Seems all the new-model Guzzis since the EV that have tachs have shown problems with intermittently working or totally dead tachometers. Sport 1100s and Daytonas seem especially prone to these problems. Worse yet, the root cause of the tach problems -poor
grounds - can also affect your charging system.
On the Sport 1100i, the speedometer and the tachometer have ground wires under the brass/rubber mounting bushing. Somewhere, somehow, those ground wires go through the wiring loom to ground. The problem is: under the bushing, electrical connections can corrode, negating their value as grounds and causing the tachometer to quit and/or the instrument lights to waver or go out. The actual grounding point may or may not be on the fairing subframe. The fairing subframe IS the ground return point for the voltage regulator though, and the mounting bolts are not an acceptable ground return path after a few years because of corrosion. When this happens, the regulator can reference itself to a voltage higher than the main chassis and a slew of problems can ensue.
There are several things you can do. All of them require removing the fairing.
1.) You can clean the connections on the bottom of the instrument housings and that will probably work. Temporary fix.
2.) You can remove the fairing subframe and clean the mount points and hardware. Arduous temporary fix.
3.) Run a large ground wire from the voltage regulator housing to the engine case. From the regulator housing run smaller ground wires out to the instrument housings using the other brass/rubber mount and leave the originals in place. This is by far the most reliable way to ensure that no electrical maladies arise as a result of the poor choice at the factory of using the fairing subframe as the ground return path.
I did #3 to my bike several months ago, and the tachometer came back better than new, rock steady, and my instrument lights never quaver any more. (Addendum: the tach light started getting flakey, but the tach itself was fine. Bad bulb socket fit to the tach. I added a ground wire to the bulb socket itself and all is well.)
I will reiterate that it is extremely important that the voltage regulator have a very good ground reference to the engine case. Anything less may eventually lead to the failure of the regulator, ECU, and many other electronic components on the bike. For the Sport
I 100i/Daytona RS (and probably the carb Sports, too) the ground path using the fairing subframe was a very poor design choice. It is relatively easy and inexpensive to fix. Do so BEFORE you suffer an electrical problem. Peace of mind is a wonderful thing.
In reference to the non-spine frame models. I have a 1997 California 1 100i. I am not worried particularly about the voltage regulator mount on that model because it is frame mounted to the same frame as the engine. An extra ground wire would certainly not hurt, but I suspect that it would be unnecessary in the long run. However, my tachometer is the most wildly fluctuating and inaccurate gauge I've ever seen. Unless I press on it while riding, then it behaves as it should. Almost certainly, the ground is the culprit. When I get
industrious, I will add additional ground wires to the instruments on the California and I fully expect all of the erratic behavior to disappear. Should you experience tachometer failures on your late model Guzzi, try grounding the tachometer case with a wire to a known good ground point and see if it returns to normal before jumping to the conclusion that the tach is dead.
And...
The tach is dead, the tach is dead. Long live the tach. Seriously, it may not be dead, at least, not the way you suspect, as in fried components. My tach failed once due to a bad ground. Not at the grounding wire, but INSIDE the tach housing. The instrument case
mounting studs can break loose from the aluminum housing and that IS the ground return for the tach electronics. In stock form, only one of these studs is connected to the ground wires from the wiring harness. Murphy's Law applies in full force here. The one stud you
need - will be the one that breaks loose. JB weld can cure this, but you have to gently pry the tach apart, JB Weld the inside portion of the stud back onto the case and reassemble the tach to remedy this problem. It's a cheap fix and reliable, but not for the ham fisted.
Also, there are TWO mounting studs and I strongly encourage the use of both as grounding points by adding additional ground wires.
Another tip:
On the Sport I 100i the tach wiring has a jumper under the tank from the instrument wiring harness to the FI wiring harness. It is possible to disconnect the jumper when putting the gas tank back on the bike if you mis-position the tank and force it down. Well, Duh ... no-one to blame but myself.
