I am concerned mostly with the overall health of the Guzzi. I have been riding it for the past couple years after 'inheriting' it from a friend. I've gotten the major leaks fixed, but the bike is still burning oil, which I would associate with poor compression.
Over the past year I have rebuilt the carburetors and adjusted the valves, timed the ignition, put stock exhaust pipes back on the bike, and rebuilt the distributor. While performance has improved from 75 mph tops to 85 mph tops, the idle has generally been slowly degrading and getting choppier, more prone to drop below 1000 rpm and simply poop out. Digitally resynching the carbs didn't help with the idle.
In Guzziology, Dave Richardson writes: "It's not uncommon on older big twins with chrome plated cylinders (pre-1980s models except the LeMans I and most LeMans IIs) to see [leakdown] readings of 65% or more on engines that seem ot run fine. They may run but they're really hurting and may have trouble settling into a consistent idle. An engine in this condition will produce significantly less power, use more fuel, run hotter, and be more likely to ping."
I must confess I have a hope that compression is the source of the problem, if for no other reason than my inability to find it otherwise.
All reasonable suggestions entertained...
Gerard
Greg Bender wrote:
Hi Gerard,
If you are getting a compression reading of 175 on each cylinder, what are you worried about? I think 160 is "normal" and 175 may be a bit high, but I'm not certain about that. At any rate, it seems that low compression isn't your problem. What specifically do you want to accomplish?
gerar-@netzero.net wrote:
Hello Loopframers-
A while back I posted about my El Dorado's difficulty idling steady. A group of guys fed me with steady advice. Thanks again, all of you who responded with suggestions.
I finally ordered a copy of Guzziology, and on page 3 of the 'basics' chaper, always humbling, the author suggested the use of a leakdown test
over a compression test. The author explained that Pre 1980s big twins can suffer from leakdown figures in excess of 65% while still seeming to
run fine. However, they have difficulty settling into a steady idle.
I pumped air into the Guzzi's spark plug hole at TDC compression with the valves within spec and I could feel air coming out of the oil drain plug hole. It was not even hissing which worried me. Incidentally a vintage BMW friend came by and we took compression tests as a hoot. 175 psi, both cylinders. I have to be suspect of the compression reading.
I'm looking to milk all information I can about good machinists in the Sacramento and San Francisco areas. I would like to do as much as the teardown myself as I can. I am fully aware I will have to take a whole lot of time and a whole lot of reading, and will probably have to do the
job twice, but I figure nothing quite beats the most 'intimate' of relationships with a bike.