1953 KK Big Valves vs Small Valves

[starcain]

I'm trying to get some idea of when the KK switched from the big valve setup to the small valve one. I am hoping that you KK owners or previous owners might be able to shed some light on this subject. The parts books simply say early KK for the big valves and later KK for the smaller ones. Would like to figure out at about what motor number they made the change. My KK is a later production bike with serial number 2650 and is a small valve. If any of you guys know for sure what valves are in your KK and would be willing to post your serial number or at least the first three digits if you don't want to give the whole thing that would be great. Or if anyone has any documentation on this matter that would be way over the top great. Thanks in advance for any input.
Stan

[thefrenchowl]

Where did you get the idea early = big, late = small???

Early KK have WR valves and race keepers (factory relieved/lightened), later KK have std K valves and keepers

My 53 KK was 2253 from memory (15 years gone!!! Just checked my files, that's right...) it had the early WR set up.

Patrick

[starcain]

Patrick, The idea came from every parts book I have. Although the KK is never mentioned at all in the '53 parts book every PB after that indicates early and late for the valves. It's kind of odd that you would question where I got the idea as if it's not so and then go right on and prove the point with your explanation? Anyway thanks for your motor number. I have a friend that has a 53KK-2415 that is a small valve. A person may surmise then that somewhere between 2253 and 2415 is when the change took place. I may have an opportunity to acquire a big valve motor. By narrowing down when the change took place may help me, at least to some degree, determine if the bottom end goes with the big valve top end if in fact it actually has the big valves in it. Anyone else have a KK that could help me narrow it down any further? Any input would be greatly appreciated.
Thanks again,
Stan

[thefrenchowl]

Again, it does not say big or small in the parts catalogue...

The WR valve is a waisted stem valve like the later KR ones, the K valve is plain stem.

Cyls and heads are listed the same, so I doubt the 2 variants had different diameters.

Patrick

[starcain]

My apologies, you are correct, the parts book does not say big and small for the valves. It simply indicates 18070-41R In. and 18080-41R ex. for the early KK and 18070-52 in. and 18080-52 ex. for the later KK's. The 41-R valves were used on the WR, KR and early KK if I am correct. The assumption by many , including myself, has always been that the 41-R valves had a bigger head diameter then the standard valves. The picture in the gallery of Joe Street's KK for sale sign indicates factory installed 1 7/8" or 1.875" intake valves. An enfieldracing catalog I have offers KR valves that are 1.875" for the intake and 1.625" for the exhaust. A standard K intake is 1.703". Am I incorrect then to believe that the 41-R valves are bigger in head diameter? You are also correct in that the parts book does not mention KK specific cylinders and heads. I have no feasible explanation for that. You would think that if in fact the valves were that much bigger that they would show a KK specific cylinder so big question mark on that one. If what you are saying is correct, that there is no difference in valve head diameter between the racing valves and the standard valves and only a difference in valve stem, that would surely shake up the widely held belief that the R valves were bigger. I really hope to be able to get a look at the KK motor that I mentioned in my earlier post that is supposed to have the big valves in it. It may explain allot. In the mean time is there anyone else out there that could shed some light on this valve size issue?
Stan

[thefrenchowl]

Hi, Starcain,

I never had a standard K or KH, so can't comment too much on their valve diameter.

I did make my own stainless forged valve in the past both for my KK and KHK, with 30 degrees seats and KR flat shape but with other diims taken directly from my KK and KHK valves.

