Two stroke run backwards

just James
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just James
Edited Date/Time 6/5/2013 3:25pm
Once had my '79 CR250 start backward. I guess it bounced back just right off of the compression. Although I realize that a two stroke doesn't care which direction it turns for intake and exhaust, I was surprised that it would have ignition.
Curious if this has happened to anyone else on here.
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Radical
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Radical 6/4/2013 9:02pm
6/4/2013 9:02pm
I don't remember how it happened, but I did have a 2 stroke run backwards once. Surprised me.
Knobbyjake
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Knobbyjake 6/4/2013 9:59pm
6/4/2013 9:59pm
I had my '75 Penton 250 run backwards on me twice at dead engine start hare scrambles. Pretty surprising when you kick it over and drop the clutch and it takes off backwards on you. Almost ran my dad over the first time. After the second time we retarded the ignition a little and that stopped it.
dboivin
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dboivin 6/4/2013 10:11pm
6/4/2013 10:11pm
ski-doo took that little hiccup and made it RER. brilliant.
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MR. X
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MR. X 6/5/2013 2:46am
6/5/2013 2:46am
My polaris runs backwards when i want to go in reverse , same as the ski-doo.

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zookie
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zookie 6/5/2013 6:21am
6/5/2013 6:21am
Yea! Pretty cool that two strokes can do that. Only ignition timing suggests engine direction.

A lot of snowmobile engines run backward all the time so they can go in reverse! With direct injection, it is "easy" using software for a button press to slow the engine down enough where they can bump it in the wrong direction. They get it to run backward without ever shutting it off! Press the button again and it bumps forward! Pretty darn slick!!!
pete24
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pete24 6/5/2013 6:30am
6/5/2013 6:30am
when you shut your engine off, as it comes to a stop the last rotation cannot overcome compression so is goes backwards just a little, that must have something to do with how Rotax invented the reverse , but i do know for sure that i used to roll my chapparal 80 down my driveway in reverse bump start it and try to ride it backwards, i said try, never really could
Ryno23
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Ryno23 6/5/2013 6:36am
6/5/2013 6:36am
Polaris and Skidoo does it with the capability of the electronic ignition and efi. The engine RPM drops to a point where the ignition and fuel delivery change to make it run backwards. Brilliant idea combined with the simplicity of the 2 smoker motor!
Henk_Zanting 6/5/2013 6:49am
6/5/2013 6:49am
has to do with ignition timing..

long time ago (90 or 91) Mike Healy was racing in Europe with KTM and i saw at a winter SX Mike at the gate leaving backwards when the gate dropped.. pretty ugly.. and for sure no holeshot..
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friday10
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friday10 6/5/2013 7:44am
6/5/2013 7:44am
Back in the 70's there was a national at Bay Mare Race Track here in Cali., Jimmy Weinert stalled his factory Yamaha right in front of me, He kicked it over and dropped the clutch and went backwards! He looks over at me like "WTF" . Funny as hell
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BobbyM
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BobbyM 6/5/2013 7:59am
6/5/2013 7:59am
just James wrote:
Once had my '79 CR250 start backward. I guess it bounced back just right off of the compression. Although I realize that a two stroke doesn't...
Once had my '79 CR250 start backward. I guess it bounced back just right off of the compression. Although I realize that a two stroke doesn't care which direction it turns for intake and exhaust, I was surprised that it would have ignition.
Curious if this has happened to anyone else on here.
Yamahas...factory included did that back in the 70's. The jammer had it happen at hangtown 78 or so. The look on his face when he popped the clutch was price less. Hit a water hole and doused his scooter completely.
BobbyM
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BobbyM 6/5/2013 8:01am
6/5/2013 8:01am Edited Date/Time 6/5/2013 8:22am
friday10 wrote:
Back in the 70's there was a national at Bay Mare Race Track here in Cali., Jimmy Weinert stalled his factory Yamaha right in front of...
Back in the 70's there was a national at Bay Mare Race Track here in Cali., Jimmy Weinert stalled his factory Yamaha right in front of me, He kicked it over and dropped the clutch and went backwards! He looks over at me like "WTF" . Funny as hell
Wrong track I think....nope I think yer right. Happened there and at Hangtown.
Spartacus
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Spartacus 6/5/2013 8:01am
6/5/2013 8:01am
Had a Bultaco do that once. Sure surprises you when you let out the clutch.
twosmoke30 6/5/2013 10:06am
6/5/2013 10:06am
my dads friend had a old cr480 and every now and then the compression from it would make it start up backwards. you dont know fear until you wack open the throttle and then your face is on the front fender. It was fairly common apparently with the older bikes, until they made a one-way mechanism to keep it from happening
WhKnuckle
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WhKnuckle 6/5/2013 10:29am
6/5/2013 10:29am
I remember one time after a race and we were all sitting around hitting the tequila pretty hard, and my bike ran backwards. Come to find out I was sitting backward on the seat.
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AJ
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AJ 6/5/2013 10:34am
6/5/2013 10:34am
just James wrote:
Once had my '79 CR250 start backward. I guess it bounced back just right off of the compression. Although I realize that a two stroke doesn't...
Once had my '79 CR250 start backward. I guess it bounced back just right off of the compression. Although I realize that a two stroke doesn't care which direction it turns for intake and exhaust, I was surprised that it would have ignition.
Curious if this has happened to anyone else on here.
Yes on my 500 playing with advancing the timing a bit too far,, it could run fine, then going into a corner on decell
it could backfire , and when you went to accelerate thru the corner it was running backwards ..

