Any other 2-stroke lovers??
 

Raced outboard hydros many decades ago, have always liked 2-strokes for their simplicity while recognizing their drawbacks (although is it really a drawback to be able to pull in front of some snotty tree-hugger in his Prius and bury him in the deadly blue cloud??!!).

I currently have a '76 Yamaha RD400C 2-stroke streetbike, one of the early good-handling quick middleweights of the kind that led to the coinage of the term, "crotch-rocket". But I can't justify having two bikes around, with all of the other junk, so I might be selling it to get something lighter in weight that I can load in the back of my work truck for chasing parts when the truck is on the job. It will be another 2-stroke, a '75-'76 Yamaha RD125 twin. I'll fabricate my own pipes for it, and do some mods to improve handling and make it look cooler.

So far I haven't related this to fuel efficiency, which is not generally one of the shining attributes of 2-strokes. Since this is a little bike with a little engine, the mpg numbers will be good compared to most cars, of course, and there are a couple of small tricks I'll do to improve them. But I expect that among this gathering of brainy gear-heads we do have some dedicated "'strokers" here. If so, has any of you heard of a company called Envirotech? They have engineered some sort of retrofit fuel injection system that they claim to have sold widely in the 4th World to owners of smoking 2-stroke scooters and tricycle-cabs and such. Have any of you managed to acquire one (the company won't sell them here), or know anything about this?

Yup - I love 2-strokes. First street bike was a RD400 back in '79. Also owned a RZ350 for a while.

My RD was almost identical (same paint, same cut-down seat, expansion chambers, but mine had Clubman bars) to this one I found on the web -

http://i132.photobucket.com/albums/q...g/5e027cc4.jpg.

I had numerous 2-stroke dirt bikes as well.

Right now my oldest son is trying to talk me into a CR125 instead of the XR100 he's riding now.

One of my riding buddies had a Suzuki GT550/3 cyl with chambers that sounded amazing. I used to follow him just to listen to it. I loved the smell too...


Jay

I still have my old 75 RD350 and 83 RZ350, they were purchased new by me. They sat from 1984 (when I retired from roadracing) until last fall when I drug them out of my shed and disassembled them. My RZ is running at present and my RD still needs a few weeks of work.

My wife has two smokers as well. She has a Honda elite 50 with an 87cc stroker and a Yamaha Zuma 50 with a 70 big bore. Once in a while she will get a comment that her bike is smoking....

She is also planning on riding the RD.

http://veloliner.com/rd350/rdandfriends.JPG
Ah the good old days.

2 Stroke Lover!

I love that band.

+1 on the 2-strokes! There is nothing like a 2-stroke when it hits the pipe. Not that I own one anymore....
I did fix an RD350 for my neighbour. What a blast! Basically, way too much power for the chassis.

A stock RD will only get around 40-45 mpg.

The number one upgrade for these engines is digital ignition. The later RD400s had CDI which basically eliminated spark plug fouling issues. With a stock RD, you basically have to take a handful of spark plugs along at all times. There was a company that made a timing advance setup for these as well, which basically doubled fuel mileage around town. I would seriously look into that, because I believe there was no timing advance on these motors. I think it even had a TPS for timing inputs.

Good luck!

Mechman I would like to comment. Actually you want an ignition retard as the engine comes on the pipe. Sort of the vacuum advance mechanism that was common in automobiles of the time. Light load advance... heavy load, start retarding. My RD is going to stay with the points. It has made it 37 years with them.

As far as having too much power for the chassis, remember the TZ350, about twice the power and in a chassis that was 50% lighter and still manageable. When compared to models 6-8 years newer (The RDLC and then RZ) it is bouncy, twitchy but without that comparison it was state of the art.

When I rode my RD on the road. It got 40 mpg but I could get 50 on the road. About 12-15 mpg at the track.

I do believe that time has passed the 2 stroke engine. At least as I know them. Using the crankcase to scavenge the engine, carrying oil and unburned fuel with it is just not politically correct. If you want one better find it and rebuild it. Almost all the parts are still available. My RD is going to stay the same as when I raced it. Stock pipes, rear sets.

