Second Valve Clearance check at 32,000 and some shims needed.

[RCS]

I thought I'd skate through the second valve check at 32,000 miles without a change - I had to change one exhaust shim on the first check at 16,000. Well, I wasn't so lucky. 7 of my 8 exhaust valve clearances tightened up and two are out of spec now well the other 5 are right on the brink of being out of spec. One of my intake valve clearances tighten up too, but it is still in spec.

Why is this happening. I have no clue. I rarely rpm over 5,000. I do, however, travel at highway speeds for 11 hours straight for virtually 100% of my 32,000 miles and sometimes I follow a fast car on the highway now and then. Maybe it is prolonged heat that causes the valves to seat deeper in the cylinder head and thus tightening the valve clearances?

Regardless, the way I ride my ST-1300 I will be checking my valves every 16,000 miles until they (the valve clearances) stop tightening.

 

[dduelin]

I always thought that high rpm was the biggest factor in valve train wear. Go figure.

Did you use the same feeler gauges as before? Go no-go method?

 

[RCS]

Just finished. I used some Craftsman feeler gauges. It wasn't too difficult and I took a lot of breaks.

Interestingly, when I was done I put the bike in gear on the centerstand and heard some clanging sounds in the rear wheel or swingarm. I'm probably going to change the U-Joint since I have one in my bin-o-parts. But, I'll save that for another day since my riding season is over for the year.

 

[st1300doug]

I thought valves ]tighten, not loosen with time...wear????

 

[Blrfl]

7 of my 8 exhaust valve clearances tightened up and two are out of spec now well the other 5 are right on the brink of being out of spec.

So to put that another way, the outcome of your check was that six of the eight exhaust valves were in spec and two weren't. Unless some of your valves went from the loose end of in spec to the tight end, I wouldn't worry too much about it. Adjust the two that need it, button the bike up and enjoy the next 16,000 miles.

How much did the clearances change? Did you do your measurements with imperial or metric feelers?

Why is this happening.

It's probably uninsured mice. Or squirrels. Never mind... Wrong thread.

--Mark

 

[Tom Mac 04a]

I thought valves ]tighten, not loosen with time...wear????

The valves actually sit lower in the valve opening as they wear in.... tighting up the clearance . It's really not wearing much on the cam/top of valve/shim/bucket.

 

[RCS]

So to put that another way, the outcome of your check was that six of the eight exhaust valves were in spec and two weren't. Unless some of your valves went from the loose end of in spec to the tight end, I wouldn't worry too much about it. Adjust the two that need it, button the bike up and enjoy the next 16,000 miles.

How much did the clearances change? Did you do your measurements with imperial or metric feelers?

Exhaust valve clearances to/from (in metric) before yesterdays shim change.

.20/.23
.21/.27
.22/.23
.22/.23
.25/.26
.22/.25
.22/.26
.22/.26

 

[hoowasat]

The valves actually sit lower in the valve opening as they wear in.... tighting up the clearance. It's really not wearing much on the cam/top of valve/shim/bucket.

If there was any wear on the valve/shim/bucket end, the gap would increase. The ST1300 valve gaps decrease with wear. While the idea of the valve sitting lower in the valve opening as they wear in sounds plausible, I tend to believe there's more movement at the valve seat. Where the valve seat is positioned in the aluminum head provides the one "soft spot" in the valvetrain. The constant slamming shut of each valve, especially at any speed where the valve may "float" off the backside of the camshaft (when the cam is letting the valve close), has me wondering if the softer aluminum head is compressing slightly beneath the valve seat. Reinforcing this belief are many reports which have been posted indicating that after an initial shim adjustment, few if any changes are required later. Is that a result of the valves seats finally being seated in the aluminum ... and that the aluminum will compress no further?

It was those observations that drove me to delay my initial valve shim adjustment until 26K miles.

 

[okmurdog]

That one valve that changed by 0.06 does seem a bit odd -

When I checked the valves on mine at 16k & 32k, I observed one valve that tightened by 0.03 mm. Seven didn't change at all; seven changed by 0.01, and one changed by 0.02.

The one valve that changed by 0.03 went on to change another 0.01 by the time the 48k check rolled around (sending it out of tolerance).

Also...for good measure, I always run Seafoam thru at least one tankfull before the valve check - I think it helps to clear out any carbon deposits that may interfere with the check. I had some odd results on the very first valve check (some showed out of tolerance) - I buttoned it up, ran a tankful of seafoam (along with RPMs higher than I customarily run), and checked it again - all were within tolerance.