Yet more Guzzi fettling

This is a tale of much faffing.

I was running the Guzzi in last week after its engine rebuild and it
was vibrating a bit at idle and surging a bit on light throttle,
otherwise running quite well.

Friday evening I balanced the throttles, which smoothed things out
considerably. Now this should have been a ten-minute job, and that
includes looking for the vac gauges. It wasn't was it? The bloody idle
adjuster screw had seized and the flexi-drive had rusted through and
snapped off, and it was now idling just a bit too fast.

So, yesterday, off came the side panels, seat, tank, airbox and, after
a bit of faffing, the throttle bodies. I sawed a slot into the screw,
got it out (first time I've used an impact driver in *years*) and
cleaned & lubed it. As a bonus I replaced the throttle cable, which
was badly frayed.

OK so far. All back together and at first, it seemed normal. Then I
found that the revs were unstable and it began idling badly. Checking
with the vac gauges, it was way out of balance and there now wasn't
enough adjustment in the external screw adjuster to balance things.
Arse.

Once more, off came the side panels, the seat and the tank. Now I
found that I'd disturbed the throttle butterflies during yesterday's
fix, so I spent a merry hour anna half (broken only by a dash indoors
to record MGP) setting the butterfly balance up. As I don't have a
remote fuel tank, I did it very roughly on the starter motor. This is
a coarse adjustment; the fine tuning is done with an air bleed screw.

This time I didn't reassemble everything, having eventually learned my
lesson (I'm a slow learner), but the throttle balance was about right.
Some fine tuning and... the revs still took way too long to settle
after blipping the throttle. Bugger.

Now it looked like it was running lean at idle. Rather than use a
Colortune I decided to dust off my ancient CO analyzer. Mucho more
faffing ensued, partly due to the fact that the CO meter readings
wander all over the place; setting it up and using it are an exercise
in patience and you need to check it hasn't drifted out of calibration
after taking readings, too. It usually does. I eventually decided that
the bike *was* running lean. Twiddling the idle mix screw on the ECU
didn't fix it, so I started playing around with the TPS position.
Oddly, I eventually ended up with the TPS adjustment very near where I
started out, but now the mixture's about right, i.e. rather richer
than Guzzi specify.

Today I *was* going to take off the pannier frames and repaint them
before they fall apart from rust, but that'll have to wait.

My back aches from bending over the bike and my hands are sore from
twiddling things in hot confined spaces and catching them on sharp
edges, but it is done. Maybe, just maybe, that'll be it now.

 

On my T3 balancing the throttles makes no sense at all. I spend ages
fucking about with the throttle stop screws after getting the cables to
operate uniformly. Gauges work totally opposite then suddenly seem to
match. No idea why.

The bike is so loud and I work in an enclosed courtyard surrounded by
flats that one Sunday morning I had an empty milk bottle thrown at me. I
now take it out on to the Downs to balance the carbs.

I tend to only do it every 1000-2000 miles.

Other bikes I've done have been no bother but the Guzzi is an arse.

 

I've never had problems balancing the throttles, and it does make a
significant difference on the Quota. What *has* been a PITA is idle
mixture; I can piss about for absolutely ages and seemingly end up
with everything pretty much as I started out, but it's then sorted.
This weekend's fettling, from that POV, was nothing special.

Heh. If you *will* run loud pipes...

Fortunately my Quota seems to be pretty good in that regard; I can't
remember the last time I felt the need to balance the throttles, which
is probably why the idle screw seized.

 

This might help:

On my ShiteOldBoxer carb balancing took a minute.

Disconnect one plug lead.
Set the tickover at 400rpm or whatever it just doesn't stall at with the
active carb.
Repeat for other side.

With both leads on turn down tickover screws if necessary by a ballhair.
It often wasn't necessary, as the combined tickover was usually spot on.

Sorted.

Of course, it was nice to set the thing up properly with the gauges, but
the above procedure worked well when miles from home and some roughness
developed.
--
Dave
GS850x2 XS650 SE6a

Teach a man to fish and he and his pikey mates will have the
river cleaned out in a day.

 

Done this and it works. Not quite as well as using tools but If you
have a good ear it is possible to get them close enough by this method.
If you have a fabulous ear you can get them spot on and even get them
pretty good with 4 cylinders.

 

True - CBs don't care about disconnected bits. I must say, the lack of
eleccy nition wasn't a problem on that old heap, but it might have been
nice to see what difference it made to economy in its ultimate
configuration.
--
Dave
GS850x2 XS650 SE6a

Teach a man to fish and he and his pikey mates will have the
river cleaned out in a day.