Stone Problems and their Fixes

This will be a compilation of symptoms experienced by Stone riders and how the problem was resolved. To submit your experiences, please e-mail me: marina@armory.com.

Bubbling tank paint

If your gas tank paint bubbled, you should make sure this fix is performed to protect your new one! PDF Download

Gas Cap Removal

This seems to be a common problem across Moto Guzzis: you're filling up while on a ride and the key sticks in the gas cap. It won't turn. Sometimes a little graphite lubricant will fix the problem (if you can get your key back out!), but sometimes riders solve the problem internally.

I haven't attempted the following fix myself, but here's the description: take apart the gas cap and smooth (with sandpaper, presumably) the cast and green (or grey) plastic pieces, both inner edge and outer edge. Perhaps (some people do it, others don't) snip about half a turn off of the spring, while you're at it. Lube everything up, and put it back together.

Throttle Position Sensor

I experienced a problem with my 2002 Stone such that when I would come to a stop, the engine revs would drop really low and the engine would stall. I could save the engine by keeping on a little throttle while stopping. On hot days, I'd also have symptoms where the engine would stutter and surge in first and second gear. It turned out to be a bad TPS. The bike has been running great since it was replaced (under warranty).

Gear shift lever assembly

This has been a problem since I bought the bike! I guess it was put together on a Friday afternoon. Three days after riding the Stone home, the shifter assembly disconnected from the gear box. I didn't know what it was supposed to look like down there and had it put back together at the shop. Everything was fine until about 4,000 miles on my trip to New York. As I was arriving at my destination, the gear shift lever went floppy again! I had lost a "lock" nut off the assembly. These things are metric size 6. I managed to find a replacement nut at local Ace Hardware (bought a few) and some thread locker since I couldn't find lock nuts. So, I lost another one of these lock nuts on the way home (floppy shifter and another replacement using thread locker). Even later on the trip home, the shifter went floppy again! This time, it was the vertical bolt that is threaded on both ends. It had come free from the top connection. I was able to grasp it well enough with the pliers on my little Leatherman Squirt to screw it back in. After getting back home, I unscrewed and reassembled the whole thing using thread locker; now my shifting is smoother than ever. This is a region I would definitely check for loose nuts before and during any trip. Unfortunately for me, I'm not always sure exactly how things are supposed to look, especially on some of these moving parts. Being stuck in 5th gear when approaching a stop-and-go construction zone is no fun! Lucky for me, I always had somewhere safe to pull over.

Electronic fuel petcock failure

If your electronic fuel petcock fails you can replace it with a manual petcock (part number 01105460). The manual petcock should cost about $20. Both Brian in FL and Jeff in Ohio made this switch.

Jeff says, "If you choose to replace fuel line, you will need 12mm fuel injection hose (BMW dealer or Todd at MPHCycles.com can hook you up there). I used the existing fuel line. The outlet angle on the new valve is 90 degrees instead of 60 degrees, so the best way to do it is to stick the valve up in the tank (don't screw the nut yet), then attach the hose, then screw the nut up and tighten it all up. Now that you have your electrical one off, tape up the connector left hanging on the bike so crud does not get in there. Also, look at your electric one. On mine, the insulation on one of the wires going into the bottom was already split (after only 6,000 miles!) showing bare wires."

Engine Paint Bubbling

This is a known problem for 2002 models with the crinkle finish paint. The paint can take several thousand miles to begin bubbling and peeling off the engine. The good news is that this doesn't affect the performance of the bike. The bad news is that it looks rather ugly. Moto Guzzi North America is offering a small amount of gear/accessories to compensate owners with documentation of the ailment. See your dealer for details on how to report this to MGNA.

When you visit your dealer to report the problem, make sure they document the bubbling paint with the following three photographs: the engine number (kind of tricky to photograph well), the general area of the engine, and a close up of bubbling paint.

Rapid Clutch Wear

UPDATE: A rapid clutch wear problem in 2003 models with a single disc clutch has been addressed by MGNA in a bulletin titled "Technical Information No. 03-2003" on 12 June 2003. Mike Harper reports that, "Basically it states that an extra effort should be made to watch the clutch adjustments at the handlebar, at the end of the cable (lower) and at the lever on the gear cover.

"It further states "Note, finally, that a percentage of clutches may show some abnormal wearing phenomena due to the materials defect. In such a case, you may request a warranty covered work to substitute the complete set with a dual disc set".

It then gives a list of items to order and instructions to use special warranty codes and then states that the alloted time for changing a complete clutch is 6.2 hours."

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