| THE BIGGEST TWO-STROKE SINGLE EVER MADE! THE LEGENDARY HERE’S WHAT IT WAS REALLY LIKE By Rick Sieman | ||||||||||||||||
FORWARD: After more than 30 years as a moto-journalist, few stories have stirred moreinterest than the legendary Maico 760. I had the opportunity to actually race one of thesebeasts in the 1981 Blackwater 100 race, so I can speak with a measure of authority as tohow this unique machine really was. In fact, when I crawled off the 760 Maico after the Blackwater 100, beat half to deathfrom the brute power and the brutal course, a friend asked me a question:
"Would you ever go back and try the Blackwater race again on a 760 now that youknow what it’s like?" My answer: "No. Not right now, But maybe in a month or so, when the terror startsto fade and I can sleep a full night without waking up in a cold sweat, I mightreconsider. But I have learned my lesson. No more 760 Maicos. That just doesn’t makeany sense. In fact, I’ve already called the Maico factory to arrange for an 840 Maicofor next year. After all, the 920 isn’t ready yet!" Note: For those who want the full, gory, muddy, sloppy, slippery ugly story of theBlackwater race with the 760, you can get it in my book, Monkey Butt, which is availablethrough Off-Road.com. For some reason, the email has increased expressing interest in the Maico 760. So, tosatisfy the curious vintage bike historians out there, here’s the test from almost 20years ago. *** Right up front, let’s admit there is no valid reason for this bike to exist. Noone in his (or her) right mind needs a 760cc motorcycle for the dirt.Least of all, a 760, two-stroke single.
Everyone knows they can’t work, right? And everyone also knows that the lighter,smaller bikes usually turn the fastest lap times at many tracks. So why does a 760 Maicoeven exist in the first place? Consider it a noble experiment, if you will. The Maico engineers are a proud, arrogantlot and they love to do things people say simply cannot be done. For example, just a fewyears ago they made a single-cylinder 125cc road racer that gave the Yamaha twins absolutefits. The FIM made a special class for bikes used in ISDT competition having over 750cc indisplacement; this class was dominated by the huge BMW twins. In 1978, Maico decided theycould do the Beemers one better and the 760 Maico was born. They fielded a team of tall,strong, German riders and proceeded to get gold medals right and left. The bikes wereincredibly reliable and reportedly easy to ride. Still, that was all conjecture, as no one outside of a factory rider had ever slung aleg over one of the beasts. Admittedly, I had a somewhat morbid curiosity and madearrangements to acquire one of the bikes for a test. The basis for the test was when I actually entered and rode the fearedBlackwater astride one of the 760s. As luck—and the elements— would have it, Iran out of gas repeatedly and was lucky to finish the grueling event before winter set in.Lack of preparation and endless peat bogs had us well into an advanced state of wheelspinand tree smashing. However, I was left with deep and lasting impressions of the 760. Enough so that I hadthe bike shipped out to California and put it through the more-or-less normal testsequence. ATTENTION GRABBER First off, you must understand that the 760 draws crowds wherever it goes. At Davis,West Virginia, we had a constant stream of folks walking by and studying the big animal.All of them shook their heads in amazement and many of them asked questions. The samequestions that we’ll attempt to answer in this test, such as it is.
Probably the most commonly asked question was: "Is it fast?" Yes, but not like any Open bike you might be familiar with. It doesn’t explode andlurch off the line, doing wheelstands all over the place. No sir. It merely pulls like thefriendliest tractor you ever did see in your whole life. The bike peaks out at a mere 4000 rpm. In this day and age of Open bikes turning7000-plus rpm, it’s almost leisurely. Peak horsepower is rated at a very conservative43. However, at a mere 1200 rpm, the massive engine puts out 26 horsepower, more than thehottest 125s produce at peak revs. And we’re talking rear wheel horsepower, too. Noneof those namby-pamby readings at the crank. Now, think for a moment about those numbers and try to translate them into some sort ofreality in your head. It means that the rider can loaf down the trail at just above idleand, with a flick of the wrist, have a big bucket of torque at his disposal. No radicalrpm needed. Just roll that sucker on a little bit and get a lot of forward motion inreturn. To try and give you a good idea of what this feels like, think about the following fora moment. The Blackwater race was held in quite possibly the nastiest conditionsimaginable. Deep bogs, tight woods, water crossings of death, etc. Grim. Some of thesections threaded through narrow tree-lined paths, with slippery roots criss-crossing thetrails.