From KK to KHK, exhaust valve was reduced by 1.5mm in diameter while intake valve was enlarged by 1.5mm:

KK inlet, WR waisted type, diam 44.5mm
KK exhaust, WR waisted type, diam 41.5mm

KHK inlet, straight stem, diam 46mm
KHK exhaust,straight stem, diam 40mm

Waist part is 5/16 diam, .312, guide is .340 while stem part in guide on both KK and KHK is .339

Patrick

[starcain]

Patrick, Thanks for all your input and effort on this valve issue. In a previous post I posted a picture of a valve I picked up at the Sunshine meet in Florida this year. It was in an original box marked 18070-41R with someones writing of, Intake valve,1952 to early 1959 KR & KRTT. The box was open so I couldn't be absolutely sure that it was the right valve for the box. The valve head diameter on it is 1.752" or 44.5mm. Going by the picture of Joe Street's for sale sign picture and seeing after market valves listed with 1.875" intake valves I began to think that the WR's,KR's and earl KK's used 1 7/8" intake valves. Now I'm not so sure. After crunching and converting the numbers you have given I am back to thinking that this valve may be the correct intake valve for the early KK's. Did the KR's start out with the 1.752" intakes then go to the 1.875" in 1959 when they went to the smaller 5/16" stem? I have NOS KH intakes 18070-54 and NOS K exhaust 18080-52 which were used on the KHK. Again, when I crunch your numbers for KK to KHK valve difference, -1.5mm for exhaust and + 1.5mm for intake it comes out spot on. So from those numbers I have to believe that this valve is correct for the KK. Patrick, do you think this is the correct valve? The wasted part measures .312" and the stem .339 If there is anyone else out there that could help verify or debunk that this is an early KK intake valve it would be greatly appreciated. Patrick, thanks again for all your help.
Stan

[thefrenchowl]

One can only be sure up to a point, but my KK had only 12 000 miles when I got it and it had the WR -41R valves and keepers, so these diameters I quoted are right.

The KHK as well, it had more miles but had no signs of modifications in the valve dept.

I know it's quite fashionable to over valve and over carb bikes in the USA, so these diams you quote above are way over the top in my opinion!!!

The 55KHK I bought last year was fitted with oversized Chevrollet inlet valves as I was told here and elsewhere. They nearly fouled the pistons!!!

Not sure they are really needed in a street engine.

My 58 CH was fitted with the small valves 57 heads and the std smallish DC carb, never in me life have I seen a sweeter bike that revved like stink, even as a strocked 1100cc, 68ci, none of the mid range flatness associated with overvalved and overcarbed engines...

Patrick

[starcain]

I am a little confused as to what diameters you think are way over the top. Every number I used in my post with the exception of the 1.875 for the KR valve are your numbers. I got the 1.875 diameter from an enfieldracing catalog that has valves listed for the KR's. Not planning on using those for anything. I am just simply trying to figure out what size valves came in the early KK's. Joe Street's picture says his KK came from the factory with 1 7/8" intakes. The enfieldracing catalog shows 1.875 (1 7/8") for what I believe now is for later KR's???? I considered maybe the early KK's used that size valve but again with the numbers you provided I tend to believe now that the intakes are in fact 1.752 diameter. Patrick, I am just trying to obtain information about the early KK's. There is obviously little hard evidence out there about them and without any input from anyone, other then yourself, that has some personal experience with them the challenge will be difficult but will continue. Picture just to show aftermarket KR valves that are available.
Stan

[thefrenchowl]

1.875 is way over the top for a KR and even more so for a 900, even in the day!!!

That's probably the diameter of those Chevy valves in my 55 KHK...

But exhaust dimms listed on that ad are OK...

But such small stems will need new guides in the motor...

Whatever they think, even in AMRHA racing, they're not pushing the enveloppe like HD did then, they just don't have the budgets, and I'm pretty sure a KR fitted with such big inlets would be a pig to ride, powerband like a 2 stroke. Whatever the claims from here and there, I'm also more likely to believe the data accumulated in the real heat of the battle by the like of Axtell, Branch, Andres and O'Brien or their likes in the day. Like modern kids, mine's bigger than yours... This doesn't win number 1 plates, I can assure you...

These are my views and my facts, do whatever you wish with them, but time and time again we have been proved wrong to go bigger in whatever, valves or carb sizes...

I DO know that a side valve doesn't respond to air flow like an OHV/OHC, and that in general, big is better for SVs, but even for them, there's a limit to how slow the intake speed can be before the fuel won't mix and atomise and then burns like sh*te.

Patrick