My bikes are now antique or historic vehicles and will probably be ridden less than 1000 miles a year. I haven't ridden the RD since back then but rode my RZ a couple of weeks ago. It hits the pipe at about 6500 and lasts to 9500. The variable exhaust port really fattens the power band. It still is very old school when compared to what more modern performance two strokes can do. But it is pretty light weight and with the short wheelbase it makes it fun. Seems like every time that I have gotten it out is was just after a rain and the clay on top of the gravel makes it just want to slew.

i heard about a company retrofitting those 2t paddicabs in India witha propane kit. You would need an oil injection engine though.

I am newly in posession of a Puch mk-II moped. It was my mother-in-laws fathers, but she is letting me boot about on it for the summer.

I love the smell of 2-stroke in the morning.

http://i422.photobucket.com/albums/p...n/GOPR0454.jpg

Guilty :thumbup:

Excellant! I didn't suppose this site was populated entirely by bark-eaters and CARB bureaucrats, but I'm glad to find you contrarian types!

It certainly is possible to manufacture more fuel-efficient and "clean" 2-strokes with port fuel injection, pressure oiling, computerized ignition getting feedback from various sensors, closer manufacturing tolerances, ceramic-top pistons, and so on.

It isn't likely to happen very often, however, because the Green crowd has cowed the manufacturers and brainwashed politicians by castigating all 2-stroke engines as "filthy" in testimony before Congress and elsewhere. Why this crowd is consulted for this sort of "technical expertise" is a mystery. By and large the Greens were liberal arts majors, have had their noses in books most of their lives, and have never had grease under their nails. They imagine that products on store shelves came to be there by some form of immaculate conception, and have no clue as to what engineers and blue collar skilled tradesmen actually do, and they share this ignorance with our educational, political, and legal establishments. So when they denounce 2-strokes as "filthy," the powers-that-be readily accept it, having no frame of reference by which to judge such "technical" assertions.

Yet even conventional crankcase-oiled 2-strokes like my RD are a whole lot cleaner than the old 2-strokes that made the reputation that stuck. Up to the late '50s, 2-strokes generally used about 16:1 pre-mix ratios, using oil we might now refer to as "bunker C". And since most owners of 2-stroke equipment were as clueless then as now, they would pick up their chainsaw, still half-full of stinky four-month-old fuel, and try to fire it up without vigorously shaking the saw to re-mix the oil that had all settled out of the gas. When the engine finally started, the oil still had only partially re-mixed from all of the shaking of the extended starting proceedure, and the oil-rich mixture would pour out clouds of smoke. Later on, of course, the engine would go oil-lean and maybe stick, which added the the 2-strokes undeserved reputation for reliability. To this day, hardly any homeowner knows the few easy tricks to keeping his weedeater and backpack blower and chainsaw and similar equipment happy, so the "unreliable 2-stroke" nonsense continues. Even guys who should know better . . . decades ago I'd go for a weekend of dirt riding, and when I got out of my tent Sunday morning, I'd go over to my bike and tip it back and forth a bunch of times, with other guys scratching their heads. Of course, that oil was SUPPOSED to stay mixed, but why take a chance?

Anyway, since the old days we have gotten oil that works at 50:1, 80:1, and even thinner, and some of it really does stay mixed pretty well. Result: a lot less smoke. Since the mid-'60s, outboard motors no longer drain excess gas/oil out of the bottom of the crankcase while trolling, but send it back to the carburetor (this change meant that the new motors wouldnt troll as smooth as the old ones, but that was a price worth paying). Unfortunately, the politicians, brainwashed by the Greens, are banning 2-stroke outboards from lakes all over the country. Funny, Kiekhaefer, maker of Mercury outboards since the Forties, had their own private "Lake X" in Florida where they tested engines. In the late Sixties, after they had run hundreds of thousands of gallons of (the old style) pre-mix through hundreds of engines (mostly lacking the crankcase re-cycle circuit) on that small lake, somebody thought to get a lab to test for oil pollution. Next to none was detected; the fractions were light enough to have evaporated. Banning 2-strokes to "save" lakes is like most of what the Green-influenced politicians come up with: High image, low content.

