Wednesday, June 26, 2019 | TSTM

The Evolution of the Maico 490 Engine

Square barrels, radial fins, primary chains and Bing carburetors all come to mind when you think of the Maico Marque in the 1970s. This legacy continued into the early 1980s with the release of the 1981 Maico 490 which has become one of the most famous dirt bikes of all time. You may be surprised to know however that this engine has been evolving ever since and the grandchildren are still being manufactured today.

The 1981 490 engine is not so different than engines released by Maico in the years preceding. In fact the engine is almost part for part a late 1970s Maico 440 with a much bigger hole. Just like the 440, the cylinder utilizes a large radial fin design for air cooling which was patented by Maico in 1974 (US Patent #3,782,342). This design is definitely unique, eye catching and has never been duplicated.

Inside those slim engine cases hide a three shaft transmission and a shifting plate design which is also shared with the Maico Magnum series (era 1978). Three shafts are necessary to change the direction of the engine rotation and further reduce the transmission gear ratios from the high ratio of the primary drive. The primary drive consists of two rows of individual chains which connect the crank to the clutch and forces the clutch to rotate in the same direction as the crank. The clutch itself is also an antique design that utilizes a stack of Bellevue washers to put pressure on the steel plates which are held together using metal rings.

Anyone remember what a piston port is? True, compared to its Japanese competitors the engine was seemingly dated even for 1981. However the performance, the wide power band which pulls smoothly from idle and its impeccable handling all speaks for itself. Riders spoke with their wallets and the 1981 Maico 490 might just be one of the best selling dirt bikes of all time.

In 1983 while 'Scarface' hit the box office with a bang Maico hit the ground running with the release of a radically new engine design, comparatively speaking. The chain driven primary drive was removed in favor of straight cut gears, six standard springs replaced the washer stack in the clutch, a typical shifting drum is found in the transmission and the big Maico now donned a reed valve intake. The new design was more Japanese than traditional Maico but the power and handling was all Maico. The engine's overall horse power and responsiveness was also much improved compared to the previous years.

Maico released three Maico 490 models in 1983 which were the motocross, a desert racer and an enduro. The motocross machine, also called the Spider, had a 4 speed transmission while the Sand Spider desert racer had a 5 speed. Both of these machines utilized the new engine design while the Enduro, also called the Spider E, was just the 1982 Alpha E engine with a reed valve intake.

The Spider was released with two different transmission versions. These are referred to as FK and FL gearing due to the engine serial number and the stampings on the gears themselves. The rumor is that the FK gear ratios were first released but only in limited production and later replaced with the FL gearing which has higher 3rd and 4th gear ratios. Maico must have felt the bike could use a little wider ratio and an extra 5 mph on top.

Unfortunately Maico fell on hard times this year and ultimately went bankrupt. Maico emerged under new ownership in 1984 and with the name MStar in the United States. The honey moon was short lived though as Maico/MStar also went bankrupt in 1986. None the less, the engine evolved during this time with the most significant change being the addition of liquid cooling. Although the factory started producing liquid cooled engines in 1985, they still produced air cooled versions until their departure in 1986.

Several other minor changes also occurred during this time. In 1984 the 4 speed Spider was dropped in favor of a 5 speed MX version with new gear ratios. The long standing tradition of Maico using a double sealed output shaft bearing was also replaced with an unsealed bearing and output shaft seal (ala Honda). The primary drive ratio was raised in 1985 as well as the engine to frame bolt pattern which remains the same today.

During these hard times many companies were able to obtain rights to various portions of Maico?s technology. One of these companies you may have heard of is MX-Zabel. Friedhelm Zabel started out modifying water cooled Maico 500's in the 1980s and increasing their displacements to 610cc. By the 1990s, Zabel had formed MX-Zabel and began producing 620cc and 685cc variants of the engine for side car racing. These days MX-Zabel produces a true 700cc engine and while it does not use any Maico parts some of the design still dates back to the 1983 Maico 490. Following the fall of the MStar/Maico in 1986 Lorenz Merkle picked up the pieces and began manufacturing Baby Blue Maicos in 1987. Pushing development further, in 1988 the large two-stroke received a power valve called "S.E.E.S." or "Slide Engaged Exhaust System". This is the same system which first appeared on the MStar/Maico 250 in 1986.

S.E.E.S. consists of a slide which automatically slides up and down based on exhaust pressure. This differs from most Japanese power valves which are more akin to a centrifugal clutch. Those designs use a mechanical attachment on the primary drive which moves the valve open based on engine RPMs.

Since 1984 the Maico 490 was being marketed as a 500 even though it remained a 490. Almost an entire decade later in 1992 the 490 would finally make the jump to 500cc. Merkel had the stroke increased from 83mm to 85mm upping the displacement from 488cc to 499cc. The Maico 490 was now and forever a true Maico 500. Rodem BV bought Maico in 1995 and the production moved to the Netherlands. The company name was changed to Maico Motorcycles N.V. where N.V. is "Naamloze Vennootschap" in Dutch. This nomenclature is commonly used by Dutch companies for "Limited Liability Company". However Lorenz Merkle kept and (as far as we know) still holds the rights to the Maico brand name.

In 1998 the big bore Maico received an upgrade in the form of a hydraulic clutch, but unfortunately things went south for Maico Motorcycles N.V.. The company was not able to secure funding and ownership soon reverted to Brouwer Motors BV which was the largest shareholder at the time.

When Brouwer Motors BV ceased its production, Axel Koestler brought Maico back to Germany at the turn of the millennium. Koestler's relationship with Maico dates back to the 1980s when they made their own gear sets for the early Maico 490s. Koestler continues to build and sell brand new Koestler-Maicos out of his shop in Leverkusen Germany producing around 50 bikes a year.

The latest innovations however are coming out of the UK with British made Maico International. The custom hand built British brand is heavily invested in Research & Design and in 2011 they have widened their focus from chassis improvements to engine design. Details are tight lipped at this time however Maico International has announced a new engine produced in collaboration with a lead engineering manufacturer for "F.1.". "We are succeeding in engineering some serious quality back into the bikes on all fronts with some very high end parts and manufacturing" says Vincent Page of Maico International.

Next year marks the 30th anniversary of the mighty Maico 490. Still being manufactured and improved upon for three decades by several companies it is one of the longest surviving dirt bike engines. The 2010 Maico engine uses the same piston as was used in 1981 and the same connecting rod since 1983. The similarities do not end there as there is a large matrix of parts which are shared across the various years. The largest change may be yet to come as we wait in anticipation for the details of Maico Internationals' "F.1." engine in 2011.

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