2-stroke questions..... dont understand some things.

[x2468]

okay so it seems there are some things about 2-strokes that i wasn't aware of when i bought a 2-stroke. for one, i keep hearing that you cant go wide open on a 2-stroke. something about no lubrication and melting the piston. but that doesn't make sense because i see videos of people going wide open all the time in dune videos and drag race videos. and what if ur going down a straight road? doesn't seem to make sense.

anything else weird like that about 2-strokes i should know? i mean b4 today i never would have guessed you couldn't just hold the gas on a bike. it sounds so stupid.

[wr4life]

they tend to heat up since the fuel and oil is getting in and out of the motor so quick. my friends when they are wide open down roads will tend to hit the kill switch and artifically flood the motor while staying on the gas. that way the gas and oil mixture floods in and cools it down. but i dont know much about two strokes so take ti for what it is worth ?

[Kev_XR]

Wide open for extended periods.

[rmz757]

i havent ever heard that. i have heard that if you run out of gas while wide open you will sieze it up because there will suddenly be no oil into the cylinder, but thats all. chances are, unless youre wide open for long periods of time (like miles and liles at a time) youll have no problems.

[seehenry]

It is really bad to take a WOT run and cut the throttle. I seized a couple bikes when I was a kid that very same way.

[Dauntae]

Unless your in the desert you most likely won't be wide open for any leangth of time, Being wide open in fith gear can get rather fast and there are not too many places to do that, I've only done it once on a 2 mile streatch on a tar road and that road went by quick, Not too many places in the north east for us to open them up, I don't have many places I can get out of third on because there are way too many trees.

Dauntae

[mikecc]

It is really bad to take a WOT run and cut the throttle. I seized a couple bikes when I was a kid that very same way.

I wasn't WOT, but I ran out of gas in the meat of the powerband on my 2003 KX250, and I just had to put more gas in, and it started right up.

[realuser]

I dont see it as to be a problem. (wierd sentance) Im always wide open on my 85 and dont have problems. And i get to the top of fifth gear very often but when i do max out i usually kinda worry and let off the gas every few seconds.

[Doug.]

You can learn the basics (and sometimes more) about anything if you go to this site:

http://www.howstuffworks.com

Doug

[YZBrad]

they tend to heat up since the fuel and oil is getting in and out of the motor so quick. my friends when they are wide open down roads will tend to hit the kill switch and artifically flood the motor while staying on the gas. that way the gas and oil mixture floods in and cools it down. but i dont know much about two strokes so take ti for what it is worth ?

Thats what I do if I have to be on the gas for long periods of time. Usually I trey to short shift though, hopefully extending my top ends life.

[yamaha_rulez_125]

put it this way..you can go WOT but not for long periods of time (miles and miles)

i mean you can seize any engine if you go WOT for miles and miles

but yeah WOT on a 2 stroke is no problem if you keep it controlled. ?

[TwistiT]

the only problem is taking it off WOT, as the engine gets its lube from the gas. When the engines doing 12000rpm and the gas gets shut off, the pistons without lube for quite a few cycles, until the throttles back on. This is how they seize. When i had my old 2, i made sure to pull the clutch in when i backed off..... learnt the hard way.

[RayIn]

the only problem is taking it off WOT, as the engine gets its lube from the gas. When the engines doing 12000rpm and the gas gets shut off, the pistons without lube for quite a few cycles, until the throttles back on. This is how they seize. When i had my old 2, i made sure to pull the clutch in when i backed off..... learnt the hard way.

When wide open for extended periods - every so often pull in the clutch and blip the throttle a few times - then resume.

Regarding hitting the kill switch - good idea with respect to getting more lube in - but here's the problem: when you let off the kill switch with the throttle on, it puts sudden stress on the engine - particularly bottom end/primary gear. So this isn't recommended.

[x2468]

alright. because me and my friends take some back road pavement/dirt road excursions to get to trails. never more than a few minutes. but sometimes we go out to this one streach of pavement out in the back farm roads thats perfectly straight for about a mile maybe mile and a half. so we use that to drag race for fun. they think their quick on thier 450 quads but i haven't had the chance to take the KX out there. im pretty sure the Kx will eat the quads for breakfest, but then i got confused with this WOT issue and wondered how im gonna win down a straight-a-way if i cant hold the gas steady without melting the piston.

thanks for the tip Twist about holding in the clutch when i get off the throttle. i usually to that so the motor doesn't wine on downshifts, but sometimes since im used to fourstroke engine breaking i forget to. ill have to remember from now on.

[x2468]

now i have a question. why does the 2-stroke mixed gas cease to lubricate the motor when held at a constant RPM? why is it only lubricated when RPMs are varried? what is it that allows 2-stroke snowmobiles to run WOT forever? because ive seen those 2-stroke snowmobiles down frozen lakes and through some of the perfectly straight groomed snowmobile trails. is it a property of their oil injection?

[Motocross26]

You'll be fine, don't worry about it. Most people ride their small bore two strokes WFO all the time. Go find a video of an 85 race, those kids pound on their bikes. Going wide open for extended periods of time will, possibly, seize your engine though. If you hold it open for too long the exhaust port temperatures will get to hot and melt the piston.

Don't worry about it too much, though. These engines were designed to be beat on and they can take it.

[crrider491]

you can holed 2 strokes wide open ?

[Kev_XR]

the only problem is taking it off WOT, as the engine gets its lube from the gas. When the engines doing 12000rpm and the gas gets shut off, the pistons without lube for quite a few cycles, until the throttles back on. This is how they seize. When i had my old 2, i made sure to pull the clutch in when i backed off..... learnt the hard way.

Interesting.

Didn't the old KX500 have the choke attached to a small lever, like the comp release on an XR, so the rider could richen up the fuel on occasion when going full throttle across the desert?

[Bigcr]

If you are jetted properly, you can run WOT.

[kx_rider53]

If jetted properly it shouldnt be a problem. If you are a little lean to begin with then it can be a problem. Around any track, its fine. Desert riding is the only time you need to even think about it. Therefore, when you go desert riding, you make the main jet richer.