Any other 2-stroke lovers??

[jkv357]

Originally Posted by old jupiter

JKV, I like your collection. One thing I have that might be of interest to someone like you is an old dusty box of engine parts for a Harley Davidson (Aermachi) RR250 2-stroke roadracer from the '70s.(SNIP)

Thanks.

Like the radial-finned heads? That's an interesting bike for sure - and one I would like to have.

Maybe just a bit out of my league though.

[old jupiter]

Oh no, you're thinking of the line of smallish and rather undistinguished air-cooled 4-stroke singles that HD acquired when they bought out Aermachi. No, the RR250 was a state-of-the-art early '70s Grand Prix roadracer, water-cooled, which took the world championship with Walter Villa up. These were the same years when Harley's Sportster-based flat-track bikes, developed by Dick O'Brian, were beating everybody including Kenny Robert's Yamaha. I'll see if I can find a link.

IIRC, some of the Aermachi people started Cagiva . . .

(EDIT) Maybe this will work. Engine exterior photo on row 5:

https://www.google.com/search?q=Harl...HVsjDsYQsAQIHg

[jkv357]

Originally Posted by old jupiter

Oh no, you're thinking of the line of smallish and rather undistinguished air-cooled 4-stroke singles that HD acquired when they bought out Aermachi. No, the RR250 was a state-of-the-art early '70s Grand Prix roadracer, water-cooled, which took the world championship with Walter Villa up. These were the same years when Harley's Sportster-based flat-track bikes, developed by Dick O'Brian, were beating everybody including Kenny Robert's Yamaha. I'll see if I can find a link.

IIRC, some of the Aermachi people started Cagiva . . .

(EDIT) Maybe this will work. Engine exterior photo on row 5:

https://www.google.com/search?q=Harl...HVsjDsYQsAQIHg

That's what I was thinking of, and why I said it was a bit out of my league.

I didn't think it was water-cooled though.

[old jupiter]

Oh, when I was talking about modern 2-strokes and emissions, I should have mentioned Ossa, an old name in (mostly) dirtbikes, who stunned the motocross and trials worlds by coming up with a new-tech fuel-injected two-stroke that wins races and meets current European emissions standards, this after 2-strokes had long been written off. And even cleaner and more efficient 2-stroke technology is on the way.

Again, Hal, I agree that such developments barely make a dent in the awful environmental mess we humans have got ourselves into; for that matter, none of the admirable do-it-yourself eco-modder project car ideas on this site make more than a slight dent in the overall problem. But at least they are better than not doing anything. Incremental improvement is what the Hundred Pound Rule of Motor Racing is about. It states: "There is no one place you can take a hundred pounds out of the car; but there might be a hundred places you can take out one pound." We desperately need some breakthroughs, as Bill Gates has been saying recently. But meanwhile we need to be "kaizen-ing" (Jap. term for continually refining existing products and technologies) what we already have.

[Grant-53]

There many ways to reduce our energy consumption and pollution. I am old enough to remember the 1973 gas rationing and the algae in Lake Erie. We were told the end the world would be 1975. Forty years later some things have actually improved. I am looking to restore a 1988 50cc Honda Elite scooter and streamline it. Target is 500 mpg at 30 mph.

[jkv357]

Originally Posted by Michael Moore

I won't address fuel economy, but I received today a 2015 KTM 250SX 2T single engine for a project. The engine less carb, exhaust and shift/kick levers weighs 46.5 lbf, but in standard MX trim puts out nearly 50 hp (significantly more than the 4T 250 MX engines).

Sounds like a good thing to me!

cheers,
Michael

Can't wait to see what you come up with Michael. You have done a bunch of really amazing projects over the years!


Jay

[cRiPpLe_rOoStEr]

Originally Posted by old jupiter

Rooster, what a cool car! Tell us more.

That's a Brazilian version of the DKW, made under license by Vemag. But that front-clip for the '67 model was unique for the local market, not used anywhere else. The engine is a 1.0L inline-3.

I am old enough to remember the 1973 gas rationing and the algae in Lake Erie.

Algae and other aquatic plants such as the Lemnoideae could be a good feedstock for biofuels.

[doug30293]

Originally Posted by old jupiter

Was surprised to find this old thread revived.

Despite this, the investigation found no significant pollution, no rainbow-colored oil flows anywhere around the lake. My guess when reading about this long ago was that the fuel/oil comprised such light fractions that it mostly evaporated into the air . . . hardly desirable either, but in any case no smoking gun was found (and I forget whether lake sediments were looked at).

First post here. Forgive me if I am barging in on this.

The older petroleum premix oils often left less oil film on the water because, as you suggested, they tended to leave the engine as vapor. Modern synthetics leave the engine essentially unchanged. The fact that they don't burn is one reason you can run them up around 100:1.

The synthetics used in modern outboards do leave a film on the water, in part because a 300HP bass boat motor sucks a lot of gas and therefore a lot of oil. I live on a large lake that was once popular on the bass pro tours. One Saturday we went swimming after a big tournament. The water had a noticeable film and so did we when we got out. After that I never went swimming after a holiday or tournament.

Oil injection such as the old Yamalube system was significantly more efficient than premix. I did some testing back in the 70's and found the Yamalube systems typically used oil at about 70:1 to 90:1 at a time when premix was limited to 40:1. The oil pump was connected to the throttle cable to increase oil with fuel consumption. I saw numerous bikes come into our shop with the lube cable disconnected (or broken). They never seized as long as oil was getting to the pump.

Doug

[cRiPpLe_rOoStEr]

Gotta love the good old Castor oil, at least it's biodegradable

[doug30293]

Originally Posted by cRiPpLe_rOoStEr

Gotta love the good old Castor oil, at least it's biodegradable

It also had a pleasant 'barbeque' smell. One of the early synthetics was glycol based. It made your eyes burn and was probably toxic as well. Though it was probably the best lubricating two stroke premix at the time it had absolutely no rust preventative properties whatsoever. Leave the bike over the winter and the engine was rusted solid by spring.

I think all synthetics are polyol esters now. Not as rust inhibiting as petroleum but certainly better than glycol.