July 26, 2010 – My younger brother, Joe, is the “mechanic” in the family. He started riding my 1953 ex sidecar racer around Philadelphia in 1964, about the time I got hitched. I stored the bike there one fall and he had the keys to the garage. Needless to say, it got a lot of miles on it I didn’t authorize. He ended “doing penance” and rebuilding the bike for sale after blowing it up. The “blow up” story is instructive…
My 1953 Zundapp KS601 started out as an un-titled “shop racer” for Victor Pannetti, an Italian motorcycle enthusiast/racer/mechanic/dealer who, by the time I met him, was the owner of a thriving import motorcycle business in Milwaukee, WI. Vic had been a Zundapp dealer, getting his stock from Butler and Smith in Hasbrouck Heights, NJ. I spent a good part of the summer in 1962 as an hourly employee in his shop and used the time and income to advantage in my subsequent purchase of the 1953 KS601. I owned and rode it as primary transportation from 1962 to 1964 when I got married and then on-and off as a recreational/second car until it was converted into cash that helped fund my last resident semester in undergraduate school in 1965-6.
I had a good friend, “Doc” Phinney who was a year or two ahead of me in college but who shared an interest in model aircraft and who grew up / worked in Milwaukee. “Doc” worked for Vic in 1961 and purchased the KS601 from Vic for $350.00 and a “parts guarantee” which was a handshake deal. Doc was told that if the bike needed anything while he was still working for Vic, and Vic had it in stock, Doc could use it off the shelf. Doc was extremely excited over his new bike and decided to show it off and test it out over the fourth of July week-end in the summer of 1961. I was working as a lifeguard and small craft instructor for the Kellog Foundation school camp north of battle creek then known as “Clear Lake Camp.” Doc showed up on the bike, all the way from Milwaukee with Wisconsin papers in his pocket and a couple of police “stops” for no license plates in Indiana and Michigan due to the fact that back then in Wisconsin you could carry temporary papers with you on the bike until your state plates came in the mail. We rode around on it all week-end, two up. It had a great after market Pagusa covered bolt on spring and shock damped passenger saddle which placed the rider’s face above the driver in the slipstream. The saddle had a big rubber-covered “D” ring handle with a grease fitting in the middle for the swivel joint of the seat which gave it the shock absorbing capacity the short travel heavy springed “plunger” rear on the early KS 601’s lacked. It had two screw clamps which fit the stock luggage rack side slots perfectly, locking it in place above the luggage rack. It could be removed with an 11 mm wrench in less than 30 seconds! At the end of the holiday week-end, Doc had to be back at Vic’s in Milwaukee, and I had a new batch of campers coming in for swimming lessons, etc. Doc took off on Sunday afternoon headed west on brand new I-94 out of Battle Creek. Somewhere between Battle Creek and the Michigan border, I’m not sure where, Doc decided to “see how fast” his new bike would go. I-94 was so new that sections didn’t even have the white line painted on the concrete yet! At any rate, Doc claimed he saw the far side of 110 on the original Zundapp speedometer before starting to back off. At somewhere between 90 and 80, the piston on the left hand side collapsed and was shattered into the crankcase by the flailing connecting rod before he could get the clutch fully disengaged. He coasted to a stop, luckily without having the bike “sieze up” and throw him to the pavement. A couple of “test kicks” confirmed absolutely no compression on the left side.
Doc pushed the approximately 500 lb bike over a mile to the first exit ramp and rolled it down the ramp to a gas station at the foot of the ramp which was open with a single attendant. There he proceeded to unpack his meager tools and dig deeper into the problem. The oil pan was removed and it was full of piston chunks and the oil-pick-up line connection to the screw on oil screen/filter was completely sheared off by a piston chunk or a piece of cylinder skirt driven by the connecting rod base through the line. The right-hand side still had compression and seemed intact except for a chip out of the cylinder skirt. Doc proceeded to scavenge a piece of brass tubing from the shop floor and was able to pound it into place to serve as an oil pick-up. He cleaned everything out of the pan the best he could, unbolted the bent left side connecting rod and completely removed it and both left side pushrods from the left cylinder. Then he rolled up a bunch of rags and stuffed them into the badly scored/cracked left jug and filled the bike back up with “drain oil” salvaged from the gas station. A couple of kick start attempts were rewarded, and he was able to fire the bike up on “one lung” and keep it running with the throttle. That was good enough for him. He found out where the nearest railroad depot took “casual freight” and ended up driving the bike 18 miles on half an engine, signing it onto “casual freight” for delivery to downtown Milwaukee, and got on a train to get home to be at work the first work day after the 4th of July holiday. A week later, the bike was picked up using the shop pick-up truck and taken back from the downtown train depot.
