Any other 2-stroke lovers??

[radioranger]

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

[radioranger]

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,

[cRiPpLe_rOoStEr]

How should we be supposed to not love this?

Even though the Brazilian-designed front clip harmed the fluidity of its original design, it's still a beauty.

[jkv357]

Here's my Derbi GPR when I got it -



After a few mods -



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



More recently -



As it sits currently -



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

[Hal]

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.

[cRiPpLe_rOoStEr]

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.

[Hal]

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.

[cRiPpLe_rOoStEr]

Originally Posted by Hal

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.

[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

[old jupiter]

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.