and running just as strong as fowards
BRAAAP!!

LOL
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vet323
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vet323 6/5/2013 11:52am
6/5/2013 11:52am
The neighbor kid had a clapped-out, stripped Kawasaki KE125 and we used to ride everyday. There was a hill near the house with a small jump on it, he went too hard and landed on the upper part of the hill at a dead stop, stalling the engine. He just about dumped the bike, but got under it and lifted it back up. While attempting to restart it he pulled in the clutch, the bike started rolling downhill, he accidentally popped the clutch and the engine caught while he was back pedaling as fast as he could. After throwing a little roost, he launched it backwards over the same jump, then crashed hard at the bottom. To add insult to injury, after the bike tipped over it started on fire.

Still the funniest thing I have ever seen in person, RIP Bart!
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lumpy790
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lumpy790 6/5/2013 12:57pm
6/5/2013 12:57pm
saw a Maico blast back into the fence behind the start after the gate dropped once..... poor guys nads around the gas cap.
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just James
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just James 6/5/2013 1:04pm
6/5/2013 1:04pm
vet323 wrote:
The neighbor kid had a clapped-out, stripped Kawasaki KE125 and we used to ride everyday. There was a hill near the house with a small jump...
The neighbor kid had a clapped-out, stripped Kawasaki KE125 and we used to ride everyday. There was a hill near the house with a small jump on it, he went too hard and landed on the upper part of the hill at a dead stop, stalling the engine. He just about dumped the bike, but got under it and lifted it back up. While attempting to restart it he pulled in the clutch, the bike started rolling downhill, he accidentally popped the clutch and the engine caught while he was back pedaling as fast as he could. After throwing a little roost, he launched it backwards over the same jump, then crashed hard at the bottom. To add insult to injury, after the bike tipped over it started on fire.

