Advice needed on valve clearance measurements

[Dan_d_glassman]

I took a day off from riding to address some overdue maintenance tasks. In addition to oil and coolant changes, I performed the valve clearance check. I've got decent mechanical skills, but was still nervous with the extent that one has to dig into the engine to check the tolerances.

I can report that all parts disassembled and reassembled well. I did not have shims on hand to make adjustments, if needed, so I was hopeful that all would be in tolerance..... this is where I need some advise...

I took my measurements with a common angled leaf style set of feeler gauges. This presented my quandry - I have three exhaust and one intake that are questionable. What do you think based on the measurements?

Exhaust #4 left, #2 left and right [spec 0.25 +/- 0.03mm]
The 0.279mm gauge passes between bucket and lobe, but the 0.305mm will not pass. I have no other gauges to try between the 0.279mm and 0.305mm.

Intake #2 left [spec 0.16mm +/- 0.03mm]
The 0.178 gauge passes, but the 0.203mm will not. I have no other gauges to try between the 0.178mm and 0.203mm.


Unfortunately, the gap between these gauges does not tell me if the clearances are in spec or out. What are the potential consequences of these tolerances being too large?

I believe I will investigate getting my hands on the HOT CAMS shim kit that is being passed around and reset these back to nominal when convenient. Any reason for concern at this point?

 

[TPadden]

What are the potential consequences of these tolerances being too large?

A little bit of noise; probably not even noticeable. Personally I wouldn't worry about it.

 

[ST-DocLizard1]

I think that the clearances are either go or no go. I assume this is your first inspection and you did not state the mileage.

I just had mine inspected for the first time at 32K and they all were found to be within spec, but not necessarily in the middle of the range. Hence, no shims were changed.

Document your findings and inspect in 16K from now.

Better too loose than too tight.

"Slappy valves are happy valves."


Doc

 

[RaYzerman]

I personally wouldn't change them. You're on the right side of nominal and certainly nothing is very far off (less than .001"). A perfectionist would think differently and go to all the work of changing them but if it was me, I would be good.

 

[Dan_d_glassman]

Thanks for the comments. This is my first check on the bike and it is at 17,200 miles on a 2007. I believe I'll let them be if there is no harm in it. That would be one more day I can go ride.

 

[RCS]

The measurements look good. Mark them on a sheet of paper and use these measurements for reference at the next valve clearance inspection in 16,000 miles.

 

[MileHigh]

The measurements look good. Mark them on a sheet of paper and use these measurements for reference at the next valve clearance inspection in 16,000 miles.

+1

In the next 16K miles, pick up a HotShims kit so you will be ready.

Go ride.

 

[Scooter]

+1

In the next 16K miles, pick up a HotShims kit so you will be ready.

Go ride.

Your fine where you are. There is a reason why Honda gives you a tolerance range. I wouldn't even bother spending the money on a shim kit. Odds are very good that they won't change by the next measurement anyway and if they do they will likely move the other direction (i.e. tighter).

Just as Mark says... Go Ride!

 

[newbieinreno]

Scooter,,,why would they go tighter?...The reason I'm asking is my Honda XR600R was on a
long desert 3 day ride and after 160 miles she shut down,,no compression,,,had to push start...
turned around to nearest town(cantina) and called for the truck,,when I stripped her down,,
1 intake and 1 exhaust were almost zero gap!....does the lock nut vibrate loose and then tighten
on their own???...I to would have thought looser over time....

Thanks :bow1:

 

[BigTom]

Different set up. Your XR had an adjustable tapett pushrod set, the ST is a direct follower shim system.

On the ST, as the follower wears the valves get tighter.

Edit: I lied. The XR doesn't have pushrods, but the cam followers are over the top with adjustable valves (sometimes STILL called a tapett)

 

[RaYzerman]

On the ST, as the follower wears the valves get tighter.

I always thought it was because the valve seats wear and they get closer to the follower. If the shims, cams or follower wear, wouldn't the clearances get larger? And I think it is more likely the valve seat wear, although very slow over time, is more likely than the shim/follower wear since they are always slathered in oil.

 

[TimM]

Carbon builds up faster than seats wear... according to Honda.

Question: Just did a valve clearance check - 16k miles, bike was probably warmer than cooler and was ridden earlier in the day. All exhausts came in at 10 or 11. Many intakes came in at 6, a couple at 7, one probably at 8. I say probably an 8 because I have a tendency to force the gauge in... how hard do you push when you have to bend the feeler to get it into the space anyway?

So my question: the 11 is on #2, and the 8 on #4, both right side, and both middle of the rack. The 11 is in spec, but the 8 is +1 out (good side of out). Should I fix it or do I watch it and fix it at 32k if it needs it?

6=0.006", 7, 8, 10, 11 ditto.

 

[Old2wheeler]

TimM: You should be fine, but they should be checked cold. If I were you I'd re-check if I hadn't put it all back together. Depends on how "not cold" it was. Don't push hard to force the gauge in. It should slide through snugly though.

My bike had many tight exhausts needing shims at 64,000. So, my experience is that they get tighter due to seat wear. If they get too tight they will burn.

Dan: Highly recommend a Craftsman 40804 bent imperial gauge set. It is almost impossible to get all the metrics you would need. The imperial gives slightly tighter tolerances (actually I think intake's max, or .007inch, is perhaps slightly looser than metric.) But the point is that Honda giving us specs in inches is not letting us do anything that will damage the engine. The Craftsman checked out extremely accurate on the micrometer and the bend helps (also the bend won't let TimM push too hard!) Only cost around $10.

Like RCS said keep a record of them.

Rod

 

[Scooter]

If you're only off .001" from the suggested tolerance value I would have no problem leaving it go until the next measurement at 32K especially since you are on the loose side. I wouldn't be surprised if it doesn't move at all by then either.

One thing to consider, If you are forcing that feeler gauge in there you probably are not as loose as you might think. It shouldn't take much force to get the feeler between the shim and cam lobe.

 

[TimM]

Well, next morning and the 0.008" feeler would not go under the cam... also checked some of the 0.006" gaps and they remained 0.006". Perhaps marginally tighter, but not 0.005". Perhaps the center of the right cylinder head - where the two loosest reading were - takes longer to cool down.

As far as "force" goes, I don't have an angled gauge set, so have to apply pressure to the gauge to get it into the tight spots. The learning here is to use a more suitable gauge next time.