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KR crank options?

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45Brit

Posts: 1453

Joined: Tue Nov 27, 2007 2:29 am

Post Fri Jan 18, 2008 2:34 pm

Re: KR crank options?

no, I can see what you are saying, but I don't think you are quite asking the right questions.

I've been following this thread for no other reason than that I am an engineer by profession, and find it interesting. To me the sequence is;

1) what have I got now - answer, no crank at all

2) what will physically fit into the available space? - answer, see thread

3) is it available? - answer, see thread

4) is it available at an acceptable cost? - answer, see thread

5) what is the bike for, and hence, what characteristics do I require?

6) what characteristics do the available parts offer?

I would suspect that by the time you have answered 2, 3 and 4 there aren't actually many options available. Don't forget also that flywheel diameter affects other things as well ( cf Patrick's point about affecting the scavenging )and I certainly wouldn't go machining down flywheels without a clear idea of what I was trying to achieve
Shoot, a man could have a good weekend in Dallas with all that stuff...
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thefrenchowl

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Location: Crewe, Great Britain

Post Fri Jan 18, 2008 3:14 pm

Re: KR crank options?

Hi all,

Another way to look at it: the lighter weight of the KR flywheels is that it might have everything to do with the fact that the -55R KR/XLR rods are WAY more weighty than the K/XL rods!!! To redress and end up with a similar full assembled "ideal" crank weight, probably arrived at by trial and error, the factory might have thought lighter wheels were the order of the day.

Another point worth considering is that a lot of period flat track riders, but not all of them, did not like one bit the big -55R rods and went for XL rods and wheels when they rebuilt their engines... Something to do with the cost of rebuilt, the higher reciprocating weight, the speed of rollers???... I don't really know but it's a period fact...

Also, 45Brit, I tend to not modify things willy-nelly, I've only got one KHK engine, it's rare and I don't want to end up blowing it to smitherins... Which is why I tend to look at what's been done in the past while loads of talented tuners went about their business making the KR, then the XR into good racers...

Some mods, like relieving the side of the pistons or the dome experiment were only attempted once and for a short period, hence I can read in that it wasn't a success... So I won't even consider experimenting with that.

Other mods, like twin carb and profound relieving have shown to be worth doing cause a lot of tuners did it, so the law of average tells me it's OK to try!!!

I also won't tell somebody else to experiment for me, hence, what I write is what I've done... So, Slindo, if I tell you go for the XL crank route, I've done it and it works, I'm even surprised at myself, the KHK's been running on that crank and twin Linkert DC for 2 years, about 4000 miles at nearly full throttle, not to mention the tractor WICO 4 cyl magneto modified to H-D 2 cyl firing... did not have to call the road side rescue assistance yet!!!

Patrick
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45Brit

Posts: 1453

Joined: Tue Nov 27, 2007 2:29 am

Post Fri Jan 18, 2008 3:54 pm

Re: KR crank options?

I'm puzzled by your reply, Patrick.. As far as I can see, the only mod you are talking about, is turning the wheels down by a very small amount for clearance and oil drag reasons. I've sen that done many times on a range of old engines, for the same reasons and with similar results.

someone else is writing about flywheel weights, and doesn't appear to understand the design questions inherent in what he is saying, ie that the distribution of the weight is also important ( cf comments about rod assembly weights )

I am suugesting that in fact he is pursuing a blind alley by concerning himself with flywheel weights, to which you appear to be replying that you have an engine which works very well with stock components.. which is what I expected the answer to prove to be
Shoot, a man could have a good weekend in Dallas with all that stuff...
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thefrenchowl

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Location: Crewe, Great Britain

Post Fri Jan 18, 2008 4:53 pm

Re: KR crank options?

Hi 45Brit,

I was just trying to say that KR crank ASSEMBLY is probably the same weight as a K or XL assembly!!! The comment on skimming the flywheel is to do with HD making 4 strokes but building cranks and crankcases like if they were for a 2 stroke!!!

Slindo,

I know it's hard to make decisions when you don't feel you have all the facts... Forum doesn't help either as everybody comes in and tell you this or that. In the end, it's your KR engine and, either you unload it to somebody else, pay big dollar to have it redone by a 3rd party, or do it yourself, but you and you only will have to make and take these decisions. In your own mind, you've got to take responsability and choose your own route to solve the problems you'll encounter as you go. If you think crank choice is hard, wait till you start assembling this engine!!! Every nut in there will have you questionning your own sanity... Most of these KR engine will have had their internals AND externals moded this way or that way by umpteen different guys over their life, it's like REAL education and there's probably not one STD KR engine out there. I got my KHK in 1987, it fired for the 1st time in 1991 cause I had loads to learn and my enthusiasm did not make time go any faster... You've got to be prepared for the long run...

