Whats wrong with my 06 yz 450 f

11 replies to this topic
  • richbar_1

Posted May 04, 2013 - 10:40 PM


Can anyone tell me how to fix my 06 yz 450 f. Kickstarter jams up?
But when you pull the sparkplug it kicks fine,and has compression.
Help please!!!! It does have auto-decompression.And hot start lever.
I do not have the manuel for it.

Edited by richbar_1, May 04, 2013 - 11:57 PM.

  • timmyp8823

Posted May 04, 2013 - 10:53 PM


Can anyone tell me how to fix my 06 yz 450 f. Kickstarter jams up?
But when you pull the sparkplug it kicks fine,and has compression.
Help please!!!!

It has compression when you pull the spark plug? You should fix it by taking it to a qualified mechanic. But seriously,did they have auto decompression in 06?Perhaps that is not working correctly. I haven't owned one since my 98 WR,and it only had a manual release. If yours has a manual release as well,learn the starting drill and give it a man kick.

  • wweagleflyer

Posted May 05, 2013 - 05:10 AM


The 06 YZ 450F does have an auto decompression. I would suggest taking off the valve cover to check your valve timing, and inspect the auto decompression while you are at it. You should see a push rod protruding from the magneto side of the exhaust cam lobe. You may have to use a small mirror to see in there though.

  • trandyd

Posted May 05, 2013 - 05:37 AM


My 06 would also jam on the top of the compression stroke if the kickstart was at the very top of its stroke. I always felt it was a combination of being at the part of the stroke with the most compression and the kickstarter not being able to move down far enough for the auto comp to work. My Valves and timing were correct.
It only happened every once in a while so I never really dove into why. Easiest way around it was to put bike into gear and roll backwards about a foot or just enough to get it out of the compression stroke.
That always did the trick.

  • richbar_1

Posted May 06, 2013 - 04:28 PM


My 06 yz 450 f jumped timeing. Stretched timing chain.Does any one know if you should replace
tensioner and slides when replacing chain ??????

  • wweagleflyer

Posted May 06, 2013 - 04:52 PM


I recently replaced my cam chain without replacing either the tensioner or the guides. If the tensioner is working properly, and the guides aren't excessively worn (mine were not) I don't think there is good reason to change them. I also checked with the local shop, and they said they almost never have to replace the cam chain guides. It is amazing how little they wear given what they go through.

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  • richbar_1

Posted May 06, 2013 - 09:36 PM


Hey thanks for the info. I bought the bike not running, for pretty cheap. Set the timing and it fired wright up ran for a few
Shut it off and it jumped again.Do you have to pull the jug?? I know you have to pull the side cover. So im going to take it
back down,put a chain in it. All gears look good.And the tensioner seems to be woorking ok.
Thanks again!!!!

  • grayracer513

Posted May 07, 2013 - 06:31 AM



  • NitrousR1

Posted May 11, 2013 - 06:14 AM


Its pretty rare to need timing chain guides or tensioners with these YZ450's. I've done about 30 rebuilds on these and only put on 2 new tensioners- when the owner wanted to replace them because of high hours. The guides you visually check for wear and the tensioner make sure you have good spring pressure and check for smooth operation.

  • mpmoto

Posted May 11, 2013 - 06:26 AM


how often does it do it ?

make sure the valve clearance on the exhaust cam is right. I'd run it at the low end of the spec, even slightly under on the decomp valve.

if the clearance is too big the auto decomp wOnt open the valve enough

  • mpmoto

Posted May 11, 2013 - 06:28 AM


^^^^ 0.10-0.15mm on inlets and 0.15-0.20 on the exhaust. set the ex right on 0.15 no bigger.

  • grayracer513

Posted May 11, 2013 - 09:27 AM



Exhaust valve clearance is .20-.25mm NOT 1.5 - .20 Don't ever set them tighter than .20mm

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