By Tom White

Harley-Davidson’s first entree into motocross was a byproduct of the marriage of Harley, Aermacchi and AFM. When parent company AMF asked Harley to enter the growing motocross market, Harley-owned Aermacchi was a reliable source of two-stroke engines. At the 1974 Omaha 250 National, Sonny DeFeo debuted the first Harley-Davidson MX-250. Only 65 of these bikes would ever leave the Milwaukee factory. The 242cc Aermacchi-built engine was housed in a chromoly frame, built by Champion, and the whole package hit the scales at 212 pounds.

The MX-250 used Showa forks and Kayaba fork-style rear shocks. The front hub was from a Yamaha, while the rear wheel housed an Airheart disc brake powered by an H&H caliper. Other components included K&N handlebars, Oury grips, Magura controls, Sun rims and Buchanan spokes. The Aermacchi engine actually made good power when mated to a 36mm Mikuni carb—although some engines came from Italy with Dellorto carbs. The expansion chamber was silenced by a pickle-style muffler, both of which would break or fall off with regularity.

What was the bike like to ride? It wasn’t fast, but it had good low-to-mid that required short-shifting. Most test riders claimed that the fork-like rear suspension was surprisingly good, and that the Showa forks were very good. Some MX-250 racers took the rear disc brake off and mounted a Yamaha hub with a drum brake instead. There was no motocross success, but Bruce Ogilvie won the 1975 Baja 500 on an MX-250. Production was halted in 1975, but Harley would try again with a new bike in 1978. The new 1978 MX-250s were raced by Marty Tripes, Rich Eierstedt and Rex Staten. Harley’s motocross effort ended in 1979 and was never started up again.


Because the 1975 MX-250s were only available at select Harley dealers and nominally priced at $1375, the 65 examples of the MX-250 are very rare and very valuable to serious MX collectors. At the 2020 Mecum Motorcycle Auction in Las Vegas a 1975 MX-250 sold for $23,100.

This was the only Harley motocross bike to this point. There were no 125 or 500 versions. There was a second Harley-Davidson MX250 in 1978, but it was also a sales failure.

Parts for the engine can still be found from the supply of SX250 trailbike engines. What is unobtainable is the Champion frame with its square-tube swingarm and Kayaba (labeled as Red Wing by Harley) rear forks/shocks. The Showa forks, their cast triple clamps and the Hurst/Airheart rear disc brake are also scarce. It’s a huge bonus if the Preston Petty “Mudder” fenders are in good shape!

For more info go to the Early Years of Motocross Museum site at


36mm Mikuni carbAermacchiAirheart disc brakeBuchanan spokeschampion frames.classicironharley-davidsonkayaba forksmarty tripesOury gripsrich eierstedtsonny defeo