Because the fairing on the Sport 1100i is such a pain to remove and reinstall, I recommend Will Creedons advice to remove the vapor recovery plumbing in its entirety. I don't think the smog police will notice. (Odd, the canisters had to be removed from the California 1100i to fit the Givi brackets on for the bags. What a shame.) The fuel overflow and vent on the bottom of the tank can be teed into one hose routed down to the rear of the transmission. Leaving the tee loose enough to remove with the fingers makes the tank removal process a lot easier. In normal usage, the overflow and vent will never see any real fluid, so the loose connection isn't an issue.
I also recommend routing the fairing wiring through a standard automotive connector, like a trailer connector. This avoids the requirement for a set of long nose pliers to reconnect the turn signal wires.
Buy a set of ball end allen wrenches. That makes pulling the fairing a lot easier because you can access the mount screws without removing the mirror pivot bolt etc.
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I did my California tach two months ago and it is better than new for needle stability. I found the same to be true for the 97 Sport when I did that
a few years ago. The problem with a lot of these tachs is that the case mounting studs are the ground return path for the meter movement. Although there are three wires going to the tach and one of them is a ground lead, it is apparently only a ground lead for the electronics - not the
meter movement itself. What happens is the tachometer case mounting studs are a press fit into the case with an interference mechanical fit. If they were welded there wouldn't be a problem, but they tend to fracture the mechanical bond after a while screwing up the meter operation. Not everyone has this specific problem, sometimes the meter movement counterweights unglue and fall into the bottom. Beyond the scope of my experience for that one.
It can be repaired though, and for not much money, but requires some patience and if the tach is under warranty, I would push for replacement rather than repairing it myself.
As for removing the tach to begin with? On the California, it's a bit of a nuisance.For the 97 California, remove the headlight, the crosspiece between the tach and speedometer and the other housing screw at the rear of the tach as well as the rear cover of the instrument light cluster. Inside the cluster is a screw into the tach housing. Remove that and as I recall (I am going from memory here and I have certifiable CRS - Can't Remember S?it) you can remove the tach and detach the wires. Putting it back on is an amount of fun equal to or greater than the original process. Be sure to have beer available to relieve the stress but take care to not imbibe so much that the process becomes impossible. The (somewhat) easy part is next. Lay the tach face down on a piece of cardboard or an old dishtowel (go ahead, use a clean dish towel, just don't expect me to explain it to your wife...) and using a very small flat blade screwdriver, start prying the bezel lip upwards away from the tach case that it is rolled over on. Just do a little bit, move a few degrees around the case and do it again. A little bit of lift each time. After you've gone around once or twice, you can use a bigger flat blade screwdriver to pry the bezel lip to a nearly vertical position. Once you can pull the bezel off of the tach housing, you remove the three screws on the back of the tach housing and remove the guts. Set them aside. Look into the housing and you'll see that the mounting studs are one of those assembly line press fits. There is a very high probability that either or both of them wiggle a tad (or if you have had too many beers before tightening the tach onto the mounts, a stud has pulled completely loose. One of mine was. I'm special, I don't need the beers as I am digitally dyslexic and ambi-klutztrous). Any movement whatsoever is an indication that the ground path is screwed up electrically and the stud needs to be re-secured. Since very few of us have the skill or equipment to heliarc the damn thing in place, only a really good epoxy will do. Use a metal loaded one to help with electrical conductivity - something like JB Weld in the USA and who knows what anywhere else. A dab on the outside of the case and a large gob on the inside. Let it sit the full cure time - you don't want to do this twice. Put the guts back in and with the bezel face down on the towel, or yesterdays newspaper since your wife caught you using her favorite towel with the little house and white picket fence on it and you're now out in a cold garage with no beer because she took that away too, and gently start bending the bezel lip back down around the tach housing. A bit at a time and work your way around. At some point it becomes possible to take a wooden stick or something similar and a small hammer finish mashing the lip down tight to the tach case.That's pretty much it, put the silly thing all back together (the California's have some pretty berserk mounting hardware) on the bike and take it for a ride. You should get a rock solid reading. In accordance with Vaguelia specifications, all Moto Guzzi's are perpetual motion machines. I can prove it. The tach always reads at least 500 rpm. I didn't care to try and fix that.
Carl Allison
Modesto, California
97 MG Sport 1100i "Bright Red Italian Bugswatter"
97 MG California 1100i
MGNOC 17546
http://home.pacbell.net/guzzi007/sportissimo.html