Patrick
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mike100m

Posts: 51

Joined: Fri Jul 23, 2004 12:01 am

Location: felton,Ca.USA

Post Fri Jan 18, 2008 7:54 pm

Re: KR crank options?

Patrick
Do you know of a source for the #2 Torrington. In my search of bearing houses it appears it is an obsolete size from Torrington.
Mike


thefrenchowl wrote:Hi panic,

As I said, 52/53 KR had the WR type crankshafts in it, so your dimms might relate to these earlier thin on the ground KR motors.

What I know for sure is that my XLRTT, restamped motor, probably made in 1960, is all metric, stated metric sizes which were the same as KR and it was bought in Wisconsin!!!

I also have the factory drg for ball bearing gear box sprocket rather than loose rollers, dated 1958, it says to use the drive side crank bearing, 9030R, dimms in inch as follows which translate in 25 x 52 x 15!!! : shaft .9839, OD bore 2"0476... The 9 cam ball bearings (2 of them in the magneto iddler gear) are also metric, 9 x 24 x 7, the only one bearing that might still be inch is the Torrington needle roller that can replace the #2 cam big bush in the timing cover.

My spacer set up uses all the std street bits: oil seal and carrier, sprocket, only the shafts are ground down to 25mm.

Patrick
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mike100m

Posts: 51

Joined: Fri Jul 23, 2004 12:01 am

Location: felton,Ca.USA

Post Fri Jan 18, 2008 8:18 pm

Re: KR crank options?

I just weighed a pair of KR flywheels bare no shafts. 16 lbs. Casting # 56R.
Mike
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slindo

Posts: 66

Joined: Tue Jan 08, 2008 7:25 pm

Post Fri Jan 18, 2008 9:02 pm

Re: KR crank options?

What are you, a troublemaker? We've already established that they are not! And couldn't be. And even if they were it wouldn't matter.

Seriously though, many thanks. Always nice to have an infusion of cold measureable fact when speculation starts getting out of hand.

Do you have the rods handy? It would be interesting to have a weight for them too.


mike100m wrote:I just weighed a pair of KR flywheels bare no shafts. 16 lbs. Casting # 56R.
Mike
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slindo

Posts: 66

Joined: Tue Jan 08, 2008 7:25 pm

Post Fri Jan 18, 2008 9:11 pm

Re: KR crank options?

Have you tried E.B. Atmus in Springfield, Mass (not far from the site of the late lamented Wigwam)? They are great at finding oddball stuff and have been able to get me, over the years, many bearings that the other shops had never even heard of.

mike100m wrote:Do you know of a source for the #2 Torrington. In my search of bearing houses it appears it is an obsolete size from Torrington.
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45Brit

Posts: 1453

Joined: Tue Nov 27, 2007 2:29 am

Post Sat Jan 19, 2008 12:29 am

Re: KR crank options?

Patrick... that's what I had understood you to be saying, that the complete assembly was about the same weight, but the particular components varied, in different versions.

I take it that your comment about 2-stroke cranks for 4-strokes is a reference to the crankcase / flywheel clearance and hence the skimmed wheels. Lots of old 4-strokes are like that. I don't know about H-D, but a number of early 30s British designs such as the Blue Star BSA, Panther singles and some Royal Enfields relied on crankshaft oil fling to get the oli around the scavenge pump, or back into a front-mounted wet sump, hence the very tight clearances, and the feature was just carried forwards for many years afterwards because no-one thought to change it.

That's one reason you sometimes see early Gold Stars with case failure - the oil locks between the flywheel and the case. Later ones are slightly different, just as you describe. There are other reasons that Goldies break their cases, though!!


I know what you mean about there being no standard KRs anywhere, ha ha. I don't know KRs but I have a fair amount of experience of racing JAP singles, and they are about the same.

There are umpteen variants; a 350cc, four main versions of the 500cc such as long and short con-rods and different numbers of head bolts; long-stroke and short-stroke 500cc versions - note that the stroke and con-rod variants are not the same. The differing con-rod lengths are to change the power characteristics by varying the crank geometry and rod angles during the powerstroke.

Most of the main sub-assemblies more-or-less fit together to give several other possible combinations, most of which require irreversible alteration to main components ( eg ultra-short-stroke 500cc using 350cc crank, oversize 500cc using long-stroke crank and short-stroke barrel, 350cc engines with oversize ports using 500cc inlet valves, welded cases to give later 4-stud top ends on earlier 5-stud cases, about the only one you DON'T see is a possible oversize 350cc using 500cc parts; this is because the scrutineer would spot it straight away and either disqualify it, or put it in the next class up against full 500cc engines - no good! Plus quite a lot of the ones now running use late-model 84S parts for reasons of availability )

I do have a 'three-two-five' BSA engine in my workshop, ie a 250cc BSA C15 using a 71mm Triumph piston; this gives abou 325cc, hence the name, and is visually the same as the original.. but we won't go ino that.... they were quite common at one time!
Shoot, a man could have a good weekend in Dallas with all that stuff...
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XLH59

Posts: 4

Joined: Sat Nov 10, 2007 12:45 pm

Post Sat Jan 19, 2008 3:01 am

Re: KR crank options?

to make information complete .... the plain rods weight (without bearings, cages and crankpin) is 2.4 lbs or 1.08 kg ...

