Subject: Re: STARBOARD? (Is that left or right?)
Author: Patrick Hayes
Date: Apr 6, 2003, 11:28 AM
Post ID: 1712525302
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In a message dated 04/06/2003 10:48:43 AM Pacific Daylight Time,
3haw-@bluefrog.biz writes:
| told me not to hold the gauge on there too long as it would render an inaccurate reading. He told me that I should get a reading anywhere from 70 to 120. |
Dude, you SERIOUSLY need to find a new mechanic. Don't take anything more
valuable than your lawnmower here. You really need to have around 150+ psi
on a Guzzi motor. Variation between the sides not more than 10%. If you
have 70 to 120 compression readings, there are only a few things that can be
wrong.
First you didn't hold the throttle wide open during the test (an incredibly
common error).
Second, you have burned valve surfaces.
Third, you have scored rings or cylinder walls, or broken rings.
Fourth, somebody disassembled the motor and didn't get the crank/cam
relationship set back properly.
My vote is for the FIRST scenario. Ignore this guy. Do it yourself. Do it
right.
Furthermore, what does time have to do with it? You remove the spark plugs,
attach a compression tester, open the throttle, and spin the motor with your
starter. After about four or five revolutions, the system maxes out and you
can't compress any further. That's your reading. Doesn't matter if you
crank it FIFTY more times, it won't get any higher. You won't hurt anything
(except maybe burn up your starter if you crank it continuously). And you
won't falsify any readings. Max compression = max compression.
Patrick Hayes
Fremont CA
PS: Good luck with the lawnmower!
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<HTML><FONT FACE=arial,helvetica><FONT SIZE=2>In a message dated 04/06/2003 10:48:43 AM Pacific Daylight Time, 3haw-@bluefrog.biz writes:<BR>
<BR>
<BR>
<BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">told<BR>
me not to hold the gauge on there too long as it would render an inaccurate<BR>
reading. He told me that I should get a reading anywhere from 70 to 120. </BLOCKQUOTE><BR>
<BR>
Dude, you SERIOUSLY need to find a new mechanic. Don't take anything more valuable than your lawnmower here. You really need to have around 150+ psi on a Guzzi motor. Variation between the sides not more than 10%. If you have 70 to 120 compression readings, there are only a few things that can be wrong.<BR>
<BR>
First you didn't hold the throttle wide open during the test (an incredibly common error).<BR>
Second, you have burned valve surfaces.<BR>
Third, you have scored rings or cylinder walls, or broken rings.<BR>
Fourth, somebody disassembled the motor and didn't get the crank/cam relationship set back properly.<BR>
My vote is for the FIRST scenario. Ignore this guy. Do it yourself. Do it right.<BR>
<BR>
Furthermore, what does time have to do with it? You remove the spark plugs, attach a compression tester, open the throttle, and spin the motor with your starter. After about four or five revolutions, the system maxes out and you can't compress any further. That's your reading. Doesn't matter if you crank it FIFTY more times, it won't get any higher. You won't hurt anything (except maybe burn up your starter if you crank it continuously). And you won't falsify any readings. Max compression = max compression.<BR>
<BR>
Patrick Hayes<BR>
Fremont CA<BR>
<BR>
PS: Good luck with the lawnmower!</FONT>
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