[RoelS]

Last year, just before the riding season started, my buddy and I did some maintenance on my 1100 EVO. He checked the valves, and they were well enough within spec for the upcoming season but they would require some attention after the season.
The clearances (in mm) were:
Horizontal
Intake: opener 0,15 - closer 0,05
Exhaust: opener 0,12 - closer 0,04

Vertical
Intake: opener 0,2 - closer 0,05
Exhaust: opener 0,13 - closer 0,1

I rode about 4500 km last year, and today I checked the valves again. Today's values are:

Horizontal
Intake: opener 0,13 - closer 0,02
Exhaust: opener 0,08 - closer 0,1

Vertical
Intake: opener 0,13 - closer 0,07
Exhaust: opener 0,1 - closer 0,03

That really surprised me, as most of the clearances have decreased. I was under the impression that the clearance would increase with use.

What am I to make of this? Some of them will need adjusting obviously, but what could cause the clearance to decrease?
Could that be valve stem wear? The bike has about 28.000 km's on it, so nothing to crazy.

 

[ducvet]

I would say you did something wrong then... or now.
Your data does not add up as openers tighten and closers loosen under normal wear.
You show openers tightening as well as closers.

verify you are measuring correctly, do it a few times and then adjust. Given you are getting readings that do not make sense check them again after a while but I would not run to the next service interval.

 

[Andreaz]

All your openers has decreased. Seems correct, but the closers should have increased. Turn your engine a few times and check closers again.

 

[ducvet]

His vertical opener went from
"Intake: opener 0,2 " to "Intake: opener 0,13 "
That is in the wrong direction.

 

[Andreaz]

His vertical opener went from
"Intake: opener 0,2 " to "Intake: opener 0,13 "
That is in the wrong direction.

In my experience, the openers do get tighter. That's why we set the closer clearances tight and the openers at approximately 0.10 mm.

Going from 0.20 mm to .013 mm on opener clearance seems correct to me. Am I missing something or reading this wrong?

 

[blackhyper]

perhaps it would help the inexperienced if we expanded a bit on why clearances change - i expect it is mostly down to valve seat wear, but i'm no expert here
if seats wear, opener clearances will reduce (because the valve tip gets closer to the rocker) - not sure how the logic goes for closers, but i'm assuming its as the valve sits lower in the seat, the closer clearance grows
very happy to be corrected because i'm sure that this situation will occur for many peole
and there's always the possibility that either or both measurements weren't that accurate - i've had that problem before
rory

 

[JEFFRPM]

That is correct
Not only seat wear the valve does the same thing........wear

Run it hard it wears faster run it really hard & those POS closer half rings either wear faster or break sometimes both.

 

[BOTT]

Generic Lash Loss:
1. Valve: More or less holds its length, but the face can pound a groove hitting the 45°. It's slight, but closes gap.
2. Seat: There is a peak cut of 45° [fas] at the seat, is pounded on the close of valve. The peak rounds, begins to flatten out, moves up to close the gap.
3. Machined head: Where the soft aluminum is having that pounding at the seat, condenses the soft metal to move the set up higher in the head, and closes the gap a second way. You can see and feel a lip-sink at the head.

Shims go down is size, not up in size.