Crazy CR problem...new reverse option?

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#1
My buddies bike (03 CR250) is randomly going into reverse when shifted into first gear. All I could do was laugh :) but I hope someone can give me some insight as to what might be happening. He said it's after it warms up, and when he puts it in first to take off, sometimes it goes backwards. I can't stop laughing about this! :) Any info appreciated!
 
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#2
I've heard of this happening back in the '70s when the bike would be kicked started and the crank would actually revolve in the wrong direction. :eek: I haven't heard of it happening in modern days tho. Does he have to shut off the bike and restart it after this happens?
 

KiwiBird

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#3
This is generally a timing problem. Possible problems might be -
- Slipped flywheel because of broken locating key (woodruf key) in crank.
- Bad CDI box
 

a454elk

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#4
Try this, look down and count the wheels, if you see more than 2, it may be that new CR quad. LOL
 
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#6
Now I'm laughing harder! Thanks for the funny replies (and the serious ones)! I don't know why this strikes me as so funny, but I can't quit laughing about it. On a serious note though, I thought the same thing about the motor starting in the wrong direction, like a kickback when he kickstarted it. But it's not, the bike will be running fine, and then he'll just go to take off and it goes backwards. He has to shut it off and restart to get it to go forward again. I had no idea timing could do this though. I don't quite understand it, but we'll look into it. Thanks again for the replies!
 

dirt bike dave

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#7
Some modern snow mobiles are designed to run in reverse when you back up. Computer changes the timing when reverse is activated.

I did a quick google search, and some old boat motors were configured to run the same way - turn the motor off, move the switch to reverse (changing the timing) and re-start. Instant backwards.

Most piston port two strokes are candidates for backward running. Rotary valve two strokes (old Can-Ams, etc...) are unlikely to run backwards.

Saw it happen inadvertantly to a friend with a '71 Husky 250. We'd heard about the possibility, and had a good laugh.

BTW, I think it is more likely to occur if the timing is too advanced.
 

viking20

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#8
Ive seen it happen a few times , timing is seriously wrong ,(after tdc),and just as the engine is about to stall,it starts to run backwards....
 
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#9
Here's some major info that I left out. This all started after doing a new top end (Wiseco). He told me last night that it kicks very hard, kicks back really bad, so bad in fact that last time he started it, it actually broke the kickstarter off at the knuckle. He said the rebuild went very smooth though, and the bike runs excellent. The Honda dealership said it could be that the bike hiccups at idle causing the engine to run in the opposite direction. From everything he's said, that sounds logical to me. Could something have gone wrong on the rebuild to cause this?
 

fender92883

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#10
Well, at least he wasn't lined up at the starting gate of an MX race...that would REALLY have been embarrassing! I could just see it...leaning way forward, revving up the engine to get ready for the gate to drop, dump the clutch and BRAAHP! ...instantly over the handlebars! :ohmy: Good luck getting that problem fixed!
 
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#11
fender92883 said:
Well, at least he wasn't lined up at the starting gate of an MX race...that would REALLY have been embarrassing! I could just see it...leaning way forward, revving up the engine to get ready for the gate to drop, dump the clutch and BRAAHP! ...instantly over the handlebars! :ohmy: Good luck getting that problem fixed!

Oh man I'm rolling on the floor after that reply. That would be freaking hilarious! I had my bike start backwards once after I didnt' make it up a hill and went ripping down it backwards. I dumped the clutch in an effort to slow down and it fired.. I hit the ground hard on that one....
 

marcusgunby

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#12
Check the woodriff key on the crank-this holds the flywheel in alignment-if it shears the timing will be way off.The kx500 is really bad for this problem but others may do it as well.
 
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#13
haha funny ****e!!!!
I had it happen to me on my old 78 YZ 80 bout 3 times when i was alittle tacker. The problem is either the CDI ( had a DT 200 do it at work one day from CDI) more than likely it may have the wrong piston put into it making the compression too much If hae has snapped kickstarts trying to start it there is somethign waaaaay wrong there. Im thinking when he kick it the compression is too much and the piston is forced down before it starts the bike fires at the time it starts to go down and the engine runs in reverse. I would replace the top end with another piston kit and see what happens then
 
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#14
I've had that happen on my 87 Husky 250 a couple times. It's left side kick and unless you get NINJA on that kickstarter and get er spinning the right way, it's gonna kick back due to the compression. I was all leaned forward and getting ready to head up the trail when that thing roosted underneath the bike and in front of me and I headed over the bars while the bike went backwards. From then on, I've always wondered which way the bike would go. Another funny thing that happened was when it pop started in reverse. I got stuck on a hill and it rolled back so to stop it I let out the clutch, WOW!!!!!!!! I always thought it would only happen on older bikes. My 77 Bultaco would run backwards too.
 

motometal

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#15
i would take out the spark plug, and turn it over slowly to feel if there is any mechanical resistance. If so, this is very bad. If not, then the resistance must be from high compression. He needs to take out the new piston and compare it to the old one. What if it was installed backwards? Just a thought, although I can't see where this would make it run backwards.