Vic, it turned out, was true to his word. Doc installed two new pistons with new rings, replaced the left Cylinder with a new one, installed a brand new connecting rod, wrist pin, etc. on the left and put the bike back on the road “as good as new.” He may have even replaced the left cylinder head. I forget now. Even though that bike had been sidecar raced from 1953 through 1958 or so, the cast iron cylinder that was not replaced on the right side. It mic’d out as “new” and had no serious flaws or scoring from the ordeal. A small chip had been broken off the lower cylinder skirt but that was deemed “good enough” to keep the cylinder in service. In the process, Doc went through everything. The valves were lightly polished and re-seated, the valve guides were checked and possibly very lightly “knurled” to insure a perfect fit, the clutch was rebuilt, etc., etc. When Doc bought the bike, it came with a custom built racing sidecar and 32 mm Del’Orto racing carburetors. Doc had taken the racing carbs off and re-installed the brand new, never used Bings that came with the bike as part of the prep for his trip to see me. He ended up selling the carburetors and the sidecar for almost enough to cover his original purchase. With the parts guarantee, he made out like a bandit, and by extension, when I bought the bike from Doc so he could use the money to finance a brand new 1959 Ariel Square Four Vic had stashed in his attic and still had in the shipping crate back in 1962, so did I.
In the early spring of 1965, some 60 or 70km later, my brother Joe decided to hop on the bike and bring it west to me in Yellow Springs, Ohio where I was in my senior year of undergraduate school. He didn’t know enough about air cooled engines at the time and was too cheap to change the oil or did not know it was supposed to be SAE 20 in winter. Unfortunately, I had put it away in the fall with summer weight SAE 40 or 50 in the crankcase. He drove it a bit that winter and then started out the last week in March for Yellow Springs. He chose a bad week-end for the trip. Shortly after leaving Philadelphia, a cold front blew in and the temperature dropped to Zero and below. He limped from rest-stop Howard Johnston to rest-stop Howard Johnston clear across the Pennsylvania Turnpike to Pittsburgh in that cold, stayed overnight with a family friend, and started out the next day, in still near or below zero temperatures. Coming down along a gradual grade out of Wheeling W. Va. on old US 40, the same left hand cylinder ate another piston. Luckily, he got enough warning to pinch the clutch before the piston failure was quite as serious as the first one. I got a phone call that he was stranded with a blown motor. It was the first I knew he was on his way. We rented a trailer, piled into my 1953 Ford Crown Vic with a plexiglass sunroof, and hauled ass east to rescue him. By the time we got to him, we were in a raging blizzard. On the trip back, the bike was not very well strapped to the trailer. It was exciting, to say the least. I was driving with four people in the car and a loaded trailer behind me. We were in a raging wet snowstorm on four lane US 40 west of Columbus, OH when I ended up losing control of the car. We went whipping 360 degrees around on the concrete two lane west and off into the center grass taking out a sign and cracking boards in the trailer with the bike. We spent over half an hour rocking the vehicle back out of the ditch with all four of us pushing, re-loaded and re-tied everything, and crept home in the storm soaking wet, cold, and miserable. I never got my damage deposit back from the trailer guy.
Resurrecting the 1953 from that second piston failure was much more challenging, in part due to poverty and in part due to the already miserable available parts supply for the now orphan Zundapp KS 601. We eventually found two pistons, but they didn’t quite match in geometry or weight. Both had the original five ring configuration and came with new rings. The left jug was slightly scored but not enough to warrant going 10 thousandths over, and the right one was still nominal after all it had been through. We ended up doing “hillbilly dis-service” to the anonymous next owner. The two pistons were placed on a balance that had also been used to weigh out ounces and kilos of the local herb. The exact balance in weight was re-established by using epoxy to attach a nickel to the center of the top of the lighter piston, and the bike was re-assembled slightly out of balance with respect to compression ratios. Road tests I did gave me little impression that the vibration levels had changed. Before the overhaul, I used to “show off” by starting that bike with the kick starter using one hand to push it through. It would “pop” the first time it went through a compression stroke and then sit there with a absolutely rock solid 300 rpm idle. After the rebuild, in part because the rings had not fully re-seated, it usually took a strenuous kick or two, but the compression resistance was actually lower and we left the idle a little higher. I never met the guy who bought it.
