Subject: RE: Compression Perplexion
Author: Pete Scheer
Date: Jul 12, 2001, 5:00 AM
Post ID: 1707462813
Barry
My 71 has similar characteristics ( left side plug black and a little oil
residue on the plug.)
But no leak. Anyway I did the compression check and found 165 Left and 160
Right.
But I noticed that I could get different readings when I repeated the test.
Then I noticed as I did the second side that the pressure would go up
progressively as I cranked it. To be a fair test you seem to need to crank
each side for at least 3 compression Cycles. I cant say I took note of
that and I want to repeat the test soon.
Also I want to do the test with a hot engine, just as a benchmark
Pete
-----Original Message-----
From: Barry Dikeman [mailto:bar-@matiacontractors.com]
Sent: Wednesday, July 11, 2001 10:44 AM
To: Loopfram-@topica.com
Subject: RE: Compression Perplexion
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Patrick Hayes wrote:
| In a message dated 07/10/2001 8:27:04 PM Pacific Daylight Time, bar-@matiacontractors.com writes: << I ran a compression test on it tonight and came up with the following: 180 Psi Left (old oily) 165 Psi Right >> Those are OK, but that's about the limit of acceptable variation. Generally not good if variation exceeds 10%. Just checking. When you ran the compression test, were you certain to hold the throttles wide full open during the testing cycles? Some people forget and it causes big errors. A compression test will only tell you the quality of your ring/cylinder seal and your valve face/valve port seal. This test can't tell you anything about the clearance between the valve stem and the valve guide. On older Guzzis, the vavle guides wear oval and the intake suction stroke pulls oil out of the rocker chamber, down past the guide, and into the combustion chamber. This could easily be the source of your oil and is a likely source if you have more than 35,000 miles on the heads. If the leakage isn't real bad, live with it until the winter and then do the heads properly. Patrick Hayes Fremont CA EV, EV, SPII, V-65-C, Monza, SuperAlce MGNOC L-403 |
Thanks Patrick! Yes I did hold the throttles wide open and repeated the
test twice for each cylinder so am fairly certain of the results. Your
diagnosis confirms what I have read and is consistent with what I have
observed on my bike. Any idea how much a professional head-rework will
cost me?
Thanks,
Barry Dikeman
73 Eldo