small diesel engine moped.
- Thread starter industrialphreak
- Start date
The Germans made one in the 50's that worked on diesel, gas ( regular and white) kerosene and paraffin, that was under 2 hp
Necromancy FTW!
Hi everyone! My name is Dmitry, I live in Germany and currently experiment with ethanol fuel in my lil 4stroke scoot.
Sorry to resurrect an age-old topic, with my first post no less - but since I have stumbled upon it, I'd just thought I'd register to show you something... This.
Some guy in Ukraine thought he'd take RC compression engine tech and scale it up a notch.
To do so, he took off the cylinder head off his 50 ccm Honda 2stroke, enlarged and re-threaded the spark plug hole (well, maybe he did that in order to use bigger automotive plugs in the first place - but who cares), made a screw-in muff for a counter-piston to go in place of spark plug, adapted a bolt to screw into said muff as the counter-piston. Prolly shaved the cyl head as well IOT reach appropriate compression, as well - he doesn't tell.
Max CR with counter-piston screwed in completely is calcultimated to be around 21:1.
Fuel is 3/4 pump diesel, 1/4 gasoline; no info on 2 stroke oil (1:50 as per standard, I'd wager).
Engine governing is with carb and throttle plus adjustment of CR with the counter-piston.
10000 km claimed clocked.
No info on MPG (might be a bit lower than possible since he says he's overjetting the carb for cooling purposes).
Crankshaft and bearings are taken from a 70 ccm model so they can take the beating from such a high CR, but this may or may not be a necessity for you -depending on whether the low-end of your particular engine can take bigger bore cylinders than what you have installed. Many 50ccm 4stroke Chinese scooters are known to be upgradeable to 100 ccm(keeping same CR) without crankshaft upgrade, so look up whether your 2strokes also can. Or you down-grade from a bigger bore to something your engine's crank can handle.
Myself, I have a 4stroke only, which precludes me from conducting such experiments, with a pretty packed cyl head and whatnot, but I may buy myself a 2stroke engine sometime in future just to test it myself.
Have a day
Hi everyone! My name is Dmitry, I live in Germany and currently experiment with ethanol fuel in my lil 4stroke scoot.
Sorry to resurrect an age-old topic, with my first post no less - but since I have stumbled upon it, I'd just thought I'd register to show you something... This.
Some guy in Ukraine thought he'd take RC compression engine tech and scale it up a notch.
To do so, he took off the cylinder head off his 50 ccm Honda 2stroke, enlarged and re-threaded the spark plug hole (well, maybe he did that in order to use bigger automotive plugs in the first place - but who cares), made a screw-in muff for a counter-piston to go in place of spark plug, adapted a bolt to screw into said muff as the counter-piston. Prolly shaved the cyl head as well IOT reach appropriate compression, as well - he doesn't tell.
Max CR with counter-piston screwed in completely is calcultimated to be around 21:1.
Fuel is 3/4 pump diesel, 1/4 gasoline; no info on 2 stroke oil (1:50 as per standard, I'd wager).
Engine governing is with carb and throttle plus adjustment of CR with the counter-piston.
10000 km claimed clocked.
No info on MPG (might be a bit lower than possible since he says he's overjetting the carb for cooling purposes).
Crankshaft and bearings are taken from a 70 ccm model so they can take the beating from such a high CR, but this may or may not be a necessity for you -depending on whether the low-end of your particular engine can take bigger bore cylinders than what you have installed. Many 50ccm 4stroke Chinese scooters are known to be upgradeable to 100 ccm(keeping same CR) without crankshaft upgrade, so look up whether your 2strokes also can. Or you down-grade from a bigger bore to something your engine's crank can handle.
Myself, I have a 4stroke only, which precludes me from conducting such experiments, with a pretty packed cyl head and whatnot, but I may buy myself a 2stroke engine sometime in future just to test it myself.
Have a day
The scooter he used appears to be a 49cc Honda Spree. They use oil injection so that would take care of the lubrication needs.
Oh, that's dandy. And there I thought how he might be running WMO without any additives AT ALL
I like what that guy in Ukraine has done. I also would like to duplicate it as I have a junk Spree engine collecting spiders in my shed. My problem is I would like to do alot of things..... but time and $ are conspiring against me.
QUOTE]
Don't give up. Maybe you're not facing any great expenditures at all if you want to try this.
Do you value that little Spree engine of yours? Have any immediate plans for it? If not, off with its head, out with the plug and in with a bolt, I say
For some encouragement:
I, for one, am not at all convinced that guy did actually NEED to replace his scoot's crank with a sturdier one. Engine low-ends of variator-driven small-displacement scooters are often made with quite a wide range of displacement in mind. In China, Thailand, India and so on these same engines as sold as 50 ccm in States and Europe run with 60-90 ccm without hassle.
The following is only tangentionally related to your Spree engine, since it is not Chinese and also not a 4stroke, but it should illustrate the situation pretty good:
I'll repeat, my own Chinese 4 stroke runs 80 ccm on an otherwise stock 50 ccm low-end and under the same stock cylinder head.
Thus, not only is the piston area increased more than 1.5 times but also the compression ratio has risen from (dunno exactly - 7.5:1? 8.1:1? let's take the bigger figure for safety's sake even though I'm sure it is the first) to 11:5, so also almost 1.5 times more. This makes very roughly and at the very least for1.8 times more peak force upon the piston, small end and big end, the majority of that increase coming from increased bore (peak combustion pressure rising slower than corresponding compression ratio).
More: 100 ccm cylinder kits with a bigger head resulting in stock 7.5:1 CR are available (at least in Ukraine) for these same 149QMB engines, so the total peak force can safely be doubled as compared to stock. Crank bends and breakage are not reported, at least as far as I have read and heard so far.
(In fact, I am biting my own ass for not having bought such a kit for cheap money during my last stay over there. 16:1 compression under stock head, thick gasket against valve-on-piston collision, iridium plug, high-power coil, pure ethanol goodness against detonation - only true diesel can be even more frugal and efficient
Goddamn. Now I need to know what maximal cylinder bore can be stuck on a Hercules Prima GT moped without crank breakage. The one standing in my dad's garage with slim chances of a soon restoration and without papers or a key is as close as I get to a 2stroke for CI experiments, right now...