.... of course it is always nice to have and use original parts, but if you see what thoose ironhead drag racers do with their stock crank you can be sure that technically it is good enough for lots of power ....

ralf
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mike100m

Posts: 51

Joined: Fri Jul 23, 2004 12:01 am

Location: felton,Ca.USA

Post Sat Jan 19, 2008 1:24 pm

Re: KR crank options?

Inner and outer rods, 2lbs 2oz. Complete rod assembly, rods, pin (w/nuts), rollers and cages, 4 lbs.
Mike




slindo wrote:What are you, a troublemaker? We've already established that they are not! And couldn't be. And even if they were it wouldn't matter.

Seriously though, many thanks. Always nice to have an infusion of cold measureable fact when speculation starts getting out of hand.

Do you have the rods handy? It would be interesting to have a weight for them too.


mike100m wrote:I just weighed a pair of KR flywheels bare no shafts. 16 lbs. Casting # 56R.
Mike
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panic

Post Sat Jan 19, 2008 6:39 pm

Re: KR crank options?

Sorry, my mistake. I'll try to be more careful.

If I don't say anything, am I still wrong?
Last edited by panic on Sat Jan 19, 2008 9:52 pm, edited 2 times in total.
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mike100m

Posts: 51

Joined: Fri Jul 23, 2004 12:01 am

Location: felton,Ca.USA

Post Sat Jan 19, 2008 9:22 pm

Re: KR crank options?

Panic
As you stated, larger pin more bearing area. The larger rollers have more surface area which spreads the load over a larger contact area on the pin and the races. Also the larger rollers turn slower and are exposed to a larger volume of oil which keeps things cooler which makes the oils job a lot easier by giving it more load surface to work on. 5/16 rollers slower speed is also easier on the cages which have larger surfaces where they contact the rollers.
But then HD has gone to a 2" pin with 1/4" rollers on the XR but I believe that was to get a more rigid crank assembly as they made their way to 100HP.
What do you mean by change direction?
Mike


panic wrote:I'm not sure what the factory was thinking of when they went to the big rod set.
1. no length difference, so it has no effect on breathing, etc.
2. no change in taper size, so it doesn't affect lock-up, rigidity, etc.
3. the larger big end obviously adds to the rotating weight of the wheels, so (if the intent was to maintain inertia at the 1954 level) weight would have been removed from the halves
4. the small end looks considerably heavier than the previous 1953-54 KR pair (WR without the lightening holes), and even than the K/KH pair, so vibration may have been worse.
Perhaps they didn't yet have any confidence in the 1954 pin & 1952-54 rods (K, KH?)?
I would assume they intended the larger bearing area to be an advantage for long races (were they experiencing failures with the 1939-54 54 × 3/16" rollers?), but I don't think their planning was on target - the new 51 × 5/16" rollers only give slightly more effective area, and have much higher inertia both as the the weight of each roller in the cages, and of the bearing assembly in the rods. This tends to make the roller refuse to change direction and skid - very bad.
More than 1 engineer suggested to me that the obvious choice would be the same rod (if that's what they wanted, or to save re-tooling), but with a larger 1-3/4" pin, and 72 of the old 3/16" rollers for 41% more area.
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XLH59

Posts: 4

Joined: Sat Nov 10, 2007 12:45 pm

Post Sun Jan 20, 2008 3:17 am

Re: KR crank options?

KR rods and crankpin at ebay:

item --- 330205708467
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slindo

Posts: 66

Joined: Tue Jan 08, 2008 7:25 pm

Post Fri Jan 25, 2008 9:21 am

Re: KR crank options?

I just heard from S&S again, and the WR/KR flywheels weigh 18 lbs. Which makes them lighter than normal K/XL flywheels, which seem to weigh around 20 and change, but heavier than real KR wheels, which several people have reported as weighing 16. So they would appear to be "real" racing flywheels, if maybe more WR than KR, and not just slightly modified XL stuff as some have suggested.

In the interests of making this thread as complete as possible, it would be interesting to know what a set of DLD flywheels weigh. According to Girdler, they were often used on the WRs, and when the KR first came out with the original unsatisfactory crank Len Andres tried using a pair of 1929 DLD wheels in the KR, and found it made it so peaky and abrupt that it was very hard to maintain traction.