Still the funniest thing I have ever seen in person, RIP Bart!
Sounds like that bike had had enough of his crap.
Too funny!
dboivin
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dboivin 6/5/2013 3:01pm
6/5/2013 3:01pm
MR. X wrote:
My polaris runs backwards when i want to go in reverse , same as the ski-doo.
polaris bought rights for the technology from ski-doo early on knowing it was gonna be a key player in sled industry. This is also a major factor in ski-doo holding on to and developing the 2stroke motor. 4 strokes are stuck using clumsy mechanical reverses that have proved to be problematic and add weight.
MR. X
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MR. X 6/5/2013 3:11pm
6/5/2013 3:11pm
MR. X wrote:
My polaris runs backwards when i want to go in reverse , same as the ski-doo.
dboivin wrote:
polaris bought rights for the technology from ski-doo early on knowing it was gonna be a key player in sled industry. This is also a major...
polaris bought rights for the technology from ski-doo early on knowing it was gonna be a key player in sled industry. This is also a major factor in ski-doo holding on to and developing the 2stroke motor. 4 strokes are stuck using clumsy mechanical reverses that have proved to be problematic and add weight.
Ya , i remember when polaris started using it in around 04 and the deal was some kind of patent trading went on between the two , ski doo wanted to use something from polaris rear suspension and poo wanted push button reverse , and cat is still trying to figure out how to put reverse on a trail sled.
Brackis
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Brackis 6/5/2013 3:24pm
6/5/2013 3:24pm
Happened to me on an IT 175. Sheared the flywheel key and when did it ran backwards. Didnt run good though
dboivin
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dboivin 6/5/2013 3:25pm
6/5/2013 3:25pm Edited Date/Time 6/5/2013 3:26pm
MR. X wrote:
My polaris runs backwards when i want to go in reverse , same as the ski-doo.
dboivin wrote:
polaris bought rights for the technology from ski-doo early on knowing it was gonna be a key player in sled industry. This is also a major...
polaris bought rights for the technology from ski-doo early on knowing it was gonna be a key player in sled industry. This is also a major factor in ski-doo holding on to and developing the 2stroke motor. 4 strokes are stuck using clumsy mechanical reverses that have proved to be problematic and add weight.
MR. X wrote:
Ya , i remember when polaris started using it in around 04 and the deal was some kind of patent trading went on between the two...
Ya , i remember when polaris started using it in around 04 and the deal was some kind of patent trading went on between the two , ski doo wanted to use something from polaris rear suspension and poo wanted push button reverse , and cat is still trying to figure out how to put reverse on a trail sled.
yea poor cat. 12' turbos had a recall because they would get stuck in reverse permanently. lol.

yeah ski-doo and polaris sue each other each time they want some technology from each other...then they negotiate a deal where they take something from each other. another one going on right now over frame geometry.
Ryan_Glatz
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Ryan_Glatz 12/14/2018 3:41pm
12/14/2018 3:41pm
Polaris 400l doing it right now running backwards then hiccup and run fowards...... No matter where I set the ignition timing it still does it. New cdi and still doing it......
EZZA 95B
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EZZA 95B 12/14/2018 4:33pm
12/14/2018 4:33pm
Happened to one of my mate's '98 CR 125's, the thing had a fair bit of work done to it. There were quite a few jokes made after that.Laughing
NorCal 50+
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NorCal 50+ 12/14/2018 4:54pm
12/14/2018 4:54pm
I thought this was a joke at first- 40 years of riding and I have never, ever heard of this. Woohoo
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UGOTBIT
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UGOTBIT 12/14/2018 5:26pm
12/14/2018 5:26pm
Friend had a KTM 125 that did this quite often
Shawn142
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Shawn142 12/14/2018 6:43pm
12/14/2018 6:43pm
Had this happen on the line with a '94 CR125. Clicked into 1st and the bike tried to roll back out of the starting line.
drt410
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drt410 12/14/2018 6:50pm
12/14/2018 6:50pm Edited Date/Time 12/14/2018 6:55pm
just James wrote:
Once had my '79 CR250 start backward. I guess it bounced back just right off of the compression. Although I realize that a two stroke doesn't...
Once had my '79 CR250 start backward. I guess it bounced back just right off of the compression. Although I realize that a two stroke doesn't care which direction it turns for intake and exhaust, I was surprised that it would have ignition.
Curious if this has happened to anyone else on here.
How long? If its pulling the intake air through your exhaust and spitting exhaust out through your carb its going to be getting no fuel and Id be surprised if the exhaust going through the carb/fuel doesnt cause a fire.

Is it doing this or is the rod just coming down the opposite direction over the crank and the engine still works normally?
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