Valve Gaps - whats normal?


15 replies to this topic
  • thedktor

Posted June 10, 2008 - 06:59 AM

#1

.
So, on a brand new 2006 model, I have now put in about 5 hours use and checked the valves for the first time.

Intake nicely in spec.

Exhaust the spec is .2 - .25mm and they are a snug fit on a .2mm and definitely wont take a .25 feeler.

So, should I worry or will a bit of cam/shim wear counter-act any further bedding in of the valve seat? Or will they just not move for a while?

Thanks

TD

  • grayracer513

Posted June 10, 2008 - 10:20 AM

#2

The way to tell is to check them again at another 5-10 hours. For now, they are OK, and were very likely built just as you found them. Normally, the valve clearance will stay at one point for hundreds of hours without adjustment.

  • matt4x4

Posted June 10, 2008 - 11:43 AM

#3

As Gray said - and that's exactly why people destroy heads.
you check every 5-10 hours over and over and nothing ever changes - sooner or later, you will stop checking your valves - human nature dictates this.
When you stop checking your valves - you WILL destroy your engine - Murphy's law dictates this.

Moral here is always always always check your valve clearances.

  • RocketScientist

Posted June 10, 2008 - 08:15 PM

#4

When you stop checking your valves - you WILL destroy your engine - Murphy's law dictates this.


I take it that you are missing a hand or leg from a catastrophic engine explosion from your worn valves. LOL.

Sorry, couldn't help myself.

  • thedktor

Posted June 10, 2008 - 11:41 PM

#5

OK, I will check them again after a few rides, and hopefully I will be reassured.

Thanks

TD

  • matt4x4

Posted June 11, 2008 - 04:21 AM

#6

No, I just know this will happen because it happens to everyone on TT that DOESN'T check their valves regularly - (see Honda forum).

  • grayracer513

Posted June 11, 2008 - 06:18 AM

#7

That's the Honda forum. The first negative result of not checking YZ valves frequently enough is usually hard starting cold, and/or a hanging idle, both of which can result from insufficient intake valve clearance. The danger with YZF's is in running any valve that has needed shimming .10mm or more smaller than its original shim for any length of time. Such valves are at risk of breaking the stem off, which can do a lot more than ruin a head.

While it never hurts to check, YZF's are not Hondas, and don't have the same issues.

  • matt4x4

Posted June 11, 2008 - 06:52 AM

#8

What I'm trying to say is YZ/WR -F's have this tendency to make owners get lazy with continuing to perform the preventative maintenance due to valves never moving, never needing shims, this gives a false sense of security that all is well, as soon as the nitride wears the valves will wear down quite fast, it's at this point your diligence (if you've kept it) pays off.

For honda owners it's a little different, since they just have this false sense of security that seems to come with every to bill of sale "It's a Honda, it'll last forever", so, they don't even bother checking valves.

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  • grayracer513

Posted June 11, 2008 - 07:47 AM

#9

In either case, no destruction, explosions, or loud noises are apt to occur from not checking valves, and longevity is not improved by allowing fresh air under the cam cover without doing anything else to the engine. It is unarguably more prudent to check often enough to see the first signs of wear, but if this is not done, symptoms of poor performance will show up well ahead of any disaster. So, even though regular inspection is advisable, there isn't much reason to loose sleep over procrastinating a little.

  • m1ke234

Posted June 11, 2008 - 08:37 AM

#10

Gray,

Thanks for the advise.
I just bought a 98 WR400F from the original owner.
He said besides for the first checkup the motor has not "been into".(I guess that means no valve checking):thumbsup:

He also said it is a low hour bike, I cant tell because he took the odometer off for a speedo. but the chassis seems like it.

I have changed the oil,filter, fuel lines(they were shrinking), cleaned out the old gas, spark plug, and lubed everything.
It starts first kick hot or cold and runs great.

I have been "losing sleep" over checking these valves in fear I was going to blow the engine.

I will check them before I bring it out for a real days riding.

I took it out for a test drive last night and I thought I may have heard some valve noise. I have worked on plenty of engines, but not these. Its not a bad noise like a knock, it sounds more like a lifter noise(in a car) or something

At low RPMs if I load the engine in a higher gear(4th,5th) is when I hear it. But it clears up as the rpms go up.
If I ride in higher rpms It doesnt make it.

I have also read forums on here that said these engines are just noisy.
Is this normal noise?
should I try not to drive this bike in the low RPM range at higher speeds?

