Valve Adjustment Tolerances - How Far Do You Go?

[dave]

This question may be more applicable to those of you who perform your own valve adjustments, especially if your like me, and not real quick at performing a repair that you have either never performed before, of maybe haven't performed in several years:

My bike has 32,000 miles, and while I have inspected the valve clearances once, they were all in spec, and I have never performed an adjustment. I plan to go to 50,000 miles before I perform my next valve clearance inspection.

The specification for our valve clearances are: Intake = .006 +/- .001, Exhaust = .011 +/- .001. How far out-of-spec are you willing to allow your valves to get before you perform an adjustment? It's a significant amount of work just to inspect the valve clearances on these bikes, but the labor probably triples, or more, if you actually have to remove the cams to perform an adjustment. I'm thinking about letting my valves exceed the maximum tolerance by .001 before I actually perform an adjustment. To clarify, if my intake valve measured .004 (.001 below the minimum recommended clearance of .005) I'll let it go. If it goes to .003, then I will definitely adjust it. What do you think? Am I risking engine damage by allowing the valve clearance to go .001 inch below the recommended minimum clearance? Some members of this forum have stated that they don't plan to ever adjust the valves on their bikes, but I definitely don't support this reasoning.

I have been deliberately adjusting the valves on my Toyota truck .002 tighter than the nominal specification for the past 200,000 miles with no issues, but that's a different story.

 

[The Gecko_imp]

Have been talking to my dealer / mechanic because I am closing in on 12,000 miles end of the year. My manual says it's time for the first check (which I will do myself). She looked it up in her computer, and said my manual was wrong (outdated I guess this means), the first check was now at 15,000. Seems to indicate to me that the Honda maintenance department was more conservative in the beginning, and is now slowly extending the "distance".

How about the following approach. Check the first time at 15,000 (as you did, Dave). If it needed adjustment do it "by the book". If it was within spec skip the next control. Does this make sense ? It's somewhat between many checks (by the book) and no checks as you mentioned.

 

[GoldOxide_imp]

Regarding inspection, if you have service do it, ensure to ask whether they will perform a visual hands-on procedure, or a hands-off sound-based inspection.

Curious Forum minds might wish to know.

 

[The Gecko_imp]

Not always true. If the valve does no longer fit properly in its seat, e.g for burned products which do not belong there, the clearance will get bigger, not tighter.

Regarding inspection, if you have service do it, ensure to ask whether they will perform a visual hands-on procedure, or a hands-off sound-based inspection.

Curious Forum minds might wish to know.

Hi GO, is there a sound based, “reliable” sound based inspection method ?

 

[GoldOxide_imp]

Not always true. If the valve does no longer fit properly in its seat, e.g for burned products which do not belong there, the clearance will get bigger, not tighter.

Regarding inspection, if you have service do it, ensure to ask whether they will perform a visual hands-on procedure, or a hands-off sound-based inspection.

Curious Forum minds might wish to know.

Hi GO, is there a sound based, “reliable” sound based inspection method ?

Apparently, according to other forums. I have never seen it done on a motorcycle. Smoke and mirrors? Perhaps. Or coveted dealership craft?

 

[dave]

I'm surprised that not a single person had a response to my question. With all of you out there who spin your own wrenches not one of you care to share your opinion?

 

[mattmcuomo@yahoo.com]

I'm surprised that not a single person had a response to my question. With all of you out there who spin your own wrenches not one of you care to share your opinion?

I've got over 130,000 miles on my 14. I've never even checked the valves.

Sent from my Pixel 6 using Tapatalk

 

[Gone in 60]

I'll admit that while I adjust valves per schedule on my other bikes, on this one, I'm taking the "It's a Honda, I'm sure it'll be fine" approach.
And, on all other Hondas that I've owned and checked valves on, can't remember needing to make an adjustment.

 

[PowerDubs_imp]

keep in mind, valve clearances will typically tighten up as they wear, not get looser. i always aim for the looser end of the spec.

Absolutely.

Tighter is worse than looser.


As for the original question- the limits are limits for a reason.

Asking any of us if it is 'safe' is pointless.

Adjusting your truck tighter than spec is out of spec.

Again- tighter is worse than loose.

So- just like the guys that never check em- it's at your own risk, your mileage may vary.

 

[GoldOxide_imp]

I'll admit that while I adjust valves per schedule on my other bikes, on this one, I'm taking the "It's a Honda, I'm sure it'll be fine" approach.
And, on all other Hondas that I've owned and checked valves on, can't remember needing to make an adjustment.

All my Honda and Yamaha inline-4s never had the valve clearances checked. I tried once, but the dealership said it was not needed (non-hydraulic lifters). They did say they would do it and I would pay, but they were pretty confident it wasn't needed. I felt differently, even though the bike ran well.

The dealership also warned that some garages say the work was done on some jobs, but it wasn't.

As with many things with vehicles, it is best to just learn to do it yourself.

 

[Cormanus]

I just looked at your question again, Dave. Unlike others here, I'm not expert, but, as Dubs said, there are specs for a reason. If it's in spec — that is, within the tolerance — I'd leave it. If it wasn't, no matter by how much, I'd adjust it.

 

[dave]

Thank you for all the answers guys! That's the exact feedback that I was hoping for.

To reply to the question about why not adjust a valve if it was out of spec: It's a heck of a lot of work to adjust the valves on these bikes. After checking the clearances, I estimate it would take me probably an additional four hours to pull the cams, measure the existing shim, determine what replacement shim I needed, and then put everything back together, and this doesn't include the time to drive to the dealer to purchase the new shim. I am sure that Honda designed these engines with some factor of safety concerning the valve clearances, meaning these engines could probably run perfectly fine with the clearances at half of what the factory recommends without causing any issues. There are a lot of very skilled and experienced people who post to this forum who have a whole lot more experience than I do, and I was curious what their opinions were if I was to continue riding my bike with one, or more, of the valves just slightly (.001 inch) out of specification.

Again, thank you for your answers.

 

[GoldOxide_imp]

Indeed. There is enough labour involved just to check the clearances.

But, and as with anything in the material world, 'tis the price of piece-of-mind.

 

[Tev62]

Don't forget that minimum clearance is on a cold engine. That might be closer still on a hot engine depending on the design.

 

[The Gecko_imp]

Don't forget that minimum clearance is on a cold engine. That might be closer still on a hot engine depending on the design.

Very good point !