The January, 1972 issue of Dirt Bike Magazine featured a comparison test between a Maico 501 and a Husky 500 Twin. The bikes were examples of extreme engineering but never really designed to be compared or even compete against each other. The Maico was a production bike, but the Husqvarna was prototype concept machine, never seriously slated for production. The exact Husqvarna used for this test still exists today in the Tom White Early Years of Motocross collection. Here is the test, as written in 1972.

In January, 1972, Dirt Bike opened its second volume with the Maico/Husky comparison.

There are motorcycles, then there are motorcycles. Picture, if you will, a mount that has more power than you could ever use under any condition. A crack of the throttle produces not just a surge of acceleration, but an arm-wrenching, violent, neck-snapping leap forward. 

These are the super bikes. Both have more power than any rider will ever use under normal racing conditions. The European motocross champions will not use them for racing, claiming the smaller mounts are more than enough. Ake Jonnson uses the 501 Maico before the start of a season to get in shape rapidly. After spending a month or so on the 501, he says the 400 feels wonderful and completely tractable. 

The 500 Husky Twin has been around for a few years, but none of the top-line riders have expressed a desire to campaign one of the’ brutes. These, then, are monster bikes. Why do they exist? Who can use them effectively? What are they really like? Read on. 


When the 500 Husky Twin is first fired up, everyone present draws a quick breath. The bike flat sounds mean. Rather than the normal two-stroke bark, the exhaust emits a howling, ear-splitting sound much like a road racer. Sort of like an 8,000-pound wolf in a bad mood. The sound is so exciting, the hair on your neck stands on end. And you just know the bike is ungodly fast. It is a cold-blooded beast–not at all easy to start when the bike has been sitting for any length of time. Warm, it presents no problem. It takes a long time to warm up to proper operating temperature, and refuses to run clean until good and hot. 

Initial impressions when straddling the bike are mixed. It doesn’t feel much different from a 400 Husky, except at the middle. Here, the fins stick out from the oversized tank and the exhaust pipe hits the inside of the rider’s thigh. 

Leaning the bike over to one side while at rest, one can notice the extra weight. But it is not objectionably heavy. Most of the weight is down low and slightly forward. 

The box has the old-fashioned long throw, and engagement of low gear must be a deliberate movement. Down for low, release the clutch gingerly–and the bike will more than likely stall. It dawns quickly: the bike is not a torquer. One must buzz the engine and slip the clutch slightly to get under way. 

Once the machine is moving, hang on. Things happen quickly–so quickly, that the first ride gives most riders the shakes and trembles. 

Right around 4000 rpm, all hell breaks loose, and the motorcycle turns into a wheel-spinning freak. Even in straight-line acceleration, the bike fishtails violently from the incredible power output. One learns to roll the throttle on, rather than snap it on. 

The engine never seems to run out of revs. A shift to the next gear brings more of the same fantastic surge. Things happen suddenly on the Husky. On one long sweeper, Jim Connolly, hooking it strongly in third gear, goosed the throttle a hair too much. The bike got completely sideways and stayed that way for about 20 yards. 

Later, when questioned about the maneuver, Jim said, “Man, when it got crossed up, all I could think about doing was give it more throttle to keep from high-siding. That damn bike just never seemed to run out of R’s. It kept accelerating sideways as fast as most bikes do straight forward. It was scary. That’s a white-knuckle machine.” 

IF THE RIDER allows the machine to fall off the power band, it blubbers and loads up. Most of this problem, according to the Husky people, is caused by the lack of a still air chamber and the restrictive characteristics of the two sock-type filters. A trip to the next lower gear normally brings the revs back up. 

Failure to keep it running clean means going through the old Amal carb routine. While the engine is blubbering, the rider has to turn off the gas tap, hold the throttle wide open, wait for the engine to clear and then quickly re-open the gas tap before the float bowl gets dry. 

The big Husky can be started in second gear, but it is a tricky process. 

The best way to accomplish this is to wind the twin up to near peak revs, put the weight as far forward as possible and feed the clutch out smoothly but quickly. The motorcycle hesitates fractionally, then starts to pull like a freight train. It will quite literally dig a trench in the ground. The engine pulls long and strong in second gear, and a clean shift to third keeps the blast going. By the time third gear peaks out, the landscape is blurred and the bike is approaching roughly 70 miles per hour. And still one gear to go. 

The suspension is soft; just the right ticket for long cross-country races. TT riders would no doubt want a firmer ride. The Husky Twin is not intended for motocross use; it has too much power, all of it concentrated in the wrong place for MX use. Grand Prix races, Baja 1000, Mint 400 and races of that ilk are the Husky’s forte. Most riders agreed that the machine could be a sterling TT bike, but only for the seasoned expert with cat reflexes. The mighty double-engined Husky runs the same clutch as the 250 Husky, and they’ve had absolutely nothing in the way of problems with the clutch. This says something for that particular clutch design.

