klr650 valves **correction**
Posted: Sat Jun 14, 2014 1:53 pm
Luc, Listers,
I made a mistake in the nomenclature in the valve wear paragraph below.
I wrote seat and it should be face. I've posted the correction below.
Sorry for any confusion.
Best,
Jeff Saline
The Beautiful Black Hills of South Dakota
75 R90/6, 03 KLR650
On Sat, 14 Jun 2014 11:02:57 -0600 "Jeff Saline salinej1@...
[DSN_KLR650]" DSN_KLR650@yahoogroups.com> writes:
On Fri, 13 Jun 2014 12:47:17 -0700 (PDT) "Luc Legrain
zrislois2klr@... [DSN_KLR650]" DSN_KLR650@yahoogroups.com> writes:
Ladies and Germs ,
It's been quite while since I posted . I finally stopped procrastinating,
and on this 5th rainy day, finally decided to do a valve check .
Background.. A19 ..36436.2 miles ; first and only valves check was done
at 1500 miles ( bought it brand new )
here is what I have : intake right 0.012m/m
intake left 0.004 m/m ( only guessing
on this one ,my gauges don't go below .006 mils)
exhaust right 0.011 m/m
exhaust left 0.015 m/m
no ideas what size shims are used (number upside
down ) can't know with out removing cams .
34936.2 miles ago I got from Fred that little plastic can with 16 (?)
shims in ,kept oiled and hidden took me 2 hours to find the booger !
Before I take the cams off please tell me what size shim I need to use .
Don't wanna use the calculator .. (lazy) . I want to be on the top end of
the specs , so I can ride happily ever after !
Thanks for the feed back .
<><><>><>
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Luc,
I'm gonna question your measurements. I see from your post today they
are in mms. The conversion for mms to inches (I think in inches so that
is what I use) is 25.4. So taking your measurements and converting by
dividing your measurement by 25.4 here is what I get:
right intake 0.012mm = 0.0005"
left intake 0.004mm = 0.0002"
right exhaust 0.011mm = 0.0004"
left exhaust 0.015mm = 0.0006"
I don't know that I have ever seen a feeler gauge less than 0.0010".
So I'll suggest all your measurements are incorrect.
One of the reasons I work in inches is that is how I was raised and that
is how I think. I can work in metric if I have to but it becomes work.
For the valve adjustments the shim change sizes by 0.002" per size
change. For me that makes conversions simple and easy to do in my head.
Clearances for the KLR valves are intake 0.004"-0.008" and exhaust
0.006"-0.010".
So if you redo your measurements you can quickly figure out the changes
like this example. Say the intake is at 0.003". You want 0.008" which
is a change of 0.005". Shims only change in sizes of 0.002" so to keep
from going over you can only change the shim two sizes (0.004") thinner.
If the shim in place is a 260 you would go smaller two sizes to a 250 and
the clearance would then be 0.007" which would be as close as you could
get. Shim sizes change like this: 275, 270, 265, 260, 255, 250, 245,
240, 235, 230 etc. I'm not sure how small you can go but by 210 you
would for sure need to be considering doing a valve job on the head.
You asked about how valves wear. The valve is shaped kind of like a
mushroom. You have the head of the valve like the head of a mushroom.
And you have the stem of the valve like the stem of a mushroom. In the
head where the valve is placed is a seat. The head of the valve has a
machined surface called the **seat** CORRECTION: SHOULD BE "FACE". The
face of the valve which is on the bottom side of the valve head mates
with the valve seat in the head to make a tight seal. This fit is a
precision fit when correctly done and is the seal for the combustion
chamber. The valve and seat wear as they slam together in operation. A
valve on the KLR opens and closes every other crankshaft rotation. So at
idle of 1,200 rpm the intake valve is opening and closing 600 times a
minute or 10 times per second. As the valve face and seat wear it allows
the valve to move deeper into the head. This causes the valve stem to
move closer to the cam which is the clearance you are measuring and
adjusting. The stem normally doesn't wear shorter it is the valve
seating deeper into the head which is what you compensate for by
adjusting the valves.
Along this same line of thinking... clearance is important as it adjusts
when the valve opens and closes in relation to the cam/crank and also for
how long a valve is closed allowing heat to transfer from the valve to
the seat/head. A tighter valve clearance will open the valve sooner and
close it later which might allow more flow. At the same time it is
allowing the valve less time against the seat and that reduces heat
transfer allowing the valve to get hotter and probably accelerate wear.
If the clearance is too small, as the engine gets hot the valve expands
from the heat and could be held open allowing leakage. In some cases it
can be so bad as to keep the engine from running and will also cause the
edge of the valve to burn.
Hope this is helpful.
Best,
Jeff Saline
The Beautiful Black Hills of South Dakota
75 R90/6, 03 KLR650
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