-thanks

  • matt4x4

Posted June 11, 2008 - 08:48 AM

#11

First - your bike has ss valves, which tend to hold up better than ti valves.
Second - yes, they are noisy by nature.
You're likely hearing the cam chain, drivetrain, more noticeable at lower rpms.
You CAn ride these things at low rpm's without worry - they actually pull pretty good when you give it an extra gear - sometimes it actually works to your advantage.

  • m1ke234

Posted June 11, 2008 - 11:02 AM

#12

Thanks for the help.

  • grayracer513

Posted June 11, 2008 - 12:12 PM

#13

As said, it sounds like you are describing rear chain slap, which results from the wide separation of power impulses at low speeds in combination with th every low rotating mass of the YZF engines. That would be normal.

In general, you will hear a variety of noises from a healthy YZF, including timing chain and valve train rattles, mostly at idle, primary gear backlash and transmission "growling", again, at idle, and occasionally, a little piston slap.

One noise to be wary of is a rattling connected to the engine speed that resembles a rod bearing noise. This can happen if the crank primary gear bolt loosens and allows the balancer gear to rattle on the key that drives it. This must be fixed ASAP if it turns up, since letting it go will result in a damaged crank axle.

Your engine does have steel valves. I don't agree that they hold up better, but they do wear differently than Ti. Titanium YZ valves will resist any detectable wear for an unbelievably long time, then finally wear through the hard coating and be thereafter unable to hold a clearance adjustment for even a few hours. Stainless, particularly the way Yamaha does it, also lasts a very long time, but the hardening is done by processing the metal, so it is deeper than on Ti valves. If you have to shim a Ti valve .05mm smaller, it is not uncommon to have to reshim again in a few hours, meaning the valve is no longer usable. A Stainless valve may need shimming a little sooner (maybe not), but also may hold up fine after being shimmed down as much as .10mm for quite a while longer.

  • m1ke234

Posted June 11, 2008 - 03:37 PM

#14

Thanks again guys

I dont think it is the drive chain slap Im hearing. I was driving at constant speed on the road when I heard it.
But it does sound like it could be a slap.
I usually have a good ear for engine noise.
It may be the little piston slap you mentioned, my dad's Harley has a piston slap but his noise never really goes away, the noise I heard was inconsistant and went away with higher rpm's.

At idle the engine sounds really healthy.

As for the crank primary gear loosening that sounds like it would be a nightmare.:thumbsup:
That noise wouldn't be a noise that comes and goes would it?
I would think a noise like that would be constant and get worst with higher rpms.

Thanks again for your guys knowledge.

  • swede426

Posted June 11, 2008 - 04:09 PM

#15

Gray,

Thanks for the advise.
I just bought a 98 WR400F from the original owner.
He said besides for the first checkup the motor has not "been into".(I guess that means no valve checking):thumbsup:

He also said it is a low hour bike, I cant tell because he took the odometer off for a speedo. but the chassis seems like it.

I have changed the oil,filter, fuel lines(they were shrinking), cleaned out the old gas, spark plug, and lubed everything.
It starts first kick hot or cold and runs great.

I have been "losing sleep" over checking these valves in fear I was going to blow the engine.

I will check them before I bring it out for a real days riding.

I took it out for a test drive last night and I thought I may have heard some valve noise. I have worked on plenty of engines, but not these. Its not a bad noise like a knock, it sounds more like a lifter noise(in a car) or something

At low RPMs if I load the engine in a higher gear(4th,5th) is when I hear it. But it clears up as the rpms go up.
If I ride in higher rpms It doesnt make it.

I have also read forums on here that said these engines are just noisy.
Is this normal noise?
should I try not to drive this bike in the low RPM range at higher speeds?

-thanks


These engines does'nt like low rpm:s combined with hig gears and it's most likely chain clatter (not cam chain) so yes, this noise is normal during the circumstances you mentioned.

  • grayracer513

Posted June 11, 2008 - 10:09 PM

#16

Thanks again guys

I dont think it is the drive chain slap Im hearing. I was driving at constant speed on the road when I heard it.
But it does sound like it could be a slap.
I usually have a good ear for engine noise.
It may be the little piston slap you mentioned, my dad's Harley has a piston slap but his noise never really goes away, the noise I heard was inconsistant and went away with higher rpm's.

At idle the engine sounds really healthy.

As for the crank primary gear loosening that sounds like it would be a nightmare.:thumbsup:
That noise wouldn't be a noise that comes and goes would it?
I would think a noise like that would be constant and get worst with higher rpms.

Thanks again for your guys knowledge.

The balancer key noise would be speed sensitive, and diminish as the rpm increased, buy it would NOT be load sensitve, and it would be there regardless of load.

Chain slap would be present only under a load, underway, and at low rpm.




 
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