KTM two stroke runs backwards!

62 replies to this topic
  • doggerdan1

Posted October 08, 2006 - 12:11 PM


Here's what I know about it so far. My brother was riding his 1988 ktm 500 and it was running fine. He starts it next time, lets out the clutch and it takes off in reverse. He did this several times and it finally started (the right way), rode it around a little and when he started to slow almost to a stop it started running backwards again. Anyone heard of this and know what causes it?

  • enduro4231

Posted October 08, 2006 - 12:19 PM


The only thing I can think of is that the kickstart gear somehow got screwed up so it spins the engine backwards when kicking. I say this, because the only way the engine will run in reverse is if it's started reverse.

  • FLboy

Posted October 08, 2006 - 12:21 PM


It could be that it kicked back on the compression stroke and actually started. I've seen 2 stroke model airplane engines do this, but never a 2 smoke motorcycle... but I don't see why it couldn't. I doubt seriously the kickstarter had anything to do with it... it doesn't reverse and then work again..

  • klxd

Posted October 08, 2006 - 12:25 PM


Lotsa 2 strokes designs can run backwards. I think only rotary valve types can't. It should have "kicked back" against the starter so maybe there is something going out on the ratchet mechanism if it kept running.

  • Beano

Posted October 08, 2006 - 12:28 PM


I've heard of guys running a banshees and other quads backwards so they can get a straight exhaust and air induction. but ever notice wit some 2strokes they can kick you back? My lt500 does it sometimes and man it HURTS!

  • doggerdan1

Posted October 08, 2006 - 12:35 PM


I wasn't there, but from what I understand it started running backwards before he had come to a complete stop, AFTER he had been riding it forward! :devil:

  • klxd

Posted October 08, 2006 - 12:41 PM


I just kicked back against compression and started. Maybe the timing is a little too advanced if it's adjustable. It's a warning not to slip the clutch on a dead engine for braking when backing down a hill.

  • Sub

Posted October 08, 2006 - 12:45 PM


The timing is off. It's not that big of a deal.

  • John_Curea

Posted October 08, 2006 - 12:57 PM


I had that happen on a '90 KTM300.....

I was riding on our test track a long time ago. I just about stalled it, I grabbed the clutch real quick to catch it from stalling. When I let the clutch out (I was still rolling forward) The bike acted like I was applying the brakes. When I came to a stop I let the clutch out and it started going backwards.

Of course I was riding alone and no one saw it..... :devil:

Pretty weird I thought.

  • doggerdan1

Posted October 08, 2006 - 12:59 PM


The timing is off. It's not that big of a deal.

Thats the only thing I can figure too. Maybe the flywheel key sheered?

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  • John_Curea

Posted October 08, 2006 - 01:03 PM


Maybe the flywheel key sheered?

I wouldn't think so, mine never missed a beat afterwards......

  • Herbs

Posted October 08, 2006 - 01:28 PM


Diesel motors have also been known to run backwards at times.

  • jkm712

Posted October 08, 2006 - 01:30 PM


Timing issue. It's firing too close to / or at - top dead center.

  • boomman

Posted October 08, 2006 - 02:04 PM


I say adjust your riding style to fit your new bike attitude!

  • DethWshBkr

Posted October 08, 2006 - 02:55 PM


KTM - so fast, they can go BACKWARDS!

Alessi will be lined up on the gate facing the wrong way next year and still pull a holeshot!

I think someone made a post of this a few years ago - so yeah, just timing.

  • MrSmooth

Posted October 08, 2006 - 03:25 PM


I've seen several 2 stroke trials bikes run backwards for a second or two.

  • dezryder

Posted October 08, 2006 - 03:57 PM


I thought I was the only one!

On my '83 Husky 500xc I had that happen in the middle of a stream crossing! (Good laugh for my ridding buddies) I glanced off a submerged rock throwing me off balance and chopped the throttle and pulled in the clutch, turned the bars hard to regain balance while letting the clutch and tweaking the throttle all at the same time. Almost went over the bars and fell in to drown the bike and myself. :devil: x2

Had it kickstart backwards a couple times too. You have no clue until you let the clutch out. :thumbsdn:

Just the other day I read that 2-strokes by design, can run in either direction.

  • Mike in Fresno

Posted October 08, 2006 - 06:44 PM


In 1972 I had a 70' 405 American Eagle, a Husky 8spd enduro copy, It was timed at top dead center. It would kick back so hard that I ripped the sole on my tennis shoes once, tore thru my sock and bruised my foot. It too would start backwards once in a while and you couldnt tell until you let the clutch out. So I think that its a fluke or something has slipped, either the plate came loose or key started to shear.

  • dezryder

Posted October 08, 2006 - 07:57 PM


Mike in Fresno,

You notice that it's big bores chiming in on this subject. I personally feel that it's not a timing issue, (at least in my case) but the inertia of the engine. IE, major crank weight spinning and you almost stall. The stall point happens to be at the precise firing point of the engine BTDC...hence making it fire and propell the piston backwards reversing the rotation.

Let me rephrase: timing is an issue with bikes that are timed very close to TDC. That coupled with the fact that there was this considerable mass rotating in my 500, was the reason for my backwards motion. I didn't change anything because everything was spot on and the bike hauled azz.


  • dezryder

Posted October 08, 2006 - 08:29 PM


Considering the source (Yamahahaha owner), I don't think anybody took offense.

Ifin ya wants to get down and dirty, it's actually 'Yamamaha'. :devil:


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