THE WHOLE ENGINE is basically two 250 engines put together with a handmade crankcase. The cylinders, heads, pistons etc., are regular 250. The cranks and the rods are also standard items. The cranks receive some machining and are then pressed together. This method works out quite well, and no crank flex or twisting has been experienced. Carburetion is by a pair of Amal concentrics, not because they are the total answer, but for the simple reason of size. They’re squat enough to allow installation without any exotic machining or special adaptors. 

Our test bike was shod with a 4.00 x 18 Barum on the rear, although it can carry a 4.50 with no modifications needed. The Husky had been run at Elsinore with a 4.50, and even though it was new when installed, it was completely worn out at the end of the race. 

The engine was not new, by anyone’s yardstick . . . it was first run in the Mexican 1000 by Gunnar Neilson, and then it was at the Mint 400. After these biggies, it saw action at various desert races. To cap it off, Claus Neillson rode it in the Greenhorn Enduro. 

It has been incredibly reliable for a prototype. Other than normal maintenance (rings, plugs, etc.), no problems have been experienced. 

Electrics, borrowed from a Bosch snowmobile unit, were modified to fit the Husky crank. It was installed in the 67-68 season, mainly because it had an excellent lighting system. This was needed because the Husky was to be campaigned extensively in cross-country events like the Baja and the Mint. 

Rear shocks are the standard Girling units found on all Huskys. Our test bike had 60/90 progessive springs–pretty much garden variety stuff. Front suspension is stock also, using either 20- or 30-weight oil, depending on course condition and rider weight. 

The expansion chamber is basically a 400 chamber, using 250 bits and pieces. Much cutting and rewelding was necessary to tuck it in. Two pipes exit the engine and join over the head, then route out the side. The heat shield is ineffective, and all riders mentioned burning sensations on the left leg. The chamber was developed on the dyno for maximum usable horsepower and is very critical to even the smallest changes. 

WHILE ON THE dyno, maximum horsepower was read at over 60 hp at the crank. More ponies are available (who needs it?) by merely going a tad radical on the porting. To date, there have been no requests for increased power from the riders. 

The frame is basically a normal Husky frame. It has parts from MG and MI frames which, for all practical purposes, are identical. The wheelbase has been lengthened over a stock frame for two reasons: First, the engine is bigger, and more physical room was needed. Second, Gunnar Neilson, who did much of the development work, likes longer frames. Even his motocross bikes are on the long side. 

Adding to the long wheelbase is an altered head angle. This again, is at Neilson’s request. Both of these factors add up to a fairly slow- reacting bike and a predictable one. This is almost a necessity for something like the Mexican 1000, and makes high-speed riding a little easier. The tape revealed a 55-inch wheelbase, with perhaps another inch left in reserve take up. 

The gearbox is a regular 400 Husky gearbox, but the shifting mechanism is the older hardware used prior to 1969. It has a very long throw, which could be easily corrected with one of the new shifting kits. No one has gotten around to doing this yet. 

Tentative production is slated for summer or fall of ’72. No price has been set as of this date. The Twin will be produced in limited quantities, Enduro tank was held in place by strap. so don’t expect to see them right alongside the 400 on your dealer’s floor. A good guess would be 1,500 to 1,700 bucks. 

Whether the Twin will be produced in any great quantities will depend on the success of the initial batch of machines. If it ever is released in large numbers, there are a lot of horsepower-happy dudes who are going to buy one and get scared to death in the process. 

If any bike in the world is NOT for the novice rider, it’s this one. It will get away from 90 percent of the riders in the world today. The other 10 percent will know better, but will lie awake at nights saying, “Gotta get me one of them monster bikes. Gotta get it.” 

501 MAlCO 

Even though both bikes are over-powered animals, they have distinctly different personalitieties. Whereas the Husky is pipey, the Maico is a torquer. The machine has enough low-end power to plow the south 40. The big-barreled 501 comes on from idle like a double-A fuel dragster and pulls straight through the power range. 

The most apt description would be that it has more low-end than a 400 Husky and more mid-range and top-end power than a 400 Maico. Our test bike had a wide ratio gear box, but still could make second-gear starts like most bikes do in low. Acceleration would make your socks roll up and down. Everything was right now. No hesitation. No stuttering. Wham! Instant power at any rpm. If you have ever ridden a 400 Maico, the 501 should make you feel right at home. It shares the identical frame and suspension. A casual observer would not notice the difference between the two bikes until he got close and looked at the huge barrel and head. This unit pokes out from under the gas tank on both sides and completely fills up the space from the tank to the frame tubes. There’s not much room left over.

