07 yz450f locked up


14 replies to this topic
  • DevonJarrett

Posted July 28, 2008 - 12:59 PM

#1

at my last race i was goin around a corner in 3rd gear and i crossed rutted, bobbled a little but and stalled the bike and when i tried to kick it the kickstarter wouldnt go down, so i pushed it off the track and about 5 minutes tried to start it again and it finally went down and started, anyone have any idea what couldve happened? I change my oil and oil filter after every race.

  • DMC707

Posted July 28, 2008 - 01:11 PM

#2

at my last race i was goin around a corner in 3rd gear and i crossed rutted, bobbled a little but and stalled the bike and when i tried to kick it the kickstarter wouldnt go down, so i pushed it off the track and about 5 minutes tried to start it again and it finally went down and started, anyone have any idea what couldve happened? I change my oil and oil filter after every race.



That happened to me on my '08 with maybe 2 hours on it at the time --- i had been stalling it all day --- it didn't do any damage

  • clutchless

Posted July 28, 2008 - 01:26 PM

#3

at my last race i was goin around a corner in 3rd gear and i crossed rutted, bobbled a little but and stalled the bike and when i tried to kick it the kickstarter wouldnt go down, so i pushed it off the track and about 5 minutes tried to start it again and it finally went down and started, anyone have any idea what couldve happened? I change my oil and oil filter after every race.


you piston is stuck at the very peak of the stroke and your kickstarter is stuck at vertical with full compression built up, so you can't get good leverage on it.

you have to lean forward on your bars and kick the kickstart lever back twards your rear tire to free it with the hotstart lever pulled in.

hint to solve: don't stall... you may be stalling due to the wrong jetting so check that. you can't lug the rear tire through loose soil on a 450 as easily as a 2stroke or a 250f, be sure to pull the clutch in these situations and feather it a bit on your exit of the corner, or take the corner with more speed so you don't stall.
:ride:

  • DevonJarrett

Posted July 28, 2008 - 02:27 PM

#4

I'm hoping it was something simple like that, thanks for the quick replies guys, and yeah i know i suck at corners, but there was a triple right out of the corner and it was 3rd gear pinned haha

  • clutchless

Posted July 28, 2008 - 02:34 PM

#5

I'm hoping it was something simple like that, thanks for the quick replies guys, and yeah i know i suck at corners, but there was a triple right out of the corner and it was 3rd gear pinned haha


my bike did this yesterday came into a corner super hot on both breaks, tried to engine break a little in super soft sand without the clutch pulled in and it stalled right before a hill.

the first time it happened was in a race. i freaked and rode cautiously the rest of the ride thinking my bike would grenade.

changed the oil and filter and it was clean as ever. no metal flakes or signs of breakage.

  • Nitrox

Posted July 28, 2008 - 03:28 PM

#6

I've also found that if I can just get the bike to roll a bit and pop the clutch it will be enough to get it off of the peak of the stroke. It usually doesn't take much.

cb

  • grayracer513

Posted July 28, 2008 - 03:34 PM

#7

The piston is not stuck anywhere. What happened is that the engine stalled against the full compression stroke so abruptly that the auto decompression pin didn't have a chance to redeploy. It's just like having an older 426 without a compression release.

Put the bike in gear and pull it backward a little ways to release the decomp pin and restore normal operation.

Read:

http://www.thumperta...979#post5314979

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • clutchless

Posted July 28, 2008 - 03:46 PM

#8

The piston is not stuck anywhere. What happened is that the engine stalled against the full compression stroke so abruptly that the auto decompression pin didn't have a chance to redeploy. It's just like having an older 426 without a compression release.

Put the bike in gear and pull it backward a little ways to release the decomp pin and restore normal operation.

Read:

http://www.thumperta...979#post5314979


um yes the piston is stuck. thats why you can't kick it easily.

autodecom, does just that releases the pressure and allows the piston to become "unstuck" just like rolling it back.

thanks Gray(gottagetthelastwordandrepeatpointsmadeinadifferentmannortoproveubbercyberdorkknowlegde)Racer

:ride:

  • Justin89

Posted July 29, 2008 - 09:38 AM

#9

Your gonna argue with Gray...? wonder who will win:p :ride:

  • yzfjbw323

Posted July 29, 2008 - 06:18 PM

#10

um yes the piston is stuck. thats why you can't kick it easily.

autodecom, does just that releases the pressure and allows the piston to become "unstuck" just like rolling it back.

thanks Gray(gottagetthelastwordandrepeatpointsmadeinadifferentmannortoproveubbercyberdorkknowlegde)Racer

:ride:


This guy has spheres of steel.
In the words of some Japanese military captain sometime in 1942 "Why would you wake a sleeping giant?"

  • Whyzee429

Posted July 29, 2008 - 06:23 PM

#11

Lmao!

  • KJ790

Posted July 29, 2008 - 07:38 PM

#12

um yes the piston is stuck. thats why you can't kick it easily.

autodecom, does just that releases the pressure and allows the piston to become "unstuck" just like rolling it back.

thanks Gray(gottagetthelastwordandrepeatpointsmadeinadifferentmannortoproveubbercyberdorkknowlegde)Racer

:ride:


Yes the piston is stuck, but not for the reason you said. The piston is stuck b/c the auto-decompression mechanism on the cam stuck out, thus not releasing the pressure in the cylinder and not allowing you to turn the engine over (all as Gray said). I wouldn't get too cocky if I were you, Gray was just correcting your error.

  • clutchless

Posted July 29, 2008 - 08:12 PM

#13

Yes the piston is stuck, but not for the reason you said. The piston is stuck b/c the auto-decompression mechanism on the cam stuck out, thus not releasing the pressure in the cylinder and not allowing you to turn the engine over (all as Gray said). I wouldn't get too cocky if I were you, Gray was just correcting your error.


its still stuck, gray just explained in more detail. and i learned something.

and as gray know's racing D38 there are times you can't roll the bike back. for instance when accending or decending sand damn. the sand is to soft that kicking is your only way to get the bike started.

  • clutchless

Posted July 29, 2008 - 08:13 PM

#14

This guy has spheres of steel.
In the words of some Japanese military captain sometime in 1942 "Why would you wake a sleeping giant?"


gotta do something to liven this place up. i hear crickets chirping in this forum. not my fault our bikes don't break.

  • Justin89

Posted July 30, 2008 - 04:42 PM

#15

gotta do something to liven this place up. i hear crickets chirping in this forum. not my fault our bikes don't break.


I dunno...I go throught sprokets and rear tires like crazy :ride:





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