(This wasn't intended as a political editorial except as related to 2-strokes. But lest someone mmisunderstand, please accept a one-paragraph digression because I don't want you to think I scorn all environmentalists. Some are very sharp, have far more tech expertise than I do, and insist on practical results over feel-good band-aid fixes, and they are gradually moving their movement, kicking and screaming, toward a more productive and cooperative attitude. The knee-jerk Green-bashers and deniers on the other side need to be re-programmed in a similar way. And government at all levels needs to wise up (making bio-fuel from corn instead of the many alternatives is a particular example of poorly executing a basically good idea). End digression and beg pardon.)

I'm interested in hearing more about the variable timing system retrofit. My RD400 has what could be called the "First generation" ignition upgrade: a pair of K-Mart coils, and the points-cam reground mostly by hand for more dwell, oh and the plugs gapped to .032-.035". This was a popular fix in the mid-'70s, and gave a real improvement in ignition and plug life, though not as good as the later electronic ignitions, I understand.

Well I had lots of two strokes GT380's one with chambers, and even a GT750 water buffalo and they never got even near the Mileage of my GS1000, i think I got over 50 mpg at 70 MPH and interestingly enough though the oil costs more because a four stroke , or most of them have no seperate gearbox, so if you ride hard you better change the oil a lot, like 2000 miles or less, and a two stroke running golden spectro uses only about a pint per 3 or 4 hundred miles if you lean them out , which you can do with the Spectro so your oil costs are actually higher with a four stroke , or very close, My GT 380 stock went from 100 top end to almost 110 with the spectro after a few hundred miles , Yamahas were tuned to go fast never very happy running slow like a Suzi.

Another quick note on two stroke oil, lots of them are completely bio degradable rated now, even though all oil is ,

not to sound like an advertisement here but the spectro is amazing, I accidentally put too little oil in my 6 hp Johnson outboard and it seized up , after flushing th ecylinder with WD 40 and adding oil it ran again, I added the spectro premix race oil to the gas next time and honestly it ran a good bit faster than when new !!

i have a really crude design, Jawa 350. Has a consumption around 50MPG. I rode the old version (jawa modell 634) for about 20000kms and it was usually around 45mpg. (older carb and point ingnition (very poor design, needed check and setting every 600kms))

the point about the oil cost is a good one. never thought of it this way. :D My GS 450 needs an oil change every year. 2.5-3 liter of 10w40 bike oil. The Jawa requires very simple 80w90 transmission oil, 1 liter. there is a difference...

But i have to tell, if it's about ecodriving, the Jawa would not be my choice. I'd go for some 125 4 stroker for the everyday communting. But since I do not want to buy a new bike, I use the Jawa anyway. :D

would love to push the consumption lower though... but do i drive it enough for investing a lot? :D

Back in the 60's and 70's I had a couple small-displacement, single-cylinder 2-stroke scramblers. Great little bikes that hauled my skinny carcass all over the PNW. In the 70's I had a '66 Saab Monte Carlo 850, a 3-cylinder 2-stroke car that was quite a change of pace from my prior '53 Plymouth sedan with a straight-six flathead.

I'm currently planning a motorized bicycle, but have pretty much decided to go with a 4-stroke. I want it to be really quiet, and that seems incompatible with a 2-stroke.

I know this is a motorcycle area. But if you can talk about two strokes in an economy sense, then I can talk about my Banshee. I have had a lot of ATVs since letting her go, but she is the only one I miss. Getting on the pipe and your arms stretch out, and that smell. I still run my weed wacker on expensive oil so I can enjoy that stink. I use to love going out on the gravel and lugging in too high a gear. Bury the throttle and in just a few seconds you were in the power band and throwing rocks.

