Subject: Re: start question
Author: Patrick Hayes
Date: May 7, 2001, 12:04 PM
Post ID: 1706628069
In a message dated 5/7/01 11:54:10 AM Pacific Daylight Time,
klru-@webspan.net writes:
<< But then again, I think the pinging might have been caused by
the 1/4 tank of 9 month old gas mixed in with the fresh stuff I had just
filled up with. >>
You old loopers. Remember that there are NO valve guide seals on a Guzzi
head. If the valve guides wear just a little, then the intake stroke can
suck a small quantity of oil between the guide and the valve stem. Actually,
a small quantity is good as that is what lubricates the guide and stem.
However, with age, a small quantity gets to be a slightly larger quantity.
Miniscule amounts of oil vapor wreak havoc with the 'relative octane rating'
of your air fuel mixture. Pinging is the result. When things get real bad,
you can suck enough bypass oil to see blue smoke on downhill deceleration.
But, pinging will occur long before any visible smoke occurs.
So, if you've got more than 30K miles on your cylinder heads, you'll probably
get pinging on hot days no matter what you do with the ignition system. The
only real cure is new guides.
Patrick Hayes
Fremont CA