Here, the 760 could be comfortably left in third gear, with no clutch work required. We could let the rpms drop off to almost nothing and smoothly roll the throttle on; thebike would respond by pulling strongly, with no snatching or grabbing. Almost like a Huskyautomatic, but with none of the irritating lag and hesitation. Long uphills were almost a joke. Just leave the bike in third or fourth and roll thethrottle on as needed. No down gearing or clutch slipping needed. This was truly the onlydirt bike we’ve ever ridden that never ran out of power, no matter how low the enginewas forced to lug and grunt. The closest thing to a tractor imaginable. The second most asked question was: "Is it a bear to ride? Must be a real handful,right?" No. Actually, the bike was incredibly easy to ride. The power delivery was as flat asany stretch of Kansas landscape you can picture. It literally pulled from idle. Now, weknow that’s a widely overused phrase, one that journalists like to pull out of theireditorial hat to "dazzle the spectators." However, in this case, it holds trueright down to the gnat’s buttocks. You can chug the 760 right down to the last few wheezes and it’ll pull backwithout a hint of protest. There are no odd surges or sudden bursts of power. Rather,there’s a smooth, steady and seemingly endless flow of vibration-free torque.Combined with the heavy flywheels, there’s almost no wheelspin. The meaty Metzeler onthe bike simply hooks up and pushes the bike forward with no fuss. NO SHAKES... NO BREAKS
You might well wonder how they get a single-cylinder engine of this size to run withoutvibrating itself to death. Simple. The crank is balanced as if the engine would turn themore-or-less normal 7000 rpm. But, with the power peaking at 4000, the engine never evengets into the shaking range. In fact, it puts out less vibration than a mildly tuned 250play bike. This leads one to ponder a few things. For example, if the big 760 were allowed to runup there in the high rpm range, what kind of horsepower would it turn? The Maico engineersfelt 65 to 70 horsepower at the rear wheel was not out of the ballpark. A small drawback is encountered, though, if the 760 is allowed to breathe fully.It’ll shear conventional frame tubes in a rather short time. When the engine isallowed to spin to its max, the vibration level becomes unmanageable. No gearbox willtolerate that load for long, and the conventional Maico primary chain drive becomesgrossly over-stressed. The stock Maico clutch will turn into a stack of Doritos under 70ponies. Thus, the deliberate detuning is not only desirable, but necessary. When one considers that a normal 490 Maico can handle a solid 50 horsepower to the rearwheel for a season, with no hassle, then the rather mild 43 horses on the 760 will seemwell within sensible boundaries THINGS PECULIAR TO THE BEAST
With the stock 2.5-gallon motocross tank in place, the 760 only managed 15 miles beforeit was sucking wind through the float bowl. Of course, our race test was conducted undersome pretty gruesome circumstances: the Blackwater 100. Here, the deep mud had us spinningthe rear wheel a great deal. Under normal conditions, 25 to 28 miles can be squeezed outof the stock gas tank. Six Days riders all used larger tanks but still could not manage50-miles range. Fortunately, gas areas are plentiful at a Six Days.
Oddly enough, the 760 could not be kickstarted when cold. It had to be push-started.Then, after the bike was warmed up, it could be fired as easily as a well-tuned 250. Noamount of choking or priming would let the 760 get lit when cold, though. While the bigbike could be booted through without using the compression release, it was not thehot ticket. One bite back and the kickstarter could be instantly sheared off. Withoutusing the compression release, a 150-pound man could literally stand onthe lever and it wouldn’t move through its arc. Obviously, lots of gas is wasted as it passes through the combustion chamber. Maybethat’s just nature’s way of telling us that perhaps a 760 single doesn’tmake much sense. It was necessary to jet the huge engine on the rich side, just short ofblubbering, to get sufficient fuel, and there was still some detonation and pinging underheavy loads. Maico assured us that the detonation would not hurt the engine — that itwas just a characteristic quirk of the bike. TECHNICAL TRIVIA The 760 runs a normal 490 rod and crank and uses a 250 gearbox to transfer the power. Astandard clutch is also used. It held up well for us, with no slippage at all. This speakshighly of the basic Maico drive train.
Our test machine used a standard 1981 Mega 2 chassis, with no enduro or ISDT hardwareattached. This gave us a bike that weighed just about 10 pounds more than a stock 490. Notbad. After putting in some time on the bike, we started referring to it as "thetwo-stroke that feels like a four-stroke." The piston measures a mammoth 107.52mm across and is derived from a Porsche industrialengine, then highly modified. The piston skirts are deeply cut and the slug itself israther light for something that big. No doubt the lightness also helps to keep thevibration down. A single dykes ring does all the sealing. Ring end gap and piston clearance are critical on the 760, because expansion must beconsidered. A careful setup will yield a reliable engine, while one set up a fraction tootightly will wear out rapidly. A loose engine will invariably crack skirts and getterrible mileage and performance. Clearly, the 760 is not for Joe Lunch-box. CAN I GET ONE? No. So don’t ask your friendly local dealer. In fact, there are only three of the760s in existence. We were pleased to be able to get our hands on one. This year (1981),there will be no more over-750cc classes in the ISDE, so the Maico monsters will berelegated to the factory museum. The factory has no plans to market any version of the 760. They’re candid enoughto admit that the 400 or 490 can do anything that the 760 could, with less attendanthassle. In retrospect, the 760 was simply made to prove a point and to garner some GoldMedals in Six Days Competition, to keep Maico in the limelight. Well, they did all that and a little bit more. They made some history. The largesttwo-stroke single in the history of motorcycles was not only built, but run, successfullyin world competition. They had fun, proved a point and left their mark. It was an honor and a genuine thrill to take the last ride on that warhorse before itwas put out to pasture. SPECIFICATIONS - MAICO MEGA 760 PHOTO CAPTIONS (maico1, 4.c photo) The authorspent considerable time extracting the big 760 from deep mud in the Blackwater 100 race. (maico2) Massive fins wereactually almost two inches wider on each side than the old 501 barrel which the top end isbased on. Weight difference between the two engines? The 760 was only nine pounds heavier. (maico3) Maico East folksdelivered the 760 for the race and hung around to help with pit stops after dialing thebike in. That’s Gary Herto with the cowboy hat. (maico4) Pipe barely clears thehuge head. Horsepower was rated at only 43 at the rear wheel, but the 760 pumped at 26ponies at only 1200 rpm! That’s barely above idle. (maico5) The 760 required onlya blip of the throttle to blast out of deep sand turns. The author demonstrates at the oldIndian Dunes track. (maico6) That small (!) pistonis from a 490 Macio. The Big One is a 760 slug. (maico7) Can you guess whichhead is from the 760 and which one is from a 501? (maico7) Trivia stuff: bottomend is from a Maico 250; all other components, including suspension goodies, are straightfrom a 490. | |||||||||||||||||
