Maintenance & Technical > KX500 Original

Useful Info for Two Stroke Tuners

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Minnetonka_Mark:
I want to direct all you 2-stroke tuners to an article about an experimental big bore 2-stroke dirt bike engine developed by Honda.  This is NOT a new engine or article.  It is from a few years ago.  

In any case the article is especially useful to KX500 tuners because it explains inherent problems with the standard 2-stroke engine's combustion cycle.  The article helps me to understand some of the difficult to interpret behavior observed when comparing various jets, etc...  

Here is a one paragraph excerpt:
At small throttle openings, a conventional two-stroke will start a repeating pattern of misfiring, which allows a large amount of unburnt gas and oil to be expelled directly into the atmosphere. At these low engine speeds, the amount of fuel entering the combustion chamber is small compared to the amount of exhaust remaining, which creates a mixture that is not ignited by the spark, and is expelled directly into the exhaust system. Each time this misfire occurs, the amount of fuel remaining in the cylinder increases, until it is great enough to be ignited by the spark. When it is ignited, the cylinder is again filled with exhaust and the cycle repeats itself. By measuring cylinder pressure over time, this cycle can be seen as a pattern of regular large increases in pressure. The increases in pressure mark the points where the mixture burns; between these pressure peaks is the area where all of the fuel and oil are going out the pipe without burning, which is a major source of emissions and exhaust system contamination. As can be seen from the graph below, this cycle occurs at low and medium loads during conventional two-stroke combustion.

Check out the article. :idea:

http://www.motorcycle.com/mo/mchonda/exp2_tech.html

doordie:
Minnetonka_Mark!

Yes, there we have the clue how to make the twostroke reduce emission and be competive to fourstrokes.
When we solved that problem we have all benefits from twostroke and little or no emission.
And we will never see a fourstroke more. :lol:  :lol:  :lol:

And you know guys, I repeting myself with the squishclearance,but it
works for emission too. :D  :D

KXcam22:
Doorde,
 I don't know if you remember the Orbital engine (australian I think)?  It was a high eff. multi-cylinder 2-stroke that was to revolutionize the auto world, then vanished.  I never knew where it went until I read a outboard motor brochure.  My neighbourhood is filled with 250hp multicylinder 2-stroke outboard engines most or all using orbital technology.  That is how most are California 2008 legal.  They must have got together as a group and bought Orbitals technology.  Neat! Cam.

mikesmith:
The EPA probally didnt like a clean 2 stroke.

doordie:
KXcam22,

I haven?t heard about this orbital engine.I will use the internet here and check it. :D

What?s EPA? :?

//doordie

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