There is an engine modification that is a win-win-win proposition in almost every possibly way except the ease of doing it, . . . and like nearly any other engine work, it is a lot easier to do on a 2-stroke. Establishing a good tight squish-height gives an engine better swirl, slightly more compression with probably less tendency to detonation, more torque, AND better fuel efficiency, ta-dah!, and a great feeling of pride on the part of the fellow who does it, not least because he feels himself part of the somewhat limited in-crowd who knows about the technique.

I'm guessing nearly everybody here has at least heard about squish (Brit. "quench"). Any amateur mechanic rightly should know, since the technique dates back nearly a hundred years to Sir Harry Ricardo (who also pioneered water injection). Setting the squish on a car engine has to wait for when you're doing an engine overhaul, since it involves machining the deck surface of the block. But on an old 2-stroke bike it's not a huge deal to pull the jugs and deck them, and with certain engines you can set squish by shaving the head(s), and leave the cylinder(s) alone!

You can also make a 2-stroke (or whatever) a bit more fuel-efficient with piston coatings and with exhaust system thermal wraps, and a few other tricks.

This is mere supposition, but I believe that after I overhaul and upgrade (for fuel efficiency and longevity) my politically-incorrect 35-year-old RD400 2-stroke, its total environmental impact over, say 100,000 miles (yes, it's do-able), including fuel consumption and emissions, will be less, far less, than the total environmental effect of a brand new Prius being manufactured, shipped across an ocean, and driven 100,000 miles here.

I comfort myself with this thinking every time I overhaul (and improve for fuel efficiency) any old car or truck (admittedly I choose them for their fuel efficiency potential, which wasn't the case with the RD400).

(Uh . . . I have to admit that MY RD400 would do better in this comparison with a Prius than would anyone else's RD400 . . . because I'm getting too old to ride an RD like it's supposed to be ridden).:eek:

"If it don't smoke...
...must be broke"

2 smoker here!

Working on my 1974 Suzuki TS 185 to get her on the road then we go for MPG, of course just trying to improve the breed, knowing it will be tough, but totally dedicated to smokers!

Great thread...

Here was my RD350's first breath in 30 years.
RD350 short ride

I'm also favorable to the 2-strokes.

workaround ideas to discuss among friends: Two-stroke engines: still a viable technology?

Had great luck with the golden spectro sythetic two stroke oil very good results my GT 380 picked up 10 mph top end, dont remember the fe though was back in 76

with the spectro you can lean the oil mix quite a bit, saves oil use, I use it in my 4 hp outboard evinrude outboard and it runs smooth as a kitten, much slicker than regular injection oil

just had a thought the ts 185 uses gear oil in the tranny ,call up summit racing they can hook you up with some red line synthetic gear lube, they have pretty good tech guys there or call red line directly, got to be good for a half a horsepower. gee now I'm going bike shopping , I had many bikes the best FE was from a little S 65 Honda, one day ran out of gas riding with friends , a buddy found a beer bottle on the side of the road and drained off some fuel for me, ran at least 20 miles on it, 73 was a great year,

How should we be supposed to not love this?
http://automovelbrasil.com/assets/i/...68b0a602b5.jpg
Even though the Brazilian-designed front clip harmed the fluidity of its original design, it's still a beauty.
http://automovelbrasil.com/assets/i/...e8fb66c76a.jpg
http://automovelbrasil.com/assets/i/...a7c7a315dd.jpg

Here's my Derbi GPR when I got it -

http://i132.photobucket.com/albums/q...ps1vfeo6ns.jpg

After a few mods -

http://i132.photobucket.com/albums/q...pssdc3v0uw.jpg

Hangin' out with another Spanish 2-stroke, owned by a buddy of mine, at a bike gathering -

http://i132.photobucket.com/albums/q...ps1yjynq6d.jpg

More recently -

http://i132.photobucket.com/albums/q...psv3obgrbg.jpg

As it sits currently -

http://i132.photobucket.com/albums/q...psqaiz0pfp.jpg

Getting blue wheels and new tires plus a few details here and there.

