Maico 400 Motocross
MAICO 400 MOTOCROSS
CYCLE WORLD ROAD TEST
power Aplenty, lmpecçáble Suspension, And A New Clutch For Maico's Competitive Big-Bore Racer
THE 1970 INTER-AM motocross series is over, the record books stand open for inspection. Contesting only 12 of the 16 events on the calendar, Maico's Ake Jonsson piled up an almost unbelievable record of seven wins, three 2nds and one 3rd-place finish to win the 500-cc class. His teammate, Willie Bauer, finished the series in 4th place with one win, three 3rds, three 4ths, one 5th, one 6th and two 7th places to his credit.
Both of these men are champions in their own right, but they couldn’t have won without championship-caliber machinery. That same caliber machinery is offered to the private rider in the form of Maico’s potent, but tractable, 400 Motocross, a worthy successor to Maico’s popular 360, the X4-A.
STARK, SLIM, FUNCTIONAL
Starkly functional in appearance, the Maico is still one of the better finished competition machines we’ve seen. Although quite unconventional in shape, the gas tank is obviously designed with the rider in mind. Its high, slim aspect allows him to keep his knees in close to the machine, improving the standing position. Tough fiberglass fenders and airbox under the seat are styled for the same purpose and are quite substantial. Chromium plated steel wheel rims are soon to be replaced by Akront alloy units, which are reputed to be somewhat stronger, as well as lighter. Cooper Motors, the western distributor, cautions that the spokes must be kept tight to avoid breaking the hubs at the spoke Hange. In fact, Cooper includes an information sheet with each machine, which gives tips to obtain maximum performance and to preclude trouble in problem areas such as condensation in the magneto cover.
Businesslike in its appearance, the engine features a rough, sand-cast crankcase and covers, and a huge, square cylinder barrel and head. With a 77-mm bore and 83-mm stroke, the engine is definitely “undersquare” and develops its maximum power at a rather modest 6500 rpm. This engine is happiest
when pulling hard in the lower rpm ranges, and develops more power than most riders will ever be able to use properly.
The increase in engine size comes from lengthening the stroke from 76mm to 83mm, but the Mahle two-ring piston is retained. A Dykes-type top ring is used above the conventional ring to improve sealing on the downstroke and reduce ring drag on the upstroke. Needle bearings are employed at the wrist pin, and roller bearings separate the crankpin from the connecting rod. Actual swept volume is now 386cc.
Starting ease has been improved to the point where it’s absurdly easy. Maico has now moved the compression release from the front of the cylinder to the rear, but it is still located in the same relative position, '/2 in. down from the cylinder head. The engine will start and run with the release actuated. Here, again, Cooper publishes a warning against trying to start the 400 without using the compression release, as possible damage to internal engine components, as well as to the rider’s leg, could result.
A rather slow-acting throttle is installed to make it harder for the rider to get himself into trouble by “gassing it up’’ too quickly. Non-judicious use of the throttle will produce wheelspin in any gear, but the “torquey’’ power characteristics ease the job of transmitting the power to the ground somewhat.
CHOICE OF RATIOS
Two transmissions are available to suit the type of competition the machine will be used for. Our test bike was fitted with the close-ratio box which is best suited for motocross racing. Internal ratios are: 1st, 1.99:1; 2nd, 1.52:1; 3rd, 1.23:1 and 4th, 1.00:1. The wide-ratio box, which is better suited to desert racing and more general riding, has the following internal ratios: 1st, 2.78:1, 2nd, 1.79:1,3rd, 1.29:1 and 4th, 1.00:1.
Shifting is positive with relatively short pedal throw. Ball and needle bearings support the main and layshafts, and with the close ratio transmission, clutchless shifting was quite easy and relatively safe. It’s just not possible to grab for the clutch for every shift during a motocross race, and Maico’s transmission is tough enough to take it.
A new clutch, with 30 percent more lining area as a result
of larger diameter plates, is featured, and now has seven bonded neoprene plates and seven steel plates. The older clutch was somewhat lighter and had only one neoprene plate and 13 steel plates. It took a healthy grip to disengage the older unit, but the new one feels like a good road bike. Both clutches tended to drag ever so slightly when the machine was first started, but after warming up, no dragging or slipping was experienced.
DOUBLE CRADLE FRAME
Most successful motocross machines rely on a single downtube frame; AJS and Maico are two notable exceptions. Although the Maico frame is well gusscted around the steering head and employs a large loop which extends behind the upper rear suspension mounting points, the weight has been kept down to just over 21 lb. The quality of the welds is readily apparent, and one immediately notices the oblong-section transverse member to which the rear engine mounts are welded.
All controls are well arranged for a motocross machine, with the most obvious improvement over the X4-A being the kickstarter. The new unit pivots a couple of inches above the kickstarter shaft, and now swings safely past the expansion chamber and swinging arm pivot bolt. The foot pegs are low enough in relation to the seat and handlebars to allow a relaxed standing position, and yet are high enough off the ground to clear most obstacles. Riders of average height will probably find it unnecessary to alter any part of the control system, with the possible exception of the handlebars. One of our testers felt they were a little too high.
GOOD FORK TRAVEL
Suspension is half the battle in producing a successful motocross machine, and Maico seems to have it pretty well worked out. The front forks are massive alloy castings with a vertical strengthening rib cast into the leading edge of each fork leg. A healthy 7 in. of travel is provided, and rebound dampening is variable by switching SAL weights of fork oil. The rear suspension duties are handled by Girling motocross shock absorbers, with progressive 60/90 lb. springs. The lowest position provided excellent rear wheel control for our flyweight tester, and was left in the lowest position for other members of our staff as well. Although the wheelbase is now a shorter 54 in., stability is still there, even when bounding from jump to jump at less than a completely vertical aspect.
A huge expansion chamber is routed under the engine and exits on the left-hand side. A skid plate would be a good idea for desert racing, but hasn't been necessary for motocross. (The earlier X3 Maicos had an upswept exhaust pipe and chamber.) The countershaft sprocket and sidestand arc quite accessible. Although it’s the most elaborate sidestand on any motocross machine, it folds up completely out of the way and does its job very well.
POWER, AND BALANCE
Riding the Maico 400 is a thrill not soon to be forgotten. Opening the throttle only part way produces a rooster tail of dirt (or tire rubber) and helps get the front end light enough to aviate over bumps. Steering is light and precise, and the machine is so well balanced that changing the weight distribution by shifting the rider’s weight back and forth is quite effective.
Brakes are more than adequate for dirt riding and a full-floating rear brake assembly will soon be standard equipment.
Maico in Germany and Cooper Motors in California have a very close relationship. Practically every batch of Maicos incorporates subtle changes which have been suggested by Cooper, or learned in European motocross competition. Part of Cooper’s development program includes trips to C.R. Axtell’s dynomometer in Glendale. Our test machine was run on the dyno just before we received it and put out the following rear wheel horsepower figures:
The factory's claim of 42 blip C 6500 rpm at the crankshaft is well in line with Axtell's readings. The above figures are exactly what is wanted in power delivery for motocross racing.
A West Coast suggested list price of SI 287 puts the Maico 400 Motocross in a competitive price range with other machines in its class, and it certainly ranks near the top. ¡03
