Last of the classic Flatheads
Henry N. Manney III
Old racing bikes tend to stir different emotions in the eyes or minds of the beho1der, even if he may never have seen that particular machine in action. Modern man, used to die-cast aluminum multi-cylinders, probably will react with indifference to a brakeless Cyclone board-tracker, remark Cor look at all those external pipes to the storied 120 deg. Twin Moto-Guzzi, turn his nose up at a classic camshaft Velocette as old-fashioned and simply not appreciate the difference between a GP Triumph and a newer Bonneville, not that there really is much externally.
A Harley KR. however, will always draw a crowd of silent onlookers in spite of being not all that special designwise, about as graceful as a safe and every inch a dinosaur. Why? The KR is very much a proper racing machine and demands respect, even as the sullen silver Auto-Union V-12 set men to musing what sort of person could manage to drive this device to its utmost?
Constant readers of Cycle World (advt) may remember our October issue in which we skipped fleetingly over Harley history and noted, in passing, that the flathead 45 cu.in.V-Twin WL made its appearance right after the Kaiser War and lasted, with the same bore and stroke (2.75 x 3.81 in.) up into the middle Fifties. That is to say the WL production flathead, which earned a swing arm chassis (and became the K series) in 1952, went on to an enlargement to 55 cu. in. three years later and in turn was given ohv (see XL) in 1957. For reasons known only to God, Harley and the AMA, in that order, the flathead formula was retained for racing and the flathead WR, a logical name, became the flathead racing KR, with rear suspension and in that form ran a nyway through 1969 at least. Needless to say there was a certain amount of development, mostly empirical, over the 30-plus years to transform a mundane sidevalver into the King of the Dirt Tracks. An information handbook-c*mshop manual that Harley doled out to purchasers of its racing bikes is full of information garnered over 40 years of cut and try and is the stuff of which racing is made. The same empirical approach was rather less successful when a road-racing team was fielded as Harley seemed to forget the fastball that got it to the World Series and threw up a lot of cute junk. The party wasn’t actually over, at least on dirt, but the flathead design had just about come to the end of the line.
The subject of our Salon is an ex-works bike that was ridden in 1969 (and possibly earlier) by Haaby and Reiman, the latter doing the honors at the rain-delayed 1969 Daytona. Departing from tradition with the lowboy springer frame designed by St. Louis Harley dealer Earl Widman and sporting an Airhart spot brake on the rear, the KR RR along with others on the team (barring one WR) had had the benefit of head rework plus domed pistons via a single-cylinder mockup in Harley’s racing shop during the winter. Unfortunately the mods didn’t turn out too well, carburetion being all over the lot, and Reiman was crafty enough to whip the cylinders, heads and probably pistons off his dirt-tracker and fit them at the last minute. Unfortunately for him the clutch went away (at least that’s his story) and the KR retired. Due to our lack of back issues, I can’t follow up how the bike did the rest of the year but in time it was sold to Buddy Stubbs in Texas (winner Novice 1966) who planned to go racing again and didn’t, eventually selling it to celebrated restorer Steve Wright whose arm we twisted for this Salon. It says a lot for Mr. Wright that not only did he consent to trust his precious vehicle to the hands of our tester Mr. Eagan at Riverside Raceway but also furnished all sorts of useful background information.
Taken at face value, the AMA formula of that time (which meant 500cc ohv vs 750cc sidevalve) had worked out to be reasonably equitable. The English competition was getting a bit long in the tooth, while the Japanese menace was still casting shadows before itself in the form of 500cc Kaws or Suzukis plus a mixed lot of 250 and 350cc Yamahas. There wasn’t all that much reason, therefore, for Harley to go to pieces (the fastest, Rayborn’s, was 5 mph down on 1968’s Daytona time and 6 mph down on DuHamel’s best 350 Yamaha mark for this 1969 practice) except for those streaks of racing luck that afflict even the greatest from time to time. As it turned out, the monsoon came, washing out the event for a week and possibly giving Milwaukee a chance to get its act together as the classic Rayborn won at slightly over 100 mph, followed by Grant (Suz), Duff (Yam), Lawwill (HD), Gould (Yam) and Markel (HD). Haaby finished his KR 10th, Reiman dnf as related earlier, and I suppose only the HD factory knows which one of those two bikes is our Salon subject. I think Steve was told that eight only of these road racers were made and like most factory “ specials” is a bit different from the norm, nothing unusual when apparently none of the Harley runners at Daytona ’69 were absolutely identical. Judging by previous models, the most obvious differences were the spot rear brake, a separate Tillotson diaphragm carb for each cylinder and on some of the Harleys a megaphone exhaust system which, in the case of ours, has been reconstructed by Mr. Wright as the original had gone missing. Not showing is all the careful polishing work inside to make sure that all the oil speedily gets back to the lowest point, more detailing to make sure that said oil doesn’t puddle there, endless hours of fudging about with roller bearings plus shafts fitting therein, days of lapping in the gears with a light abrasive followed by total disassembly and cleaning out. More hours delicately setting the oil pump and breather to operate just so, another day or two cutting the cam off its stub shaft, setting the timing exactly then welding it on another shaft, doing it again after picking the wrong cam, grinding away at the roller tappets reducing friction, chamfering the pistons, reinforcing the intake manifold, seating the valves just so, and making sure that the head shape, with its funny steps and shelves, matches the latest factory manual. These factory documents are full of useful (i.e. empirical) information such as leaving x thou above the intake valve but y thou above the exhaust (the valves are anything but tulip, having almost a right angle between stem and head) but as Mr. Editor Girdler observed, tuners who really know their job don’t need the factory bulletin. It breathes, however, a word from the past when it says Upon No Account remove the film of carbon from the piston crown or a loss of power will result. Flatheads are funny.
