My yamaha just stopped, Help?=)

i was driving my yamaha wr 450 2003, when it just stopped on the middel of the road, i culdent use the kick to start it, it normaly only takes one or two kicks to get it startet, my friend pulled my bike and i got it startet.

but there was no "power" in the bike, and a strange sound.

the engiene stops if the bike is not moving, i have changed the sparkplugs.

any idea whats wrong? :\

Valves/cam chain. Time for a top end

ok, thanx, but what do you mean with time for a top end? not that good in english :worthy:

From what I can read, it sounds like you have a valve realted failure. "Top End" is the top part of your engine (cylinder and head).

so maby i just have to adjust the valves? it have just been on service and was working great, and sudenly this happens...

Cant it be a sheared flywheel woodruff key?

its not a sheared flywheel woodruff key:\ have checked.. can the valves just jump out off position? the bike just had a full service... im going to check the valves this week... have been on vacation and now i want to ride my bike! :worthy:

My bike had same symptoms. Pulled the valve cover off tonight and found timing chain is stretched and jumps across cams. Causing everything to be out of sync. Chain Tensioner was fully extended time for a new chain. Maybe the dealer (service people) forgot to adjust yours properly or something.

i also opened and took a look, but the chain looked okey for me, maby i have to check one more time. but it seems to be the valves that are out of position, they shuld stand in a "system" position right? can the valves just jump out of position, i tought that was somthing that happend over time... thanx for answer=)

Unless you are familiar with what you are looking at when you remove the valve cover, you won't see any 'problems'. As William said, it's probably a worn out top end that needs replacing: Valves, seats, guides, cam chain and tensioner.

You have not told us the hours/miles on the motor, or anything about service intervals, so we assume it has been 'run till it drops' more or less.

you have to put the engince at TDC (Top Dead Center) meaning piston is up.

Your make on the flywheel should indicate this, the valve lobes should be pointing to the outsides more or less and the outside dots on the cam gears should be level with the top of the head - this confirms that your cams have not jumped time.

Next, check your valve lash clearance with the appropriate feelers.

Download your manual if you do not have one from yamaha of Australia.

i checked the valves and they where out of position with no clearence, and we adjusted them right, we tought that we had found the problem but, when i got my bike together and tryed to start it the engiene was the same, wont start and just backfires every 20 kickdown or somthing.. :thumbsup:

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