Two Stroke fuel efficiency
 

Without some pretty major modifications you are going to be hard pressed to make any significant improvements in fuel efficiency with a two-stroke engine. The problems is that the for part of the cycle the intake and exhaust ports are open at the same time and a portion of the incoming fuel/air mixture goes right out the exhaust port. Expansion chambers work to increase power by using a reflected pressure wave to reduce the amount of charge that escapes into the exhaust port, but they are tuned to specific RPM ranges which reduces their effectiveness in daily riding situations. Some manufacturers attempted to address this problem by using things like sleeves and other valving arrangements on the exhaust port. By the time you do that you have increased the weight and complexity and lost some of the advantages of two-stroke design. The other problem, of "dirty" exhaust is that of having the lubrication for the cylinder and crankshaft being burned along with the fuel.
A solution to both problems would keep the incoming charge out of the crankcase altogether and using direct injection of fuel, hence my comment about "major modifications". It would require some sort of blower for scavenging air and a high pressure injection system, as well as replacement or modification of the cylinder so that the incoming air goes directly into the cylinder, and a way of lubrication the rod and crankshaft bearings. There seems to be a few companies that are working on this or producing kits, and there are snowmobile and jetski engines that are direct-injection two strokes that could be modified/adapted to a motorcycle frame.

From a 3rd-world perspective, I don't consider so bad to burn the lube oil. At least there would be no need to handle waste motor oils, that in my country are still often discarded incorrectly.

Given the air quality in the average third world country, maybe it would be better to push toward NOT burning the oil and find some incentives to reuse or recycle it.

It depends on other factors, such as the oil specifications and the proportion it's blended with the gasoline (or the ethanol). We must also consider that at least one renewable source of lube oil for 2-stroke engines is already known and relatively widespread (Castor oil) while for 4-stroke engines a similar development is going slow. A direct-injection 2-stroke running on ethanol (or CNG) using Castor oil is likely to have a lower overall footprint compared to a 4-stroke using regular petroleum-based lube oils.

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

Was surprised to find this old thread revived.

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.

Rooster, what a cool car! Tell us more.

Hal, it's a shame our species is so dumb as to have over-produced our numbers by, at this point, a factor of ten or twenty. Otherwise we could have all of the fun old high-pollution stuff (steam locomotives, anyone?) and not hurt anything much.

Even today's conventional two-strokes are already a lot cleaner than they were in the '40s and '50s when the oil was "bunker C" at 12:1. Even then there was some question of how bad they really were. Kiekhaefer Corp. (Mercury outboards) did nearly all of their testing including long endurance tests on a small body of water, "Lake X," that they wholly owned down in Florida. When the early environmentalists of that time (1963, maybe) got the state to question Kiekhaefer, the company had an outside lab come in and sample the lake outflows. Tens of thousands of gallons of gas/oil premix (and this was the old oil, not the more recent 50/80/100:1 oils we got later) had by that point already been run through hundreds of 2-stroke outboards over several years. Furthermore, outboards at that time all had a little bleed hole in the lower crankshaft seal to drain excess oil that could build up in the crankcase at trolling speeds (a few years later this crude feature was replaced by a recirculator line that ran the excess oil back into the engine behind the carb).
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).

And again, those were early 2-strokes. 2-strokes got a LOT better (or less bad) in the mid-'60s and early-'70s. And they are now a lot better yet, with the new direct-injection Evinrudes, which others are striving to emulate. And soon, so far as can be seen from a very promising project that is currently undercover while patents are being applied for, there will come a variety of "radical" 2-stroke that is a great deal cleaner yet, as well as more fuel-efficient. So the environmentally-incorrect ring-dings of our grandfathers' day have less and less to do with current technology as the years and decades go by.

. . . which is fortunate, given the awful destruction we have already visited on the natural world.

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.

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.

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.

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.

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


Jay

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.


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

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

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

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.