Thanks for the tip! I tried 1 1/2 capfuls of regular hardware-store acetone in my 1/2 gallon tank, and am pleased with the results. No more 4-strokeing, WAY nicer high-end, but lost a little hill-climbing power. I'd say it's a keeper...
An acetone success
- Thread starter Flapdoodle
- Start date
arceeguy
Active Member
Personally, I would not want to put a powerful solvent like acetone in my fuel. Especially with a two stroke engine because lubrication is delivered by the fuel. A cap and a half of acetone in a tank is a considerable amount when you take into account that there probably isn't much more oil per tank.
I believe the acetone myth was debunked by the Mythbusters, and acetone use in cars is being blamed for premature injector and fuel pump failures.
I believe the acetone myth was debunked by the Mythbusters, and acetone use in cars is being blamed for premature injector and fuel pump failures.
Actually, at 16:1, which is what I'm running (fairly new motor) there's 4oz. of oil in the tank, while the 1 1/2 capfuls of acetone represent 1/3 of an ounce. Gasoline is a powerful solvent too.
The point is that it works in this very simple 2-stroke engine with very low compression (6:1). There is a noticeable and instant performance difference.
Someone mentioned earlier in this thread that acetone in your fuel tank works similar to a drop of soap in a huge bowl of water with pepper sprinkled on top (all the pieces scatter to the sides). The fuel/oil mixture atomizes more easily, and therefore burns quicker. It's like lowering the octane rating of the gas, which is ok here, but probably NOT for your car or your Harley Davidson!
Flapdoodle
Member
Gasoline is also a lousy lubricant. When I worked in diesel power plants in the Air force, we were told gasoline could be used in a diesel in an emergency if oil was added. Else, the fuel pumps and injectors would seize due to lack of lubrication.
arceeguy
Active Member
The problem with acetone's solvent capabilities are that it dissolves plastics and is used as an industrial degreaser. It destroys fuel pumps by attacking the insulation in the armature windings, and destroys the composite fuel injector bodies.
Even in a small utility engine, it may have detrimental long term effects on the plastic float, needle valve, and rubber crankshaft seals.
I do not doubt that you saw a performance increase. I just wonder to myself "at what cost to longevity and durability?" - that's all.
I'm thinking that a great way to increase the performance of these engines can be had by replacing the simple (yet effective) stock carburetor with a more sophisticated Dellorto or Mikuni style motorcycle carb.
I am working on a Honda based CDI ignition setup that should offer easy starts and better performance because it has a MCU with ignition advance.
You're probably right about long-term effects-- even things like the fuel valve and hose could eventually fail as well. I'm just messing around with this one, trying to see what I can do for no money. Performance gets expensive (expansion chamber, carb, ignition, NOx, gearing, clutch, etc.)
I have already modified the muffler (but kept the catalyst), took a plug wire from an old Saturn, and bought a new spark plug. Next, I will probably sand about a millimeter off the top of the cylinder for more compression. While I'm at it, I am also going to take a dremel to the ports and clean things up a bit (but probably not change the port timing).
I've done the performance thing before, where each improvement comes at its price, but this is not going to be one of those projects.
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arceeguy
Active Member
It's only natural for tinkerers like us to want to "make it go faster!" - whether it be fuel additives, free flow air filters and exhausts.
I view these imported engine kits like I view the original VW beetle, a model of simplicity that is engineered to do the most with the least. Functionality first, and performance last.
I believe that we can get considerably more power without porting, or touching the exhaust system. The two weak points IMO are the fuel and ignition system. While the stock pieces are inexpensive, simple and functional - they aren't optimized for performance out of the box. I have found that the carbs tend to run too rich on the low-mid range, and they lean out at high revs - which is deadly in a two stroke. The stock CDI does not seem to have any spark advance designed into it.
The carb can be made better by lowering the main metering needle to help lean the low-mid range, and drilling the main jet with a miniature drill (by hand!) to enrich the mixture at high engine speeds. I purchased a miniature drill bit set for about $15, and enlarged the main jet one size.
This greatly reduced the four cycling at part throttle, and the flat spot near WOT. The engines runs cooler, and have much better throttle response. The 50cc models don't seem to need the main jet drilled, but the 66cc models benefit greatly from this mod.
The ignition mod I am working on involves using a standard CDI unit designed for Honda style pit bikes. I plan on rigging a magnet and coil to trigger the CDI unit and provide adjustability of the base timing.
Stage 3 would involve adapting a "real" motorcycle or scooter carb to provide more tuning options. (main jets, pilot jets, etc)
After that - then I would consider messing with porting and exhaust mods. To me, it doesn't make sense to modify ports or exhausts when there is much to be desired from the carb and ignition.
I view these imported engine kits like I view the original VW beetle, a model of simplicity that is engineered to do the most with the least. Functionality first, and performance last.
I believe that we can get considerably more power without porting, or touching the exhaust system. The two weak points IMO are the fuel and ignition system. While the stock pieces are inexpensive, simple and functional - they aren't optimized for performance out of the box. I have found that the carbs tend to run too rich on the low-mid range, and they lean out at high revs - which is deadly in a two stroke. The stock CDI does not seem to have any spark advance designed into it.
The carb can be made better by lowering the main metering needle to help lean the low-mid range, and drilling the main jet with a miniature drill (by hand!) to enrich the mixture at high engine speeds. I purchased a miniature drill bit set for about $15, and enlarged the main jet one size.
This greatly reduced the four cycling at part throttle, and the flat spot near WOT. The engines runs cooler, and have much better throttle response. The 50cc models don't seem to need the main jet drilled, but the 66cc models benefit greatly from this mod.
The ignition mod I am working on involves using a standard CDI unit designed for Honda style pit bikes. I plan on rigging a magnet and coil to trigger the CDI unit and provide adjustability of the base timing.
Stage 3 would involve adapting a "real" motorcycle or scooter carb to provide more tuning options. (main jets, pilot jets, etc)
After that - then I would consider messing with porting and exhaust mods. To me, it doesn't make sense to modify ports or exhausts when there is much to be desired from the carb and ignition.
Flapdoodle
Member
I tried lowering the needle; it made 4 stroking a little less. Then I reduced the main jet from .028" to .024". That made most of the 4 stroking go away. The needle is back where it was at 2nd from the top. Acetone got rid of most of the rest of the 4 stroking. Lowering the needle back to the highest notch was the last thing I did. The air filter is stock black plastic.
Every engine will respond differently. Altitude play a major part. One thing I will bet is that the ignition timing varies from engine to engine. (Mine is the common Chinese 80cc)
arceeguy
Active Member
Yes, every engine is a little different and air density plays a major part. Altitude along with ambient temperature can mean the difference between a good running engine and a seized up engine. I have found that the 66cc (80cc) kits consistently lean out at WOT/high revs when the temperature is below about 70F where I live. (at or not much above sea level) The 50cc kits do not seem to behave this way. Maybe it is because the exact same carb is used either kit, with the main jetting being optimized for the 50cc engines? I suppose some engineer in China knows for sure!
The ignition timing probably varies from engine to engine due to tolerances in the electronic components in the CDI module, but are apparently tight enough for the engines to run acceptably. I will be using a degree wheel and timing light to document what seems to work best.
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