Why does valve clearance tighten up? - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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Old 04-15-2016, 03:58 PM Thread Starter
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Question Why does valve clearance tighten up?

Hi, Well I got valve shims ordered for this 90 that i'm working on. The clearance on the right intake valve/lobe was worst, down to 0.00. Just curious, these are basically solid lifters right? Why does the clearance get tighter over time??
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Old 04-15-2016, 04:08 PM
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Originally Posted by rhubic90 View Post
Hi, Well I got valve shims ordered for this 90 that i'm working on. The clearance on the right intake valve/lobe was worst, down to 0.00. Just curious, these are basically solid lifters right? Why does the clearance get tighter over time??
I could be wrong, but the way I understand it is that over time the valve slowly (and minutely) recesses into the valve seat in the head. Plus the seating area on the valve itself slowly wears. That effectively moves the valve stem up and decreases clearance.

Smarter folk than me will chime in if I'm wrong, lol
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Old 04-15-2016, 07:02 PM
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Yeah thats correct and the valves can stretch too.
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Old 04-15-2016, 08:02 PM
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Quote:
Originally Posted by rhubic90 View Post
Hi, Well I got valve shims ordered for this 90 that i'm working on. The clearance on the right intake valve/lobe was worst, down to 0.00. Just curious, these are basically solid lifters right? Why does the clearance get tighter over time??
rhubic,
There are several reasons.
But the One that I/we fear the most is Dust and Dirt passing thru an Un-Oiled air filter.
Next on my list is, Dust and Dirt passing around an Improperly Installed air filter.
Third might be, Dust and Dirt passing around improperly installed carburetor / air filter Air Duct.
Fourth might be, the lack of 'cushioning' from the removal of Tetraethyl Lead from our gasoline.

Fifth is, just normal wear from normal useage. Perfectly normal and that is Why there is some form of adjustment provided.

How many miles is on your bike and how long has it been since the last valve tappet adjustment?

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 84,000+ miles & counting
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Old 04-15-2016, 10:00 PM Thread Starter
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Very interesting. I haven't tinkered with motorcycles for a long time. Recently picked up this 90 KLR650. It's a project.

46000 miles These shims that came out have different coloration and wear so the valve adjustment must have been done at least once before. Thankfully the cams and bearing surfaces (end caps?) look good.
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Old 04-16-2016, 12:00 PM
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The valve shims could be 2 or 3 different brands or even generations of production.
The numbers are to be installed down, so they don't get rubbed off.
Do the numbers all look like the same font? Really doesn't matter.

At 46,000 miles, your bike should be ready for its Fifth valve tappet inspection. (Break-in, plus 4 more.)
Your bike has apparently had properly oiled air filter service or it would have had more 'tight' valves.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 84,000+ miles & counting
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