A while back, Jeff Mullins of Mullins Manufacturing (408-749-9856), a Maico specialty house, approached me to port, thermally coat and bore his personal Maico 440 cylinder. After a bit of deranged thought on my part and some talking to Jeff, I decided to install a reed valve setup on the cylinder. I consulted the AHRMA rulebook to ascertain the legality of such a move. The Sportsman class rules essentially say that whatever could be done then, can be done now. Nevertheless, just to be extra safe, I telephoned Jeff Smith and also Dick Mann. I was informed that as long as I did not use a modern reed cage assembly we would be legal. Dick Mann also asked me to keep in mind the sprit of the rules and I told him I would. While I did reed conversions “back in the day” in the 1970s, these were primarily done to piston-port 125s and 250s. The big Maico was going to be a whole new ball of wax.
From the first initial break-in ride, it became obvious we had accomplished these goals. Power output was increased dramatically across the board and the hit was gone. We went up one tooth on the countershaft sprocket and down three in the back. The engine started to settle down and stretch its legs. Jeff kept saying, “It’s awesome, awesome!” I just nodded and smiled. Building the “Replika Maschinen Inc. Big Reed Maico,” as most prototypes are, turned out to be a major project and nothing for the faint hearted. We first had to decide on a period reed cage that would be compatible with the cylinder. What at first appeared to be a shortcut turned out to be anything but. In the end, we designed both a six- and eight-pedal vintage reed housing, which we now manufacture. The housings are CNC machined aluminum billet; they must be welded onto the cylinder and will accept only period reed cages.
There are a number of steps involved in the process of properly turning a piston-port engine into a reed-ported one. A machine shop is necessary, including a lathe, vertical mill, band saw, oven and a TIG welder, to name just a few of the necessary machines involved. Quite a bit of cylinder porting is also involved; the cylinder must now match the upgraded intake system. I spent some 20-plus hours on the porting alone. After the RMI Big Reed Maico operation was complete and before we bored the cylinder to size for the piston, we “thermally coated” the cylinder, cylinder head and the piston. The cylinder and head were coated with a thermal dispersant to dissipate heat. The piston crown and the cylinder head combustion chamber were coated with a thermal barrier to help raise the combustion chamber temperature. The piston skirt was coated with a dry film lubricant. Additional information about thermal coatings can be accessed from our website, www.replikamaschinen.com. Careful assembly followed, along with a long and thorough break-in period. A colder range spark plug and jetting adjustments were well in order. Other adjustments and enhancements to the engine assembly are being worked out, tested and assimilated at this time. By the time you read this article, the RMI Big Reed Maico will be available as a kit. At the AHRMA Hollister Hills national, I spoke with the owner of a Maico specialty house. He looked at the engine and said, “That’s what the factory should have done a long, long time ago.” Don Redmon is the owner of Replika Maschinen Inc. (831-461-0806). [AHRMA Home] [News Flashes] [Events & Results] [WebMart] [Rulebook] [E-Mail Directory] |
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There was a reason
the “works” riders from Maico generally rode
the 400 instead of the 440, and that was smoothness of
power delivery. I wanted the same for the big boy. My
initial goals for the engine were a factory look, to
smooth out and broaden the torque band, improve throttle
response and of course give it more usable power. While
some may think us insane to want to add more power to any
big bore, my aim was to remove the violence and put the
power where needed with responsive delivery.
