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Mike Lecka’s Harley-Davidson

Story and photos by Pat Panzera, EAA 555743, ppanzera@eaa.org


During a visit to Sun ’n Fun, I found an interesting “aero conversion” in the engine workshop area. Mike Lecka had a stock 2004 88B Harley-Davidson engine on display, which he has adapted for aviation use. Mike is tailoring this engine for use in a single seat sport/racing airplane of his own design. The new aircraft is a single-place, low-wing, all-metal pusher that resembles a BD-5 at first glance, with a fixed main gear and a manually retractable nose gear. Although the cockpit area is monocoque, the firewall aft is of tube construction. This project was inspired by an article on Pushy Galore, written by Gary Hunter, in CONTACT! Magazine. Pushy Galore also graced the pages of EAA Sport Aviation in the June 1996 issue.

Artwork by Jim Ewing, as it appeared in CONTACT! Magazine.

Mike’s monocoque cockpit resembles a BD-5.

Mike is not a commercial vendor. His desire to display his engine at Sun ’n Fun was purely for fun. Mike’s engine (displayed in the automobile conversion engine forum area) attracted a lot of interest. When I asked him what type of aircraft builder seemed the most interested, he told me Pietenpol folks were asking the most questions. “A lot of people expressed interest in the Harley-Davidson engine, wishing it were a tractor design,” Mike told me. When I asked the designer how he might adapt the engine for a tractor installation, he said that he would probably do it the same basic way he has it now, shaft and all, but simply shorten everything up.

Although I couldn’t find the specifications for the engine alone (all specs I could find were measured at the rear wheel of the motorcycle for which this engine is intended), Mike contends that the 88-cubic-inch engine produces approximately 75 hp at 3800 rpm at the crank. There are optional heads available, which change the torque curve. Mike is opting to get heads that make the most torque at the lowest rpm for the engine that will actually go in his plane.


Mike is fond of the HD engine over other bike engines, since in its bone-stock trim there is nothing directly connected to the crankcase, such as a transmission. Not many motorcycle engines are built this way; most bike engines have the transmission as part of the case. Additionally, there’s no machine work to be done to the case to adapt it for aviation use. The built-in alternator holds the starter ring gear. “You bolt the ring gear to the alternator flywheel, hang your starter, and you are basically done except for the driveshaft,” Mike said.

Wright Flyer
Harley-Davidson powered Wright Flyer. Photo courtesy USU.

It seems that Mike is not the only one interested in the HD engine. The University of Utah shares Mike’s enthusiasm of this engine for use in an aircraft. Just before Sun ’n Fun ’03, USU successfully flew an all-composite Wright Flyer replica, powered by this very engine, which is a good five times more powerful than the Wright’s original 12-hp engine.

Wright Flyer engine
It’s hard to see from this photo, but the Wright Flyer engine is tucked under the leading edge of the bottom wing, between the seats. Photo courtesy USU.

USU even saw fit to use a stock Harley fuel tank to supply gasoline to the engine that powered the plane. “It exceeded all our expectations,” said Dave Widauf, the USU engineer who led the project. “We surpassed the Wright brothers by many, many feet.” Read more about the plane and its flights on this website: http://WrightFlyer.USURF.USU.edu. The Harley-Davidson engine was appropriate for the Wright Flyer replica, since, like the famous airplane, Harley was celebrating its centennial as well.

The 88B features twin counter-rotating balancers to fully cancel primary engine vibration. The balancers, tightly packaged within the engine, dramatically reduce vibration, making it an option for some experimental aircraft.

One stock Harley system that Mike is not pleased with is the ignition system. From what he understands, the stock ignition is designed to help the rear cylinder run cooler than the front cylinder, as its cooling air is somewhat blocked by the front cylinder. In an aircraft, the engine would be rotated 90 degrees so both cylinders face the oncoming air like a radial engine would.

Wright Flyer engine

With this de-tuning of the rear cylinder, some power is left on the table. Although the engine currently on the test stand uses the stock ignition, Mike’s solution is to go with an aftermarket ignition system, developed and marketed by Jeff Rose of ElectroAir, located in Waterford, Michigan. In addition to a better ignition system, Mike tells me that Jeff has a spark plug wire system that allows the use of two independent ignition systems to fire one spark plug. Although this is not a true “dual ignition,” it gets Mike closer to one than a stock system would. We’ll follow Mike’s progress and report on the ignition system in the future.


The 88B crate engine’s price is $3,495, and is available from your local Harley dealer. “If you do buy an engine from the dealer,” Make said, “it’s considered a replacement part, so there’s no warranty. This didn’t really bother me at that price. I wanted to keep the engine on the test stand for people to see every year at SNF, plus I want to be able to fly my plane with a Harley-Davidson engine, so I plan on buying another engine.” Mike added, “I’d rather buy new, as I really don’t like taking them apart. I rode Harleys for 12 years. I bought new ones off of the show room floor, and when the engine gets tired, I order a new one. Simply pull it out of the box and put it on the bike. I’ve never done anything to them, except maybe improve the carburetion and exhaust. I think they last longer, they give you less trouble, and when you start taking that factory engine apart, you’re just asking for trouble, in my opinion.”



88 cubic inches (1,450 cc)

Bore and stroke

3.75 x 4.0 inches (95.25 x 101.6 mm)

Compression ratio



85 ft-lbs at 3000 rpm


48.5 at the tire*


Pushrod-type overhead valves with hydraulic self-adjusting lifters; two valves per cylinder

Fuel system

Carburetion (40 mm constant velocity with enrichener and accelerator pump); electronic sequential port fuel injection (single runner, 45 mm throttle) bore

Air cleaner/filter

Elliptical-style chrome with spun aluminum insert; high-efficiency, pleated paper filtration


Single-fire, non-waste, map-controlled spark ignition system; electronic breakerless with multiple advance curve matrix


Dry-sump, internally mounted, crank-driven gearotor pressure and dual scavenge pump with spin-on 10µ pressurized oil filter



*See comments in my editorial.

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