Metrakit 70cc Cylinder Kit

Will cooler heads prevail?

Sep. 29, 2007 By George Szappanos
In the world of mini quad racing, advances and technology seem to be growing by leaps and bounds. Less than a decade ago the industry was all but dead. Not long after the Chinese reintroduced the concept of an ATV specifically designed for youth riders, the aftermarket was busy working on go-fast parts to coax serious performance from these relatively docile machines. Although more than a few folks in the states have carved out nice little businesses building and selling suspensions parts, exhaust pipes, and ported cylinders, several not-so-small corporations have been hard at it for quite a bit longer. The names of European companies such as Airsal and Malossi have routinely been on the tongues of most anyone involved in mini-quad racing.  But for those desperate to separate themselves from the pack, the search for something even better never ends. Some have resorted to having their cylinder's ports reworked in an effort to extract even more power from them, and yet others explored further the high-tech scooter racing offerings from over the pond.

One such offering is from the Spanish company Metrakit. One of the first companies to introduce water-cooling to the mini-quad scene, their cylinder kit had a limited market since the vast majority of machines a year ago were still air cooled and lacked the ancillary hardware such as radiator and water pump that are required to run a liquid cooled engine. The tide is slowly turning and more and more new youth quads are being produced as liquid cooled. The market is finally ripe for a high end, performance liquid cooled cylinder. Or is it???...

metrakit install 002.jpg (76961 bytes)
The test machine was an air cooled  Kasea that required special fabrication to allow fitment of radiator.

The question becomes - why bother with liquid cooling anyways? Sure, all the 65cc motocross mini-cycles are LC'ed. And there's no denying they make serious power. But what about the water pump drag, and the extra weight of the coolant and radiator? Conventional wisdom would say that water cooling is only necessary if your engine is producing so much power that air cooling by itself can no longer dissipate the attendant heat produced by combustion, and engine performance and durability begin to suffer. Further, liquid cooling, by itself, should not translate directly to a power improvement. Does the MK cylinder really make that much more power? Only one way to find out - a Metrakit cylinder kit was purchased from

A few days later a fancy little wooden box appeared at our doorstep with our MK cylinder in it. The kit included a single-ring piston and hardware, as well as a three-piece cylinder kit. Also include were a variety of base gaskets so as to allow fine tuning of the squish. We were urged at the time of purchase to also include the MK Pro Pipe, since the combination was designed together and certain to provide best performance when used in conjunction with each other.

Modifications to the pipe involved cutting and welding the rear section of the pipe as well as fabrication of a custom silencer hanger.

Initial inspection of the cylinder revealed some unorthodox port values, at least for this writer. First off, at BDC both transfer and exhaust ports extended significantly below the piston top, as if the piston was not fully at the bottom of its stroke. Second, although the exhaust port seemed fairly large, the transfers opened later and were actually smaller than a stock cast-iron 70cc port. Very odd, but sometimes that's what it takes to make a significant performance difference. The cylinder was installed with the squish set to the requisite 0.8-0.9 mm of clearance and top end was buttoned up. To install the pipe, a bit of modification (cutting and welding) was required to get the rear portion of the pipe to fit under the grab bar. Although the pipe is designed for "mini-quads" in general, it seems the Kasea must be the oddball.

wpe9.gif (14134 bytes)
Chassis dyno testing revealed some very impressive numbers. Double the rear wheel power at 35mph!

Our chassis dyno evaluation consisted of a few variations. First, a baseline would be run with our existing configuration which included the Malossi aluminum cylinder and a very popular aftermarket pipe. (This test was performed at a previous time.) Next, the MK cylinder would be run with existing pipe (popular aftermarket) so as to provide a comparison of cylinders only. Last, the MK pipe was installed and run in combination with MK cylinder. Although no jetting or ignition timing changes were made between tests, clutching was modified to optimize each configuration.

The dyno charts clearly demonstrate not only the sizeable power improvement that the MK combo provides, but achieving that level of performance cannot be done with cylinder only. The port timing numbers would indicate that this cylinder wants to rev, and sure enough the MK combo returned best performance when clutched to run at 11-12,000 rpm. A pipe such as the MK Pro Pipe that tunes at revs higher than 11000 rpm is what's required to really make this setup work.

DSC03294.JPG (219326 bytes)
The Metrakit cylinder had few wondering about its potential, easily taking holeshot after holeshot.

Of course, seeing how the machine performs on the track is the real test. As they say, the "proof is on the podium". At its debut race at Round 4 of the ATVA Nationals in GA, our Metrakit powered Kasea easily holeshotted both motos and only a last turn highside crash denied us of a 1st place finish.

For sure, this kit was the real deal. With nearly a perfect holeshot record throughout the season and several convincing finishes, word has gotten out that this cool head has prevailed - by the end of the season, no less than 4 out of 5 of the top finishing machines were running this kit. For more information, contact Newsletter
Join our Weekly Newsletter to get the latest off-road news, reviews, events, and alerts!