Starting the big single is no problem. A compression release is installed in the barre, and the engine will run quite happily with the release open. One easy prod when warm (two or three when cold), and the 501 rips into life. 

The noise is deafening. The sound is much like a number of shotgun blasts intermittently going off. Blip the throttle, and the sound goes from a bang-bang-bang to the throatiest rap in the business. 

Clutch in, down for low on the left side, and you’re rolling. When cold, the clutch does not release completely, but this disappears after the bike has been run for a few minutes. The 501 can be putted around at near zero revs with absolutely no complaint, tempting one to think, “Hell, it’s not all that fierce.”

THE FUN STARTS after the engine is warmed and the throttle is stretched. The power surge starts immediately, and the rider’s arms are straining to keep him forward in the saddle. You know–you just know–that if you slide back on the seat, the front end will go up in the air. Low gear winds out a long way, with a slight gap to second gear. The revs drop, but the engine pulls just as strongly as if it was on full honk. More of the same in second, with third being slightly closer on the gap and then a large jump to fourth. 

This is where the flat torque curve really works. Even though the jump to fourth is large, the damn thing keeps on pulling like there’s no tomorrow. If you can find enough room to peak fourth gear out, you will be approaching 90. With dirt gearing. 

As long as straight-line acceleration is the ticket, most riders will be able to get it on. The problem comes at the end of those straights, where, usually there is a corner of some sort. Here the surplus of power becomes a genuine handful. The rider must use discretion or he will be in deep trouble. 

One of the test riders owned a 400 Maico and knew his normal elapsed time around a test course. When mounted on the 501, he put in a number of hot laps, under the watchful eye of the stopwatch. After the ride, he came in, slightly breathless, and said, “Hey, I was really gettin’ it on out there. That thing is so fast I can’t believe it. What was my time around the a course?” 

When informed that his time was 1.4 seconds slower per lap than with his 400, a look of disbelief spread on his face. Additional attempts on the course backed up the initial clocking. 

Even though he was going like Jack the Bear on many sections, he was also fighting the bike a great deal in the turns. Correction after correction was required to keep the 501 on its intended line. 

This was not caused by any handling defect, as the 400 chassis is well-proven. The machine simply had more beans than could be used. Instead of putting the power to the ground, much forward motion was lost in useless wheelspin. 

ON MOST MOTOCROSS courses, third gear will handle any situation, except for tight hairpins; second gear does the job on these. A rider can let the revs drop to almost nothing, then snap the throttle open to be rewarded with a catapult-like thrust. The bike had better be in the correct .attitude when the throttle is opened or the Maico will swap ends. 

Handling is impeccable, helped in part by the healthy 55-inch wheelbase. The 501 will track, slide or square off a corner equally well. The most efficient way through any corner seems to be accomplished by making use of any existing berm. 

Like the 500 Husky, the 501 Maico is not intended for motocross use, even though some riders are competing with them. It is primarily designed for competing in the Open class in American AMA racing. The rules stated that the machines must be over 500 cc’s and this the Maico is. Its secondary purpose is that of competing in Grand Prix, TT’s and special events where the accent is on horsepower. 

Right now, Cooper Motors is developing a 501 for half-mile use, and they already have as much horsepower as the hot 650s. All that remains: sorting out the handling and changing the frame for the special half-mile requirements. Should be interesting, as the bike will weigh appreciably less than anything being run. 

Bits and pieces are roughly the same as the 400 Maico (see October, 1971 , DIRT BIKE), but some things bear mentioning. 

The bike still comes equipped with a paper filter and an air hose that will allow dirt to pass. The standard filter should be replaced before the bike is started for the first time, and the air hose must receive some sort of sealant and hose clamp. 

Most of the fiberglass on the bike is strong enough, but the seat on our test machine showed cracks in its base after three days of riding. This definitely needs reinforcement. Overall finish of the glass components is decidedly poor, but the motorcycle looks good anyway. It presents a very business-like appearance, as any true racing machine should. 

THINGS FELL OFF the big Maico with alarming frequency. The rider who owns one will have to put in some time on maintenance. Every nut and bolt on the motorcycle must be checked after every race. Failure to do this means trouble. The motor mounts, in particular, must be checked closely. We lost six motor-mount bolts during two weeks of testing. The engine is mounted in place with three bolts, but we neglected to keep that close eye on them, and consequently spent a great deal of time hunting through the old tool box for something that would fit. If any one of the mounts become the least bit loose, the rider will know rather soon. Vibration will become so bad that the hands become numb and much of the engine’s power is lost. We would really like to see a few more mounting positions standard on the 501. Three are simply not enough. 