BTW, someone on this thread accused me of being unaware of other design considerations, such as distribution of weight. This is not true at all - I have all along made it clear that weight is just one of a number of factors. But you got to keep in mind that there is only so much room in that very tight crankcase to fit a flywheel. Certain hunks of metal have to be in certain places, to accept the shafts, to give adquate stiffness, and to counterbalance the rods and pistion. So there is only so much you can do to fiddle the distribution of weight. Sure (as Panic said, but seems to have deleted) a ten pound flywheel can produce just as much momentum as a 20 lb one - but not in a KR case!
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Payton

Posts: 56

Joined: Fri Aug 31, 2007 8:31 am

Location: Central Fl.

Post Fri Jan 25, 2008 11:43 am

Re: KR crank options?

The Frenchowl aka Patrick wrote:

If you really need a crank, as I said, easiest, less painful, less cost is to go for a 57/70 CH complete crank, I mean rods, flywheels, shafts, sprocket... Panic's right in saying there is a street 30 teeth one, but it's the K/KH, and to use that, you'll have to weld it on its holder and get rid of the cush drive. 34 teeth CH ones have not this problem, they are one piece, without cush drive.

///////////////////////////////////////////////////////////////////////////////////////////////////////////////


I have a one piece 30 teeth sprocket that fits the XL sprocket shaft and it is listed in the parts book for the 54 and early 55 KH.

I also have the 34 teeth XL sprocket which is one piece.,
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thefrenchowl

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Post Fri Jan 25, 2008 11:54 am

Re: KR crank options?

??? Payton,

Give me the part number of that 30 teeth one piece sprocket, it's not in any of my 3 K factory parts books...

Patrick
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Payton

Posts: 56

Joined: Fri Aug 31, 2007 8:31 am

Location: Central Fl.

Post Fri Jan 25, 2008 12:14 pm

Re: KR crank options?

Patrick:

52 to 56 parts manual for k models, and 55 to 65 manual. Part no, is 40238-54, and a solid sprocket is shown in a
diagram.



Payton
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panic

Post Fri Jan 25, 2008 2:46 pm

Re: KR crank options?

Yes, I deleted it.
You appear to ask questions, but already know what answers you will accept - making any new information rather pointless.
However: again, you're comparing flywheels as if dead weight was a valid basis to determine anything except the postage cost to ship them.
Until you examine them you have no idea whatever which of those is "heavier" (i.e. more stored inertia).
I don't know Mr. Girdler, but granting your quote accurate and complete and crediting him with all the facts - using a DLD flywheel will have several effects:
1. IIRC the diameter is smaller, which will reduce the inertia a great deal (this is a typical H-D mistake, also made on the 1st VL and EL).
2. another reason is that the scraper clearance is now too loose - and this is before Sifton figured out how to make these engines live under sustained hard throttle (including installing a ring upside-down), but more oil was considered a good thing at the time.
3. he may have done the reader a disservice by not mentioning that the DLD wheels have no oil pressure to the crank-pin. Potentially cured by drilling; he evidently didn't think that was important.

Re: "so peaky and abrupt that it was very hard to maintain traction"
Yes, about what I would expect. However, although accurate, this is also subject to misinterpretation.
The engine was not peaky because of the reduced inertia. The peaky power curve is a result of the cams, intake port size etc. and with heavy wheels the transition from low power and complete traction to high power with reduced but still good traction was easy to ride. Light wheels caused traction to vanish when the motor cam up on its torque curve, and less controllable. Same effect as a wet road.
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thefrenchowl

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Post Fri Jan 25, 2008 4:39 pm

Re: KR crank options?

Hi Payton... Learn something new everyday, that's the real youth elexir!!!

Gosh, have had that catalogue since 1986 and never noticed that... Weird!!! My 54 KHK originally had the KH type compensating sprocket and knowing it's different from the K one, I can only assume H-D got rid of the K one and gone for cushionless drive for the time it took to design the new ramps as I notice the KH std sprocket is a 55 item??? These 30 teeth one piece sprockets must be very rare indeed!!!

Panic,

"abrupt" is the word I was looking for when describing the Munch Mammoth behaviour, that's related to low inertia. For a given power/capacity, there must be an "ideal" flywheel assembly weight to make it tractable and usable, even for racers...

Although I must be grateful to Allan Girdler for his personal introduction to myself of Pohlman isoteria all these years ago, I must add his books are more like long magazine articles, full of their flaws, scant regard for real detective work, too much trivia accorded history status without triple checking the facts...

On the oil subject, it has always amazed me that H-D stood alone for a long time in thinking its racers needed LESS oil circulation than the street counterparts, despite the much harsher environment, K vs KR, XL vs XR, and ran them with 1/4 speed oil pumps... Wet sumping being the culprit I suppose, so they thought less oil in there was the better of two evils..

Patrick
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