The summer I worked for Vic Pannetti, I actually learned more about resurrecting pan heads and WW II Harley 45 cubic inch bikes than I did about the Zundapp KS601. This was primarily because when I got it, it was in perfect condition. All I did to maintain it was follow the “book” oil change regime and keep the valves adjusted to tolerances I learned “by feel” from Doc and the lead mechanic working for Vic. I always carried a small tool kit that would allow me to deal with plugs, valve clearances, change oil, and do tire maintenance. The bike went through a pair of good quality 350 by Continental tires about every 20,000 miles the way I used it. Approximately every 5,000 miles, the bike was jacked up on the center stand, steadied with a couple of concrete blocks under the jugs, and the wheels rotated. I had this procedure down to about a half hour start to finish including unpacking and repacking the needed tools. I kept all “working” bolts free of corrosion and easy to open/close using a small tube of stuff I remember as “Anti-Seize” lubricant. I still have a can of it. It worked great on the big bolt which secured the original equipment “came with the bike” crash bars to the frame at the steering head. It kept the rocker box covers easy to drop off for valve adjustments. In my tool kit was an old “mini-grease gun” which was used to hit all the grease nipples on the bike after each oil change. I pumped the grease hard enough for it to flow out around the “to be greased” fitting locations to be wiped off with a clean shop rag. Because the 1953 had been sidecar raced for so many years before it was put back on the road as a touring bike by Doc, the transmission had received a maintenance pass under his stewardship. The effort replaced the 1st to 2nd gear shifting dog and the 2nd gear drive gear. Vic was very knowledgeable about this process and probably supervised the work. Because of its’ racing use, Vic had a complete stock of available gears for ratios which might give the machine the slight edge needed to be a winner instead of an also-ran. The transmission on the bike when I used it had a very nice set of sweet spots for acceleration and tooling down the road. The camshaft may have been machined for improved performance over the stock Kardan Sport configuration which came out of the factory because that bike was strong and fast.
My favorite cruising speed was between 62 and 65 on the speedometer in fourth with the manual spark fully advanced. On one trip, scrupulously keeping track of mileage, I got up to about 65 mpg during sustained cruising. If I wanted to pass at that speed, I would double clutch down to 3rd gear and wind the motor up to my passing speed, up to almost 100 mph if I wanted that much. I had an old home made fiberglass “Wixom” style faring with very heavy support hardware which came with the bike and which was removed every spring and re-installed when it got cold around Thanksgiving. This cut winter mileage 10 mpg or more. From the time I first drove the bike until I lost track of it, another “trick” was part of the routine. Every tank fill of gas was sweetened with about an ounce of top cylinder lubricant. Even back in the early 1960’s my KS 601 lived on unleaded gas. I would spring for “high test” when ratting around with other bikers, but on long distance tours, settled for regular with no appreciable differences in performance or mileage. We felt that unleaded gas reduced deposits that built up on the spark plugs and might have been an issue for valve guides, etc., etc. That 1953 Kardan Sport Model which had been set up for racing never used a drop of oil. The design from Ferdinand Porsche for top cylinder lubrication included a slight “bleed” from the upper cam sump down though the push rod oil pump system and through the exhaust valve guide into the top of the cylinder. Unfortunately, the valve guide tolerances were “too good” and without the top cylinder lubricant, there was some risk of the kinds of failures we experienced with the five ring pistons. The left hand side of the motor is closer to the front of the bike and may naturally tend to get a little less oil pressure from the lubrication system or run hotter. On that bike, the right rocker boxes always filled up first after an oil change. Because each crankcase was an individual lost wax sand casting and manually machined to tolerances, it is very likely that some bikes might have been “ever so slightly off” with respect to the way the cylinders bolted onto the cases. This initial variation could have contributed to the failures we experienced, but my best hypothesis is that a deficiency of top cylinder lubrication tended to increase friction of the upper two piston rings enough to eventually induce metal fatigue in the aluminum. When this got bad enough and there were severe stresses like “backing off” from a sustained acceleration, the piston could literally come apart at the ring groove and collapse.
That KS 601 may have had one other “custom” transmission repair. Back in those days around Milwaukee, it was relatively easy to find a machinist who could make a gear based only on a sample to copy. I’ve subsequently learned that a lot of Zundapp KS601’s had/have a fiber ratchet gear associated with the kick-starter mechanism. These fiber gears will break down and “wear out” faster than the more important gears in the transmission minimizing potential repair costs. Unfortunately, it is difficult nowadays to do what Vic probably did early on in the service life of that bike. The kick starter ratchet gear was re-made out of a more durable metal stock material than the fiber gears. I had forgotten about that issue until my most recent local KS601 sighting. I got a phone call from a guy living in the same township who had taken his recently acquired Canadian sourced Zundapp KS601 to the local artisan vintage BMW mechanic here in Ann Arbor, MI. Kevin told him about me and he called me up to “take a look” at his bike. It had been sitting for some time, long enough for things to “dry out” above the normal level in the transmission. We had some trouble getting the kick starter ratchet to engage properly and it “got stuck.” I instinctively rocked the transmission back and forth via the back wheel a couple of times and tried it again. It worked fine afterwards for the two or three kicks I gave it. I told the guys to “get the bike running” and after the transmission had been thoroughly “stirred up” change the fluids and give it a more leisurely diagnostic period before tearing into the gears to see how bad the ratchet gear was worn.