Topica Loopframe_Guzzi Archive


Subject: RE: Leak Down and Compression Numbers

Author: Greg Bender

Date: May 2, 2005, 6:32 PM

Post ID: 1718801677



Thanks Lannis, that's good to hear.

Lannis wrote:
 
Greg -

A leakdown rate of 5% indicates a top end in excellent condition. The
compression test doesn't add any engine condition information to that,
except to tell you that you've got a lower compression engine
configuration for some reason, maybe different pistons or a base plate
on the cylinders or something.

I've had Britbike and Jap engines with a leakdown rate of 30% that still

ran well, though they were a bit hard to start and didn't idle very
good. But an engine can be very leaky and still pull well at high RPMS
where there's no time for leaks to affect things....

Lannis

 Greg Bender wrote:

Okay, the leak-down tester arrived today and I headed out to the garage
right after work. Here is what I found both for compression and
leak-down:

Compression values (taken with the engine fully warmed up the other day
before I destroyed my breather box):
Left: 130
Right: 130

Leak-down values (taken with the engine stone cold. yes, I know they
should be taken with the engine warm, but I don't have a breather box
just yet. I would suspect these values will increase with a warm engine
due to an expansion of materials AND the associated ring gap???):
Left: 5-6%
Right: 5-6%

I could not detect any air escaping from either the intake or the
exhaust on either cylinder. This is in line with what I would suspect
given the head work that I had done. I could not detect any air escaping


from either the base gasket or the head gasket. I did detect air
escaping from the crankcase via the oil fill hole. This indicates
ring/piston/cylinder wear to me.

But, everything I've read indicates that 5-6% leakage is not bad. Am I
misinformed? Do I just need to be patient and re-run the test when I
have my breather box back installed?

Regards,

Greg Bender
1971 Ambassador
2000 Quota
http://www.thisoldtractor.com/gtbender

Florida MGNOC website
http://www.thisoldtractor.com/fl_mgnoc

Minnesota MGNOC website
http://www.thisoldtractor.com/mn_mgnoc



Regards,

Greg Bender
1971 Ambassador
2000 Quota
http://www.thisoldtractor.com/gtbender

Florida MGNOC website
http://www.thisoldtractor.com/fl_mgnoc

Minnesota MGNOC website
http://www.thisoldtractor.com/mn_mgnoc

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