Moto Guzzi Valve Adjustment
the Valves on a Moto Guzzi V-twin
by Steve Saady ([email protected])
Guzzi valves is a fairly easy job. Here's what you
have to do for a basic valve adjustment:
Make sure the engine
is cold; best to do this first thing in the morning after the
bike has been sitting all night.
Place the bike on the
Shift to the highest
gear you can get it in; sometimes it helps to jog the rear wheel
with one hand as you push the shift lever to get it in gear.
Take off the
Put a socket wrench
on that big alternator nut, I think it's a 23mm. I know a
15/16" will work as well.
Remove both valve
covers and spark plugs.
If you know the heads
do not need re-torquing, skip to step 14.
Take off the rocker
arms. They are held in place by a shaft, which is held in place
with an 11 mm hex-head. When removing the rocker arms, go slow.
There is a washer, spring, and another washer on top of each
rocker arm. One washer is copper, one is steel. Pull
the arm out too fast, you will lose parts like I did.
Also, BEFORE YOU PULL THE LAST ROCKER ARM OUT, note the
order of the washers. I think bottom to top, it is steel
washer, spring, copper washer.
There are 6 head
bolts per cylinder: two under each rocker arm, one under the
10mm hex cap at the top of the cylinder, and one by the spark
plug. Use a long 10mm Allen key w/ an adjustable
(Crescent) wrench to open that cap. It is not reverse
threaded, mine was tight as hell.
Loosen all 6 of the
head bolts just a little bit to break them. Use a torque
wrench and in a criss-cross pattern, tighten them to 30 foot
pounds. Go ahead and do the other cylinder.
Leave the head bolts
at 30 foot pounds overnight.
After leaving for at
least a few hours, in a criss-cross pattern, tighten each head
bolt to 35 foot pounds.
Re-install the rocker
Remove the rubber
cover (the one that's about the size of a quarter) on the right
hand side of the engine so you can see the flywheel timing
Turn the rear wheel
in the direction of normal travel.
Note the direction
that the alternator nut rotates.
Put your thumb over
the spark plug hole.
Rotate the alternator
nut in the direction of normal travel as noted above. Rotating
it backwards will not break anything, but you will not get a
good valve measurement because of slack in the valve train.
When you feel it
pressing air out against your thumb, begin to look in the timing
hole (where the rubber cover was) for the "S" (if your
thumb is in the left spark plug hole) or the "D" if
you are on the right cylinder.
Line up the
"S" (Left cylinder) or "D" (Right cylinder)
flywheel marks, loosen the lock nut on the intake or exhaust,
adjust the gap and tighten the lock nut. Repeat for other valve
on the same cylinder (* See note below).
Repeat for other
Use 8 foot-pounds of
torque for the valve cover bolts.
Put your plugs,
covers & wires back. make sure to get that socket off
your alternator nut before starting so you do not ding your
NOTE: * If you
have doubts about the S & D marks' accuracy, GENTLY use a
screw driver or other probe in the spark plug hole while SLOWLY
rotating the 23mmm alternator nut. Mine were accurate, and
Guzziology does not mention
Special thanks to Winter Colby,
Lowside, and Guzzi Godfather Wayne Orwig!
this inaccuracy, BUT, it is easy enough to check. Just be
careful. You do not want to ruin a perfectly good screw driver!