's a good question. You would think they would list a 60 head if the book is newer than 60 if they were different. Could just be overlap between book and part and it's same head? My 52R heads are identical to the ones you posted. That's the design that got the work done for many years! :D

Thanks for the input Erik. Since some heads are not stamped with a combustion chamber size number and some are I wonder if you could assume that the ones with a number are more specific in nature for a desired performance outcome and the ones that are not stamped with a number would be of a more generic purpose? Does that make any sense?? Patrick, any thoughts on the number stamp?
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