07 yz450 valve lash help


10 replies to this topic
  • danimal95

Posted March 20, 2011 - 04:20 PM

#1

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a few weeks back i high sided and broke my collar bone,the bike was running on its side for afew minutes before a friend was able to kill the motor,that being said....my bike always seemed mechanicaly loud too me but after the crash (2 weeks later)i threw my leg over it again for the 1st time since the wreck and when i startde it i noticed a dulll tap,(i would compare it to a lifter or rocker arm tap in a car engine) but it was only present at idle and the worst part is,is that i dont recall if it was always there or if im just being paranoid about it running on its side.in any event i decided to do some checking into it before it tuned into a big problem.

i brought it home and started doing some research,alot of people online were saying that noise is common in these engines but more often than not it is a stertched timing chain and worn tensioned,so those being cheap parts i just ordered them figuring that it was apart may as well change them.so after tearing it down i decided to check the valve lash,the exhaust side was right in spec accordin to the yami manuel,the intakes however were different,only 1 was within spec and the other 2 were too tight,is this common?essentially it is hanging open 2 of the intake valves,it is as simple as re-shimming or do i have other issues going on?thanks in advance

  • grayracer513

Posted March 20, 2011 - 09:32 PM

#2

How tight is too tight?

  • skull1971

Posted March 21, 2011 - 03:44 AM

#3

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a few weeks back i high sided and broke my collar bone,the bike was running on its side for afew minutes before a friend was able to kill the motor,that being said....my bike always seemed mechanicaly loud too me but after the crash (2 weeks later)i threw my leg over it again for the 1st time since the wreck and when i startde it i noticed a dulll tap,(i would compare it to a lifter or rocker arm tap in a car engine) but it was only present at idle and the worst part is,is that i dont recall if it was always there or if im just being paranoid about it running on its side.in any event i decided to do some checking into it before it tuned into a big problem.

i brought it home and started doing some research,alot of people online were saying that noise is common in these engines but more often than not it is a stertched timing chain and worn tensioned,so those being cheap parts i just ordered them figuring that it was apart may as well change them.so after tearing it down i decided to check the valve lash,the exhaust side was right in spec accordin to the yami manuel,the intakes however were different,only 1 was within spec and the other 2 were too tight,is this common?essentially it is hanging open 2 of the intake valves,it is as simple as re-shimming or do i have other issues going on?thanks in advance


Check the oil filter for metal in the oil!!! my 2008 did the same thing, ran on its side, and it burned the bottom rod bearing. The rod knock did sound like it was in the top end, but it wasn't. When we pulled the old crank apart the bottom needles were trashed so bad the cage was rubbing on the rod, and it still ran!!

  • danimal95

Posted March 21, 2011 - 06:52 AM

#4

Check the oil filter for metal in the oil!!! my 2008 did the same thing, ran on its side, and it burned the bottom rod bearing. The rod knock did sound like it was in the top end, but it wasn't. When we pulled the old crank apart the bottom needles were trashed so bad the cage was rubbing on the rod, and it still ran!!


they measured about .030 too tight,and i dont think it is in the bottom already changed and inspected the oil and filter looked good..how noisy are these things?i may just be paranoid

  • grayracer513

Posted March 21, 2011 - 06:59 AM

#5

.030 of what unit? Metric or English? Since the intake are supposed to be set between .004-.006", how were you able to determine that they were .030" too tight?

Or, did you mean to say, .30mm too tight, in which case I still want to know how you arrived at that, since they start out between .10-.15mm.

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  • danimal95

Posted March 21, 2011 - 09:03 AM

#6

.030 of what unit? Metric or English? Since the intake are supposed to be set between .004-.006", how were you able to determine that they were .030" too tight?

Or, did you mean to say, .30mm too tight, in which case I still want to know how you arrived at that, since they start out between .10-.15mm.


sorry i did mean too say mm,i arrived at that by subtracting the measured amount of lash .70mm to the proper amount .10+/-mm

  • grayracer513

Posted March 21, 2011 - 11:39 AM

#7

Now you have said that you measured .70 mm of lash. Do you mean .07mm?

  • danimal95

Posted March 21, 2011 - 06:52 PM

#8

Now you have said that you measured .70 mm of lash. Do you mean .07mm?


Yes sorry I'm use to dealing in thousanths

  • grayracer513

Posted March 21, 2011 - 08:09 PM

#9

So since you're used to that, your .07mm is .003" instead of the .004" (.10mm) minimum specified. You will correct that with a .05mm (.002") smaller shim, and not worry any more about it until it goes below .004" again, if it does that while you own the bike.

Feel better?

  • danimal95

Posted March 22, 2011 - 11:33 AM

#10

So since you're used to that, your .07mm is .003" instead of the .004" (.10mm) minimum specified. You will correct that with a .05mm (.002") smaller shim, and not worry any more about it until it goes below .004" again, if it does that while you own the bike.

Feel better?


yep thanks,just wanted to make sure my thought process was right before i ordered the shims

  • grayracer513

Posted March 22, 2011 - 01:30 PM

#11

You may also very well run into a situation where you currently have an odd size shim in the bike, as the factory uses shims in increments of .01mm to set the engines up, and these are not available as service parts.

So let's say that you have one valve at .07mm and that it currently has a 187 shim in it (that means the shim is 1.87mm thick). If you buy a 185, that will result in a clearance of .09; not enough. But a 180 bumps it to .14mm. Now, that's still in spec, of course, and you remember that we said that .05mm is only .002", so it's really no big deal if the valve is set to the loose side of the specification. But if you do want to worry about that and get it closer to .10mm, look at the shim under the other bucket first, as you may be able to use that one, OR, order a half sized shim from Honda (for a CRF450). They sell increments of .25mm, and you would buy a 182 in this case (they round the markings off).





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