Subject: Re: Stupid newbie question #1, petcocks
Author: ranjan
Date: Jan 25, 2005, 9:03 PM
Post ID: 1718274208
AJ
I have a 67 V700 with original tamedicks, (petcocks) that do not have any
perforated tubes on either side. These petcocks have flip levers mounted
horizontally that have only 2 positions, on or off.
As Greg stated you use the left one as main tank, and the right as the
reserve, acct. of the tank tunnel acting as a separate reserve tank area.
I think that Greg's left petcock tube with higher perforations could
possibly give you a 2nd reserve if there actually was a reserve position on
the petcock, similar to BMWs of the time. If I run my
R90/6 like my 700, I get 3 reserves. First I run the LH cock on main, 2nd
the RH cock on main, then back to the LH for reserve and finally the RH
reserve hoping the gas station is in sight.
I've never ran out yet, with this much low fuel warnings and a 6.8 gallon
tank. Oh! my aching butt!!
Randy Wilson
SE SoDak
67 V700
97 R1100RT
75 R90/6
68 Shovelhead I'm getting tired of 'renching!
too many, but not for sale
51 Panhead
72 CL 350
79 DT 80 (street legal)
82 XT 550 (not running yet)
----- Original Message -----
From: "Greg Bender" <gr-@thisoldtractor.com>
To: <Loopfram-@topica.com>
Sent: Tuesday, January 25, 2005 5:16 PM
Subject: RE: Stupid newbie question #1, petcocks
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If you are lucky, AJ, you have either one of the two common petcocks
that Guzzi used. One type is chrome plated, and the other type is
alluminum. Both have square bodies and with a little handle/lever that
turns. Now, on to how most of them operate...
When functioning properly (that is, no leaks), the petcocks I described
above are either "on" or "off". There is no "reserve" position (more on
reserve, later). If all is right with the world, the 6 o'clock position
should have the fuel moving through either petcock. Either the 3 o'clock
or the 6 o'clock positions will close the fuel supply.
About reserve...later models (starting with the 850T, I think) used
petcocks with three handle positions "on", "off", and "reserve". Moto
Guzzi used a different technique with the loop frames. Essentially,
there is a tube that is affixed to the top of each petcock (stuck up
into the tank). The tube is perferated with holes so that the fuel can
flow. On the left petcock (in the stock configuration), the holes in the
tube did not start until part way up the tube. On the right petcock (in
the stock configuration), the holes in the tube go clear to the bottom.
The idea being that you turn the left petcock on and run the bike. Once
the fuel level goes below the perforations on the tube, you turn the
right side petcock on and beeline for the nearest petrol station.
This design requires that you have a "cross" installed between the fuel
lines so that one petcock feeds both carburetors. As Patrick mentions,
there are many aftermarket varieties that have been installed on a lot
of the loops, so you really don't know what you have until you take a
look.
To the best of my knowledge, the above information is correct. However,
the wise members on this list will certainly correct my errors. Good
luck!
Patrick Hayes wrote:
AJ Huff wrote:
Guzzi used several types of petcocks and some owners also changed to aftermarket versions. So, it is really difficult for anyone to answer this precisely for you. You'll really have to drain the tanks down to analyze what you have. Some petcocks have two internal stems. One sits higher than the other. When fuel level gets below the higher stem it stops flowing. Turning the valve opens the lower stem for an additional or reserve supply. Some petcocks only have one flow level. You drive the bike on one until it runs dry. Due to the internal shape of the tank there is always an extra supply captured on the non-opened side. Open the second valve and you use that supply as a reserve. Pull your petcocks, disassemble and learn what you have on your bike. Generally, the bikes will run just fine on only one petcock opening unless you have some other fuel flow restriction. Patrick Hayes Fremont CA |
Regards,
Greg Bender
1971 Ambassador
2000 Quota
http://www.thisoldtractor.com/gtbender
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