Compression test - 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 03-11-2014, 08:52 PM Thread Starter
1st Gear
 
Join Date: Apr 2012
Location: Lower Alabama
Posts: 60
Compression test

So I bought another KLR and when I went to look at it the guy kindly replaced the frayed clutch cable since he had a new one and took the tank off so I could do a compression test. Well, obviously I have never done a comp test on my other KLR's and it failed at about 60psi. We surmised that a standard compression gauge in the spark plug hole does not work on a KLR due to the automatic compression release.

While the comp test did fail and made me a little nervous, it just ran way to good to be any major problems.

Does anyone know the trick to a good compression test? I saw one on youtube but the engine was on the bench and I couldn't really see what was connected or what else may have been done to get the 150psi compression.
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Old 03-11-2014, 10:03 PM
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Delta Dog,
We kinda' need to know what year and how many miles is on this KLR?

You need a compression adaptor which is the full 3/4" thread, like the spark plug. And a fully charged battery and the throttle held 'WIDE OPEN'.

I will suggest, things are mostly 'fine', being it does start, at least above 60F.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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Old 03-11-2014, 10:13 PM Thread Starter
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Join Date: Apr 2012
Location: Lower Alabama
Posts: 60
The bike is a 2005 with 9,800 miles.

I did hook up a good compression gauge with the correct fitting. The battery was strong but did not hold the throttle wide open (I am used to testing outboards....no throttle required).

Anyway......the compression leveled out at 60psi each time the start button was engaged for 3-5 seconds.
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Old 03-11-2014, 11:02 PM
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Join Date: Oct 2011
Location: Lac La Biche Alberta Canada
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60 psi is about all you are going to see on these bikes with a static compression test. The automatic compression release prevents doing an accurate compression test. It can be done by disabling the ACR but that is a lot of work and involves taking off the valve cover. The owner isn't likely to allow that. If it runs good and doesn't blow a bunch of smoke you are likely good to go.

Regards....justjeff

Edit: Ha!! FOUND IT!! This is the thread where Tom Schmitz and SkiBumBrian did an excellent write up on how to disable the KACR and perform a compression test. http://www.klrforum.com/showthread.p...highlight=KACR

It's not a Tractor....It's a LOCOMOTIVE!! Chugga Chugga
Woooo WOOOOO!!!!!

Last edited by justjeff; 03-11-2014 at 11:11 PM.
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Old 03-11-2014, 11:16 PM
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They should have done away with the KACR the same time they dropped the kick start. I took care of that issue with a KACRectomy
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Old 03-11-2014, 11:18 PM
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A LEAK-DOWN TEST is preferred to a compression test on a KLR with a functioning KACR (Kawasaki Automatic Compression Release).

The KACR can be disabled, once it's accessed by removing the valve cover. But; that's lots of work, as mentioned.

EDIT: Typed before I saw the link in the above post.
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Old 03-11-2014, 11:24 PM
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Location: Lac La Biche Alberta Canada
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Quote:
Originally Posted by Damocles View Post
A LEAK-DOWN TEST is preferred to a compression test on a KLR with a functioning KACR (Kawasaki Automatic Compression Release).

The KACR can be disabled, once it's accessed by removing the valve cover. But; that's lots of work, as mentioned.

EDIT: Typed before I saw the link in the above post.
HA!! Beat you to the button Damitoclese!
jj

It's not a Tractor....It's a LOCOMOTIVE!! Chugga Chugga
Woooo WOOOOO!!!!!
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Old 03-12-2014, 08:01 AM Thread Starter
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Join Date: Apr 2012
Location: Lower Alabama
Posts: 60
Thanks guys!!

I am gonna chaulk this one up to just skipping the compression test on a KLR because I have no intentions of disabeling the KACR. I just thought this was gonna be a good, quick test before buying..........just like an outboard or atv.
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Old 03-12-2014, 11:27 AM
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Join Date: Nov 2009
Location: Lander, Wyoming
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Quote:
Originally Posted by Delta Dog View Post
The bike is a 2005 with 9,800 miles.

I did hook up a good compression gauge with the correct fitting. The battery was strong but did not hold the throttle wide open (I am used to testing outboards....no throttle required).

Anyway......the compression leveled out at 60psi each time the start button was engaged for 3-5 seconds.
Delta Dog,
On the outboard motors, the control box will only allow 'X' amount of throttle opening and still allow the starter motor to operate.
You Should Use as Much as you can get.
You should 'Crank it' till the gauge stops gaining.

Chances are at 9800 miles Some or All of the valve tappets need to be re-shimmed.
Chances are, the previous owner never did it, nor had it done.
Valve shims are available in .002" increments, seldom can you achieve perfect Max. Spec. But always adjust to upper middle or max. spec., if possible.

The KLR compression spec, WITH an Operating KACR is 77-124 psi.
There is NO Spec for a non-operating KACR!
Because it is kinda' tough on the small battery and small starter motor to Crank a 100mm piston against 165-195psi, year after year.

Tight valve clearance can cause LOW Compression, yes?
A tight RH Exhaust tappet, allows the KACR to Hold the RH Exhaust open longer, even less compression.
With 100-120 psi, a KLR starts very well in any temperature I care to ride in WY.

If after valve adjust and confirmed leak-down is nominal, if COLD cranking compression is still less than 90 psi, the KACR pin could be relieved about .010". Concentrating on the peak to the trailing side. We are primarily changing the 'Closing degree of crank angle'.The KACR is in there for 'good reasons', but sometimes even IT needs a little 'tuning'!

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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Old 03-12-2014, 01:39 PM
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Join Date: Mar 2012
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Some speak theory or what they have heard, sone from personal experience. Your compression should be the same WITHOUT the KACR as with one that is disabled. I have been running without a KACR for a couple of years now with no notceable difference or strain on the starter motor. Do what you want but tribal knowledge is just that....
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