The 501 also experienced the same chain-rubbing habits of the 400. Even when properly adjusted, the chain will graze the swingarm cross strut and start carving away metal at a slow, sure pace. The rider would be wise to protect this contact area with something-even if it’s only a few strands of safety wire to act as a buffer. 

One must realize that the 501 is a total racing machine, and must be treated accordingly. Indifferent maintenance will insure its destruction. This is not a motorcycle that one just hoses off on Sunday afternoon and rides the next weekend. If kept in a razor-sharp state of tune, the engine is virtually bulletproof. The rod is hefty and the bearings generous. Massive fins keep the engine cool, but contribute somewhat to the weight. The Maico engine, less carb, weighs in at 82 pounds, with oil in the gearbox.

While being a “‘bit easier to ride than the Husky,” it is still not a mount for the casual rider. If you are one of those gifted dudes with cat reflexes–maybe. But very few are. 


In a flat-out drag race on the starting line of the Saddleback MX course, the Husky was the fastest of the two, but only marginally. On level hard ground, it was a tossup, the winner being the rider who got the best traction. The surplus of power in both machines determines the winner on two counts: Rider skill and pure guts. 

The Maico handles better overall and is a lighter bike. The Husky would seem to be the choice for cross-country competition. The Maico is a natural for TT and Grand Prix riding. Neither bike is a motocrosser, but the 501 can be raced in motocross if discretion is used. 

Both machines are overkill in the power department, so it is with a great deal of awe that we must report the following fact: Sitting on a dyno bench in the Maico factory is a 6l9cc single engine. There are no plans as of this writing for the engine to ever be introduced . . . still, it’s there. 

And rumors have it that some engineers at Husqvarna are considering two larger engines grafted together, just as an experiment. 

Just picture an 8l0cc twin Husky on the starting line! Sorta takes the old breath away. Now if we could just get Maico to make an engine using two 619cc singles in the same 

Frame . . .

The Maico 501-Husky 500 comparison as it appeared in 1971

PRICE: Suggested retail, approx. $1478.00 
Engine type: Piston Port, 2-stroke, single 
Displacement: 501cc 
Bore and Stroke: 91.6 x 76 
Compression Ratio: 12: 1 
Carburetion: 36mm Center Float Bing 
HP @ RPM: Claimed: 54 – Actual: N/ A 
Clutch: Multi-plate in oil 
Primary Drive: Duplex Chain 
Final Drive: Single Row Chain 
Gear Ratios: 1-2.78: 1 
Air Filtration: Paper element 
Electrical System: Magneto 
Lubrication: Oil mist in fuel 
Recommended Fuel: Premium 
Recommended Oil: Castrol 
Fuel Capacity: 2 Gal. 
Frame: Tubular, double loop 
Front: Special MX 7″ travel 
Rear: Girling 60/90 spring 
Tires: Front: 3.00 x 21 
Rear: 4.50 x 18 
Wheels: Front Special spring steel 
Rear: Steel 
Wheelbase: 56″ 
Ground Clearance: 81/4″, Seat Height 
Weight: Claimed: Dry 238, Actual: 242 
Instruments: None 
Brakes: Front: Single Leading full width 
_ Rear: Single Leading Conical 
Pounds per Horsepower
(actual roadweight) 


PRICE: Suggested retail, approx. NA 
Engine type: Piston Port, 2-stroke, twin 
Displacement: 490cc 
Bore and Stroke: 69.5 x 64.5 
Compression Ratio: 12.3 : 1 
Carburetion: Amals IVa/l, 2 
HP @ RPM: Claimed: 60, Actual: NA 
Clutch: Multi-plate in oil – 250 clutch 
Primary Drive: Straight cut gear 
Final Drive: Chain 
Gear Ratios: ‘1-2.36:1 
Air Filtration: Filtron Socks 
Electrical System: 
Bosch Snowmobile, modified 
Lubrication: Oil mist in fuel – 20:1 
Recommended Fuel: Premium leaded 
Recommended Oil: Bean oil 
Fuel Capacity: 3.9 Gal. 
Frame: Tubular single loop 
Front: Husqvarna telescopic forks 
Rear: Girling 60/90 spring 
Tires: Front: 3.00 x 21 
Rear: 4.50 x 18 
Wheels: Front: Steel 
Rear: Alloy 
Wheelbase: 553,4/1 
Ground Clearance: 91/2/1 
Seat Height: 32/1 
Weight: Claimed: NA 
Actual: 260-265 dry 
Instruments: None 
Brakes: Front: Single Leading Conical 
Rear: Single Leading Conical 
Pounds per Horsepower 
(actual roadweight) 4.9 per hp 

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