What is "Four-Stroking"?

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Colorado Mike
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What is "Four-Stroking"?

Post by Colorado Mike »

Okay, I know this will be tough to answer in a written form, but I keep hearing the term "Four Stroking" in the context of jetting the low to mid range of rpm. I don't know what this sounds like. Anybody think they can 'splain it to me?

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Mike

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Post by skipro3 »

I'll try:
To experiance 4-stroking, ride your bike at a moderate speed with load on the engine. Back off the throttle just enough to take the load off the engine. As you do so, the motor won't fire clean on every stroke of the piston, but instead, only fire on every other stroke; just like a 4stroke engine does. Open the throttle a bit again, and the 4stroke rattle goes away and a nice clean 2stroke exhaust note will return. If you just chop the thottle closed, the motor will not 4stroke because it has a load on it then too. Just that it is now a load working to slow down the bike, not speed it up.
Hope this helps!
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Post by canyncarvr »

Yup!

What Ski describes will happen with any 2-stroke, jetted properly or not.

As related to poor jetting you will hear 4-stroking when the engine is loaded up due to excessive fuel...like what most 2-strokes do if you leave the choke on too long. Heck...even if you DON'T leave it on too long the choke/cold/start sequence will usually involve some 4-stroking until the bike 'cleans out'.

It's that blubbering sound...........in any case caused by a 2-stroke NOT firing at every TDC event.

If you're going to be picky...the plug may indeed FIRE..but the mixture will be such that it won't LIGHT.

That warn't tough to 'splain. As long as it's not tough to unnerstan, we're good to go!

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Post by Colorado Mike »

Cool I get it..just one of those things you experience all the time, but had a different name for..like in my case.."loading up", or "runnin crappy".
Mike

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Post by canyncarvr »

'runnin crappy'...'4-stroking'???

Does that apply if it is REALLY a four-stroke? :wink:

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Post by skipro3 »

LOL!!

I'll have to tell my 4-stroke buddies that is the term used for a poor running 2-strokes. Bet they laugh too!
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Post by Colorado Mike »

uh, yeah, I think that fits. BTW, of the four guys I ride with most often, I'm the only 2 stroker left. Which means my bike takes about 40 times less kickstarts per day of riding than the next leading competitor. :lol: These guys get pissed when they see mine start on one kick from stone cold. :mrgreen: And the guy on the YZ426 can work himself into heart attack country trying to kick it over after he dumps it. I think I'll work on starting it with my hand just to watch the tops of their heads blow off...
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Post by KDXGarage »

I like to watch the SX and MX races and when the four stroke racers tip over and stall it, I love to scream, "KICK IT, YOU SOB!" at the screen.

Be sure to give 'er a little gas with one hand when cranking it with the other. That would kill them. :lol:
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Post by fuzzy »

Does that apply if it is REALLY a four-stroke?
IMO...HELL yes!
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Post by jackpiner57 »

Please try to get it on video! I will pay you good money for a copy :mrgreen:
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