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 Valve Check on R² at 24,500 miles

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10Cup

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PostSubject: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 6:12 pm

my bike has 24,500 miles on it so I checked my valve clearance today, Yamaha recommends checking valves at 26,600 miles.

Both Exhausts were at .20mm (spec is .23-.30) so very tight!
Left intake was at .10mm (spec is .13-.20) again very tight!
Right intake was at .13mm just in spec.

So the Yamaha recommendation of 26,600 miles may be a bit long.

Just an FYI for all you out there riding on the wonderful little bike.

I have had zero problems with mine, it's an 09 and I change the oil and filter every 4,000 miles, fill it with gas, keep bearings greased and ride the heck out of it.

Later

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motokid
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PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 7:04 pm

Over time, is it typical for valve clearance to tighten up, or loosen up?

My pea brain common sense thought process would guess valve clearance would loosen up.
Things would get sloppier.


_________________
2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs
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zestymac

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PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 7:25 pm

My $.02

Depends on the wear points. The older Yamaha FZR engines that were raced would almost always tighten up clearances over time from valve seat wear or movement of the seat in the head. A cam over bucket can spread the friction over a much bigger area than a rocker arm over a valve stem.

Discuss... Very happy
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aaronhall555

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PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 7:27 pm

motokid wrote:
Over time, is it typical for valve clearance to tighten up, or loosen up?

My pea brain common sense thought process would guess valve clearance would loosen up.
Things would get sloppier.


I would think so too, but thinking about the mechanics of the valvetrain, the valve springs probably stretch the valve stems over time? IDK.
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KLRchickie




PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 7:29 pm

motokid wrote:
Over time, is it typical for valve clearance to tighten up, or loosen up?

My pea brain common sense thought process would guess valve clearance would loosen up.
Things would get sloppier.


I believe it is most common for this type of valve arrangement to have the clearances tighten over time. My rationale to explain it is that the force of the spring "slamming" the valve closed repeatedly pulls said valve further & further into the head, slowly moving it closer to the cam lobes.
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aaronhall555

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PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 7:29 pm

zestymac wrote:
over time from valve seat wear

...this too.
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KLRchickie




PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 7:30 pm

aaronhall555 wrote:


I would think so too, but thinking about the mechanics of the valvetrain, the valve springs probably stretch the valve stems over time? IDK.

Plastic deformation of the valve stem itself seems pretty unlikely to me (and darned scary too eeek ).
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zestymac

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PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 9:16 pm



"My rationale to explain it is that the force of the spring "slamming" the valve closed repeatedly pulls said valve further & further into the head, slowly moving it closer to the cam lobes."

I don't believe it's the valve stretching. When we went to harder valve seats on the FZR engines, the clearances lasted way longer.; and thses engines usually lived near redline. The OEM valve seats were probably a tad softer to give a better seal on a less than perfect fit in the normal manufacturing process.
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KLRchickie




PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 9:26 pm

zestymac wrote:


"My rationale to explain it is that the force of the spring "slamming" the valve closed repeatedly pulls said valve further & further into the head, slowly moving it closer to the cam lobes."

I don't believe it's the valve stretching. When we went to harder valve seats on the FZR engines, the clearances lasted way longer.; and thses engines usually lived near redline. The OEM valve seats were probably a tad softer to give a better seal on a less than perfect fit in the normal manufacturing process.

I didn't suggest it was valve stretching (I would find that pretty disturbing from a metallurgy point of view) - "pulls said valve further & further into the head" was meant to suggest head (valve seat) wear, not valve stem stretch.
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skierd




PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 9:30 pm

Interesting, good to know how tight your valves were especially given HF's findings on his bike during the Athena install.

http://www.advrider.com/forums/showpost.php?p=14071497&postcount=52

Quote :
Next, compare those measurements to the specified range listed in the Service Manual.....which is this:

Valve Clearance (cold)
Intake 0.13 - 0.20 mm
Exhaust 0.23 - 0.30 mm

And now.....drum roll.............................................. my measurements were (at approximately 8,000 miles):

Left Intake 0.13 mm
Right Intake 0.13 mm

Left Exhaust 0.23 mm
Right Exhaust 0.23 mm

I could force a 0.15 mm into only one of my Intake gaps, but decided it was much too tight to be correct. So, I accepted that both were 0.13 mm in clearance.
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millert85




PostSubject: Re: Valve Check on R² at 24,500 miles   Thu Oct 21, 2010 11:06 pm

clearances will tighten because the top of the valve erodes away from the constant hammering, making it sit further into the head. that makes the stem sit higher/closer to the cam.
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Dancamp




PostSubject: Re: Valve Check on R² at 24,500 miles   Fri Oct 22, 2010 6:33 am

Not knowing what were the original settings it's hard to know exactly how it goes. Unless we assume the settings were right in the middle out of the shop and I doubt of that.

Next time you'll check will tell more about how these valves wear.
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motokid
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PostSubject: Re: Valve Check on R² at 24,500 miles   Fri Oct 22, 2010 7:17 am

So the weak link is the valve seat?

When you check the valve clearance what gap are you actually measuring?
Where are you sticking the gage? Between what two surfaces?




_________________
2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs
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motokid
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PostSubject: Re: Valve Check on R² at 24,500 miles   Fri Oct 22, 2010 7:26 am

nevermind....I now understand why the "clearance" would get tighter over time.

I looked at the service manual and discovered what was going on.

Very happy


It is common sense - but you have to know where the measurement is taken.

I now know.


_________________
2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs
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