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Valve Clearance Check

StratTuner said:
Here in the People's Republic of Calif., there are only two seasons: HOT an Rainy.
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I live in northern Michigan. One minute it's sunny and warm, the next rainy / snowy and cold. When I leave work around 3am, it's been dipping down in the mid 30's. That's a bit cold for me, without dressing in snowmobile gear.
 
I checked the valves for the third time this evening after dinner. In no hurry at all it took less than two hours. In 7800 miles 1 exhaust valve had moved from .011" to .010" which is still in spec but I moved it back to .011". This job couldn't be easier to do for the average DIY owner.
 
dduelin said:
I checked the valves for the third time this evening after dinner. In no hurry at all it took less than two hours. In 7800 miles 1 exhaust valve had moved from .011" to .010" which is still in spec but I moved it back to .011". This job couldn't be easier to do for the average DIY owner.
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Dave, I did my valves for the first time at 8000 miles. Based on the minimal amount of adjustment needed, especially for the first check, I'm not planning to do the next check until 20K miles. How many miles are you at, and are you seeing such minimal changes needed that the interval could be safely expanded?
 
670cc said:
Dave, I did my valves for the first time at 8000 miles. Based on the minimal amount of adjustment needed, especially for the first check, I'm not planning to do the next check until 20K miles. How many miles are you at, and are you seeing such minimal changes needed that the interval could be safely expanded?
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I did the first around 7900 miles, the second at about 13500 miles (was getting ready for what I thought might be a 5000 mile trip), and this one at 21300 miles. No valve was out of spec and movement was limited to several moving .001" between checks. I think I'll stretch the interval to 12,000 miles next time but I have not left any one valve at minimum spec but instead moved minimum ones back to the middle of range.

To your point I'd do at least two checks before changing the interval. No two engines are identical or ridden in identical conditions of operation and I'd tell anyone not to think their engine will act like mine has.
 
It seems like most accounts that I hear agree that the valve specs generally wear closed (as opposed to open, which is generally more common in the automotive world). The only thing that I can think of that would cause valve gaps to wear closed would be the edge of the valves and the seats wearing into each other. This would bring the valves higher into the head and decrease valve gap at the stem tip. Any other component wearing (valve stems, rockers, or cam lobes) would wear the valve gap open. My guess is that the initial bedding of the valves-to-seats causes the decreasing gap, then it will stabilize for most of the life of the engine. As the engine gets very old, the gap might start to open up as the stems, rockers, and cam start to wear down.

This is just my guess. At any rate, for the majority of the engine's life, they will probably stabilize to a point where they won't require checking or adjustment for 40,000 miles.

TL;DR: I agree. Extend the valve check interval and enjoy the extra riding time.
 
Dave, Greg, et al; since the NC750X has now been determined to have an inspection/adjustment distance of 16,000 miles versus our 700's 8K, does anyone think the new engine with it's tweaking has allowed this, or is it possible the 700's are likely to have a real life similar expectation, and the 8K was very conservative?

Doubling the adjustment interval is quite the abrupt change in parameters with the method of actuation unchanged, and I can't really see what would account for such a radical update?
 
Different valve seats? Different treatment or coating of the valve stem ends? Those are two simple ways they _could_ have reduced wear (thus extending inspection intervals). Don't know, just possibilities.
 
Thanks for posting your valve adjustment for us all to view. I'll have to pick up the manual and try this myself. I used to adjust my BMWr80rt boxer once/year. This does look even easier. One question- does the valve cover gasket need replacing after you're done? Thanks again and safe and happy riding!
 
Jonathan Curran said:
Thanks for posting your valve adjustment for us all to view. I'll have to pick up the manual and try this myself. I used to adjust my BMWr80rt boxer once/year. This does look even easier. One question- does the valve cover gasket need replacing after you're done? Thanks again and safe and happy riding!
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Nope. The gasket is reusable.
 
Jonathan Curran said:
Thanks for posting your valve adjustment for us all to view. I'll have to pick up the manual and try this myself. I used to adjust my BMWr80rt boxer once/year. This does look even easier. One question- does the valve cover gasket need replacing after you're done? Thanks again and safe and happy riding!
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The service manual says to replace it every time but I haven't and don't plan to as long as it remains pliable and doesn't weep.

I had a R100 for many years. I checked the valves on it every 5,000 miles or so. The NC is slightly more difficult than an airhead only because the NC 's radiator has to be moved out of the way to access the tappets but the actual checking and adjusting are pretty much the same.
 
L.B.S. said:
Dave, Greg, et al; since the NC750X has now been determined to have an inspection/adjustment distance of 16,000 miles versus our 700's 8K, does anyone think the new engine with it's tweaking has allowed this, or is it possible the 700's are likely to have a real life similar expectation, and the 8K was very conservative?

Doubling the adjustment interval is quite the abrupt change in parameters with the method of actuation unchanged, and I can't really see what would account for such a radical update?
Click to expand...

I didn't have time for my second valve inspection until 18,250 miles. So 10,250 on this service. All but one was a little tight, so I'm going to keep my inspections at 8-10k miles until they don't need adjustment. ymmv
 
Just did the first valve adjustment (since I am off for Spring Break), and found most tightened up on me. I waited until just over 12k miles to do the first check. The bike has seen just one long trip from Florida to Michigan. I have ridden it mostly around the backroads other than that trip. I also did my wifes CTX700 at the same time, which has just over 11k miles. She has shadowed me everywhere, and her valves were pretty much within specification. Same motor, different bikes, different clearances.
 
I checked mine for the first time this weekend with 7,900 miles on the odometer, and I found 2 intakes to be at 0.15mm and 2 to be at 0.13mm. All exhausts were at 0.23mm. I loosened all 8 to 0.17mm/0.28mm. Start to finish was about 2.5 hours. BUT ... BIG BUT ... add another hour, because after a test ride I came back to find oil had blown out around the valve cover. I had failed to ensure that the gasket was seated properly around the entire cover, and up top around the intake it had fallen out of its channel as I was installing it. Don't repeat what I did, and press the gasket into its channel on the cover all the way around and be mindful placing it on the engine that it stays in place. ;-)

I'll repeat others sentiments that it's well worth the extra effort to remove the radiator. Gives you all the room in the world.

-Payne
 
Quick question... did you replace a the camshaft maintenance cap O ring (and the other two O rings)? I am having a hard time finding them on the OEM parts listing.

D
 
docb91b said:
Quick question... did you replace a the camshaft maintenance cap O ring (and the other two O rings)? I am having a hard time finding them on the OEM parts listing.

D
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The O-rings should be good for a long time. Only if accidentally cut or nicked, or if they swelled and got loose, would they need replacement.

Reinstall the old ones and move on.
 
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