Harley's KR750, and Why You Shouldn't Change It When It Works
Assorted useful bits of information include a wheelbase of 54 in., 355 lb. dry weight approx., 18 in. wheels (3.00 front, 3.50 back although 3.50 f 3.25 b slicks are on it now), compression ratio probably around 6.5:1 with domed pistons fitted, four speeds (choice of 4 sets of gb ratios), horizontal magneto, head gasket via aluminum paint, clearance piston-cylinder head 0.035-0.040 in., ignition timing with Fairbanks-Morse magneto 38 deg. BTC on the front cylinder, oil pump turns lA engine speed, etc. Plugs I think were Champion N54R and there is a book on adjusting those Tillotsons. There were two camshaft sets listed for the KR and the KR-TT; tappets clearances for both are a lot less than those used for the XLR, which may explain why the ohv sounds like that. Don’t say you never learned anything technical! The handbook is also a mine of information about how to set up end play in the transmission, rebuild the bottom end, shim the valves so they don’t hit, and make you properly respectful of Dick O’Brien and his merry men not to mention all the privateers who rebuilt it in a dirt infield between races. And that’s only the beginning, as the trick lads start with all the above and probably have a different arrangement for every race. Since 1920 you learn something.
So what’s it like? Starting the KR is rather a dodgy proposition as the massive Tillotsons, bearing a reputation for being diabolical anyway, don’t seem to have proper float bowls let alone a choke and thus require liberal applications of Easy Start plus a lot of pushing. Then it is dot carry dot dot carry dot carry erk which usually means a change of plugs although using the warmer N60R might obviate some of that. Anyway after a few tries in that vein, the venerable flathead decides to keep going (possibly the fuel lines looping down under the carbs have something to do with this) and with Steve up disappeared around the corner still going d.c., the other cylinder joining in at intervals.
Eventually they came back in full song, the staggered Harley beat bringing the mechanics of a nearby Can-Am car over on the run, and then I got to sit on it and go Woomph woomph w hile Steve bled the oil pump. Apparently Harley recommends that the oil be changed every time the bike is run (!) which means cleaning out the 5 qt. oil tank below the seat, draining the oil cooler under the tailfeathers, blowing out the lines and then bleeding the bleeding pump to get rid of any airlocks hiding inside. Anyway it was rather like sitting on a water heater, all fat and warm, going woomph up to three thou and actually I would have taken a tour around (on soft plugs) if anyone had asked as the CG is quite lowand the whole business feels anything but flimsy. Of course the bars seem only an inch across, the grips are so big that the ends of your fingers scarcely touch and (although the tank and seat are adjustable fore and aft) the riding position jockey-style with knees up would be a little difficult, not to mention the R.H. shift being upside down and backwards. Perhaps it is just as well.
Considering the usual behavior of racing machinery, the KR really doesn’t make much mechanical noise . . . perhaps after San Jose it would sound different . . . and it reminded me of those competition Ferrari V12 coupes that go diggadiggadigga in a fiendish fashion but every digga is under control, readily identifiable and doing something useful. Under way with Our Pat aboard it seemed to be turning easily enough, giving out its characteristic flat exhaust note and sounding way overgeared although in fact it had pretty short ratios, topping out before the end of the long straight. Mr. Eagan also reported that the bike was very steady and solid, barring the occasions when he grounded the bottom trumpet, yet was quite responsive to input from the handlebars. As one would expect, the engine was a bit of a shaker but not particularly cammy, even there was little response below 4 thou racing wise, especially after backing off for a corner. Cough cough hack hack and then “good power” would come in approximately at 4800, he would shift at 6 plus or minus, then carry on to 68 or thereabouts at which point it is producing near its 55 bhp. With new parts, the fast boys probably turn a bit over 7 which is pretty remarkable in terms of side valves and the elevated piston speed of 4500 ft./min. Clutch worked easily with light pressure, gearbox shifted nicely, rear brake retardation wasn’t noticeable, front brake tended to tighten up on its own as it got the linings hot. The engine smoked a bit (figures of 1 gal. oil for 100 miles are casually tossed about) but conversely was well-mannered and quiet enough so that Eagan didn’t even need his earplugs. Isn’t that nice? A Gentleman’s Racer. Style in every line. They don’t make them like that no more.
