06 450 timing jumped???


11 replies to this topic
  • rodgemx125

Posted January 28, 2007 - 01:33 AM

#1

just done valve clearances on my yzf. when starting up it ran for a while then made a noise and stoped, cam chain had come loose and jumped round on the exhaust cam. i took the tensioner out and couldnt really see a problem with it so put it all back together. after running it again for a short period it slipped again but the chain was still tight?
anyone had anything like this before?

  • gord955

Posted January 28, 2007 - 05:24 AM

#2

Did you remove the head? Timing chain guides could be worn or out of place. It it sounds like the crank gear could be badly worn for it to skip. You should be able to see it from the top with a flashlight. It's possible also for the cam tensioner to be loose, I usually screw the tensioner in as tight as possible, when you release the tensioner turn it for a couple more turns to lock it secure. If the crank gear looks good, replace the timing chain, there cheap.

Good Luck

  • rodgemx125

Posted January 28, 2007 - 05:55 AM

#3

just been looking at the head again, all guides look fine and the crankshaft sprocket looks fine. but i put the exhaust cam in and bolted it up and its gone tight, you cant turn it round by hand at all and there was signs of it being tight to. both the dowls and locating ring on the bearing are in properley but its still tight???

  • mxracer206

Posted January 28, 2007 - 06:07 AM

#4

If you pulled the cams for any reason then it is easy to over-torque the cam holder. This is definately where you need a torque wrench and tighten to spec as you will almost always get them to tight without one. If you did not run it long you may be able to polish up the journals and save the head.

  • grayracer513

Posted January 28, 2007 - 09:02 AM

#5

If you pulled the cams for any reason then it is easy to over-torque the cam holder. This is definately where you need a torque wrench and tighten to spec as you will almost always get them to tight without one. If you did not run it long you may be able to polish up the journals and save the head.

This is where your problem lies. It sounds like you either over torqued the cam caps, torqued the out of sequence, or did not have the caps squarely seated when you torqued them. They are quite sensitive to such things, and in fact, I use a torque value of 75 in/lb (6.2 ft/lb) in place of the 86 (7.2 ft/lb) the manual calls for.

Unfortunately, the correction for this is going to be to remove the head and get the cam bores repaired. EDCo in California does a great job of this for a reasonable price.

You should also replace the cam chain, and carefully inspect the rear guide and the tensioner.

  • rodgemx125

Posted January 28, 2007 - 09:45 AM

#6

how do you think would be the best way to polish them up?

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  • grayracer513

Posted January 28, 2007 - 09:54 AM

#7

The cam bore is now out of round, and only a qualified machinist can repair that. They will need your cams and your complete cylinder head to correct the problem.

  • rodgemx125

Posted January 28, 2007 - 01:14 PM

#8

thanks, of to my mate in the engineering workshop tomorow then!
10nm doesnt seem very tight, do you use locktite or anything like that?

  • grayracer513

Posted January 28, 2007 - 04:42 PM

#9

thanks, of to my mate in the engineering workshop tomorow then!
10nm doesnt seem very tight, do you use locktite or anything like that?

No, and 10nM is not only the torque called for, I believe it is too tight.

The manual clearly calls for oiling the threads and torquing them to 7.2 ft/lb. This should be done in three successively tighter steps, and in an outward from center pattern on the intake, and in a circular pattern on the exhaust. As I say, I have been using 75 in/lb (6.2 ft/lb or 8.5 nM) for 3 years with no problems.

  • stock510

Posted January 28, 2007 - 05:00 PM

#10

Just did a valve adjustment the other day and made sure to torque them as specified.

Funny enough purchased the latest moto magazine and it had a write up on valves and it said the biggest mistake backyard mechanics make is overtightening the cam caps.

Hope it all works out for you.

  • grayracer513

Posted January 28, 2007 - 06:33 PM

#11

... the latest moto magazine ...said the biggest mistake backyard mechanics make is overtightening the cam caps.

And they're right.

  • rexbond007

Posted January 28, 2007 - 06:59 PM

#12

Just did a valve adjustment the other day and made sure to torque them as specified.

Funny enough purchased the latest moto magazine and it had a write up on valves and it said the biggest mistake backyard mechanics make is overtightening the cam caps.

Hope it all works out for you.


i did that to my 01 WR 250 i had tighten the cam caps so much that the bike would not idle on it's own, the motor just died.!!!!

lucky a thumper member in the 250 forum figured it out for me, before i did any damage.





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