Two-stroke revival - Will TM keep them alive?

[Voutare]

Don't laugh! If Harley tries to get into MX we'll all be riding 900cc flatheads!

And that would be awesome. Seriously. Think about it. I'd kill to be able to take a 883 Sportster through the whoops.

[Phathry25]

And that would be awesome. Seriously. Think about it. I'd kill to be able to take a 883 Sportster through the whoops.

You've clearly never ridden one. I rode one ONCE at a practice day at Savannah, GA. That was enough to convince me to never ride one again.

[Wilmx829]

My dad used them when he raced flat track. That would be cool if they made an mx bike tho

[JETZcorp]

The idea of Harley-Davidson trying to get into motocross is just hilarious. That in mind, it would be a bit more hilarious if they hadn't done it in 1978. Oh yes, that's right, even Harley-bleeping-Davidson went with the two-stroke.
http://www.mxtracks.us/mx/phpCalifornia ... ocross.jpg

Before the two-stroke revolution, though, the traditional Hog wasn't far from the MX scene. The pioneers of off-road riding would typically be seen on gigantic V-Twins, complete with foot-clutch and H-Pattern shift.
http://www.youtube.com/watch?v=h-GO1yWJIAw

[jlv]

That's not a Harley. It's an Aermacchi with "Harley Davidson" written on the tank.

[JETZcorp]

Well, after a brief search, here's what I came up with for info on the Hawg 250MX.

The project started in the late 1970s, when Harley, under the control of leisure-products conglomerate AMF, decided to test the market with its first-ever motocrosser. As with its other lightweight machines of the era, the company looked to its Italian-based subsidiary, Aermacchi, to produce the bike.

The end result was a one-of-a-kind machine that, unfortunately, lasted just a year in the Harley lineup.

The MX250 sported an Italian-made 250cc two-stroke motor and steel frame. An international mix of components rounded out the package: Japanese Kayaba suspension, Spanish Akront rims, Japanese ignition and an Italian Dell’Orto carb.

By most accounts, it was the engine that shined in the MX250. According to magazine tests of the day, the MX250 motor was good for just over 32 horsepower, second only to the Can-Am 250. That should come as no surprise, since it had been developed on the racetrack with a factory team that included Rex Staten and Marty Tripes.

That power required caution, though, since it came on explosively, a trait that wasn’t helped by the stiff stock rear suspension. Also hurting the overall handling was the bike’s weight, which, at 250 pounds, was about 25 pounds heavier than the competition.

Still, the magazines of the time agreed that the MX250 was a great first effort that merely needed some refining.

That’s consistent with what the owner of this restored MX250, now on display in the Motorcycle Hall of Fame Museum at AMA headquarters in Pickerington, Ohio, discovered when he took the machine apart.

“It’s a nice little bike,” says Jeff Willis of South Point, Ohio. “But there were a lot of things that even I could have done to make it lighter. Probably if someone had spent another year or two developing it, it could have really turned into something.”

Unfortunately, that never happened. Although Staten managed to put a Harley on the podium of an AMA motocross National in ’77, the factory team was disbanded for ’78, and the production model lasted just one year in the company’s lineup.

Then it was gone. And so was Harley’s involvement in motocross racing.

http://www.motorcyclemuseum.org/classics/bike.asp?id=76

I have to say, I expected it to be heavier than a typical 250, but that weight is just downright shameful. That's the kind of weight that would put it on the heavy side for the 500cc class, let alone 250. In 1982, Wheelsmith Motorcycles (renowned Maico expert shop) had their 490s down to 234lbs, and Open works bikes were down to 225 that year. I don't know were you could even find the weight to make a 250 that heavy. Did they use lead instead of foam for the seat?

[Wilmx829]

that harley looks alot like a motor i have around here.
One of my freinds gave me a klx250 with no motor. i stuck a 1979 pe175 stroke in it and its acutally fun to ride in the woods.

[JETZcorp]

The motor is pretty generic. Looks quite a lot like the Rotax-powered bikes like Can-Am or KTM. Though, I think Can-Am ran rotary valve instead of reeds, which is pretty hardcore. Come to think of it, that Harley doesn't look like it's running reeds at all; it uses the piston for that, too! They say the reed valves give the engine better low-end power, and on the 125 and 250 bikes that's generally true, but there were exceptions. Well, one exception.

Yay, a JETZ history lesson!

By the mid-70s the reed valve had pretty much become standard over the piston-port in bikes, including most Japanese bikes and Huskies. Maico decided to stick with piston port though, probably because of money constraints but reliability was probably also a concern. With the '81 490, they had more low-end power than any other bike in its class, and to this day the only 500s to have such a usable powerband have had Maico written on the sides. A lot of guys make the mistake of adding reeds to the 490, and all they manage to do is slow the throttle response and add the danger of sucking a reed. They finally started using the reed valve on the 490 in 1983 (ten years after Yamaha) and created a brand new engine that year which brought tears to the eyes of those who tested it. Then in April of that year, they went bankrupt and have been clutching at straws ever since.

They started using reeds on the 250 starting in '81, and although it makes the throttle response a little slower, it's considered by some to be the best dual-shock 250 ever made. My dad has one, and it keeps up with a Husky 430 from the same year, give or take depending on how twisty the road is.