Vee Compression Numbers? (cold) - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
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post #1 of 5 Old 03-14-2011, 03:57 PM Thread Starter
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Vee Compression Numbers? (cold)

remember, I took mine with the engine stone cold. Why? I don't know....just did.

What's the threshold, with a cold motor, where you'd get concerned? Anyone??

'06 KLR650
'78 CB750
'04 DL1000

Last edited by maximilian; 03-14-2011 at 06:08 PM.
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post #2 of 5 Old 03-14-2011, 04:22 PM
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The DL1000 service manual describes it as 142-199psi standard, 114 min. limit and a difference of no more than 28psi. (automatic de-comp. actuated)
It follows up with none of the cylinders less than 114 psi.
Difference of no more than 28psi. between cycl., and overhaul engine if below 142psi. even if they measure more than 114psi?
Taken warm engine,throttle full open.
I tend to do leak down checks more now than compression checks.
A leak down test will tell you whether it is the intake valves leaking into the airbox, exhaust valves into the pipes or rings leaking into the crankcase as you can hear the air escaping into these areas. Hope this helps.

Bernie 05-DL-1K
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post #3 of 5 Old 03-14-2011, 07:35 PM Thread Starter
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....update- What about the ACR (automatic compression reduction) system?? I assume that will screw up the test, unless defeated for the purpose of the test....right?? Or no??

'06 KLR650
'78 CB750
'04 DL1000
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post #4 of 5 Old 03-14-2011, 08:48 PM
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Quote:
Originally Posted by maximilian View Post
....update- What about the ACR (automatic compression reduction) system?? I assume that will screw up the test, unless defeated for the purpose of the test....right?? Or no??
The manual states to crank the engine with the starter when doing an compression test which means the auto decompressors are activated and reduce the compression slightly.
Under normal starting conditions the auto decompressors hold one valve open in each cylinder a small amount and reduce the compression to allow the engine to turn over easier.
As soon as the engine starts the auto decompressors deactivate to allow full compression.
The numbers I gave are based on doing it this way as the manual describes it.
What your looking for on a compression test is to hopefully find both cylinders with close to the same reading, this is more important than a real high number.
A cold engine will have a slightly lower reading than what the manual says.
If you decide to do a lot more work on your bike and haven't got a service manual try and find one. Its one of the first things I bought for my bike.
It makes things so much easier. When it saves the first hour of shop time its paid for itself.
Hope this clears it up a bit.

Bernie 05-DL-1K
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post #5 of 5 Old 03-14-2011, 09:16 PM Thread Starter
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Yep...was hoping the compression test was supposed to be done with the acr disabled, thus all valves closed completely. The reason is that my numbers are slightly lower than I'd like.....but that's with it cold and with the ACR in effect. Not "rebuild time" low....but it only has 16k miles on the clock.

Funny, my KLR650, with KACR, shows only 80-90 psi as I recall (due to ACR) thus compression test, on the KLR at least, are worthless (the KLR is tight to the point of being hermetically sealed). They pretty much start when cold or they don't.

'06 KLR650
'78 CB750
'04 DL1000

Last edited by maximilian; 03-14-2011 at 10:06 PM.
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