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Four Strokes SUCK!!

by JohnNicholas on 09/24/2010

The basic explanation of how the internal combustion engine works, is the process of SUCK-SQUEEZE-BANG-BLOW. Simple explanation for a somewhat complex marvel of mechanical ingenuity .

One this site we have mentioned the four-stroke started off SUCKING and we’re right! They do SUCK before anything else.

1. INTAKE (SUCK) When the piston descends in the cylinder it creates a vacuum (thus the term SUCK for this cycle). And an air/fuel mixture is drawn into the cylinder.

2. COMPRESSION (SQUEEZE) As the piston ascends, the air/fuel mixture is forced into the small chamber machined into the cylinder head. This compresses the mixture (SQUEEZE) until it occupies 1/8th to 1/11th of the volume.

3. IGNITION (BANG) The air/fuel mixture is ignited (BANG) by the spark plug just before the piston reaches the top of its stroke. The heat produced by combustion increases the pressure in the cylinder, pushing the piston down with great force.

4. EXHAUST (BLOW) As the piston approaches the bottom of its stroke, the exhaust valve begins opening and the pressure in the cylinder begins to force the gasses out around the valve. The ascent of the piston then forces nearly all the rest of the unburned gasses from the cylinder (BLOW). The cycle begins again as the exhaust valve closes, the intake valve opens and the piston begins descending and bringing a fresh charge of air and fuel into the combustion chamber.

Now you know the reason for the farting popping noise of high-revving four-stroke engines. (Is that the worst sound in the world?)

Of course this is all in jest, but many people on both sides of the two-stroke vs. four-stroke debate have many differing opinions on this subject. It brings out powerful feelings in many.

In addition there are mis-conceptions about this site and the stance that it should take in this debate.

Stand back, he's gonna blow!!

It seems that guys that love four-strokes hope this site dies a quick and/or painful death (well at least some of them do! LOL) And stops all the “propaganda” about how great two-strokes are.

It seems as there are some that have no sense of humor.. when we call their bikes lawn tractors ( a 450F is the same displacement as my Sears Riding mower!) or when we tell them they require a huge handi-cap (displacement advantage)  in order to be competitive with a two-stroke they get upset and start calling people names.

Want some whine with that cheese?

Please go and get yourself a sense of humor…  :-)

At who's expense?

One the other hand there are folks on the pro two-stroke side of things that are way over the top. These are the folks who spew hate towards anything four-stroke (usually while driving/owning many items that are four-stroke. Including, cars, pick-up trucks, lawn mowers, generators) Usually yelling at the top of their lungs, “four-strokes must die!”

Honestly both extremes of the debate are just that… extremes. No matter what those on the fringes believe, four-strokes are here to stay, at least for a while. The same goes for two-strokes. The news of the two-stroke’s impending death is highly exaggerated.

So we have folks on both sides of the debate, so where in this lexicon does the TSM web site fall? Well certainly not in the middle!!

Since the very beginning we have talked about displacement parity. Fair rules that can provide great racing for the racer and fan alike. An opportunity for two-strokes to be competitive with four-strokes.

The way the rules in pro racing stand right now, leaning heavily toward the four-stroke, the lowly two-stroke is considered a joke.

What no one has been able to explain reasonably is why do the four-strokes deserve welfare? There have been tons of rumors, here-say along with marketing hype has obliterated common sense.

Talk about emissions killing off two-strokes was big news for a while, now there is less talk about it. The four-strokes, while better than the old style two-strokes in this regard, still have a long way to go. Rumors have been running rampant on the subject of Direct Injection (not to be confused with Fuel Injection) which promises to turn the two-stroke to the better option for emissions.

Another by-product of the four-stroke “revolution” is the noise factor. Tracks are being shut down at an alarming rate due to noise. The exhaust note of the four-stroke carries much further than the two-stroke making enemies of anyone within a mile or less of a race track. The loud pipes appear to be in the name of “improved” performance.

No... really?

Back to the original question what is TSM’s stand on the two-stroke vs. four-stroke debate? To the disappointment of the crazed two-stroke fan, we do not “hate” four-strokes. These machines are absolutely perfect for some racers. They are easy to ride and will last a reasonably long time if kept in a mild state of tune. Although they would be much better if they install quieter exhaust systems!

Yes, four-strokes are cool bikes!

The technology that has brought them to the state they currently are in is pretty cool. Just compare any of the new four-stroke motocross machines to the four-strokes of the past, no comparison in weight, power or handling.

There is NO way four-strokes should enjoy a displacement advantage that is double or nearly double that of a two-stroke. Let’s be sensible, use a little logic here, there would be NO four-strokes in motocross if it were not for the displacement advantage.

So what are we saying? Eliminate the displacement advantage which will allow racers to make a choice. Whether that choice is a two-stroke or a four-stroke, a racers choice will be based on factors other than “well the rules are unfair so why should I ride a two-stroke and get beat?”

Currently there is a petition being circulated to amend the rules in Pro Motocross racing. We believe in this idea and feel that it will help in our quest to bring two-strokes back into Pro Racing. If you have not doe so please take a moment to add your voice to the masses.

How long do I have to do this???

It has been made clear that none of the rule makers in Pro Motocross have any interest in equal displacement. So banging that drum over and over is a lost cause, at least at this time.

Our sport is shrinking. And seems to be doing so more and more every week. Instead of choosing motocross, potential new racers are deciding to invest their money in other sports. This does not bode well for the long term health of motocross.

The two-stroke vs. four-stroke debate is not the answer to all the sports woes and certainly will not fix all its problems. Something must be done to move our sport forward in growth.

Whether that means signing a petition, buying a two-stroke, starting a new series or one of millions of things that could be done.

Each one of us is responsible in the quest to improve our sport, turn it around into growth and health.

What are you going to do?