My Bosch Rotor Needs to Magnitized?

[Barry]

The bulb that is in my bike is different than the bulb you are talking about.It is used in the illumination of Ashtrays in Audis.It is about 1/2 the diameter of the 168 (t3?) bulb you guys are talking about.

Gumby has it right.

With nothing better to do I pulled my tacho off the bike and sure enough there are different sizes of lamp in there. 1,2 and 5 are the commonly available 3W wedge type lamps designation W2.1 x 9.5D.  3 and 4 are miniature wedge lamps designation W2 x 4.6D  With the aid of a low powered microscope I confirmed that these miniature lamps really are 1.2W

When you look at the picture in an 81 - on manual the lamp holders are the same i.e. 3 and 4 (oil pressure and gen lamps) are still shown as miniature W2 x 4.6D but they are listed as 3W.  When I checked an automotive lamps catalogue  it seems these miniature lamps are theoretically available in 3W which is a surprise given how small they are. When I looked on line I could only find them in 1.2 W and 2W versions.

[Bob_Roller]

Those smaller bulbs look like the same bulbs that are in the status lights on my Guzzi, charge, oil pressure, high beam, neutral, etc .....

That gives me some motivation to get the resistor installed in the charge light wiring on the Guzzi .

I still have a very dim charge light illuminated, only visable when it's dark when I leave for work .

[montmil]

The current issue of Airmail, the monthly publication of the ABC, has an interesting article in Airtech written by Oak Okleshen. Oak answers a concern from an '83 R80RT owner who has a very dim GEN lamp that's visible only in the dark.

The article is too long to reprint here in its entirety but I'll present the highlights with the assumption that the battery side in the closed loop of the charging circuit is in good condition. That's good battery, connections all tight and corrosion free.

Oaks states that, when the engine is running, the two sample voltages on either side of the lamp will be close in value but not alike. One may be off a volt or two, allowing the dim bulb glow.

Oak's tips are:

1. Battery charge current is too high. There may be a weak cell in an otherwise functional battery.

2. Fuses. Remove them. Clean fuses and holders. Rotate to insure good contact. (I would add a bit of dieletric grease.)

3. Remove the starter control relay. Clean the relay blades and squirt some contact cleaner into the socket. Not WD-40. Plug the relay in and remove it. Do this several times to insure good contact. (I'm still adding dielectric grease on the blades.)

The individual that had the dim GEN bulb on his R80 went through all of Oak's steps and also installed new fuses. GEN lamp is now totally extinguished while riding. As the R80 owner stated, "I'm not sure what the culprit was."

This is one of those potential fixes that takes a little time and, usually, zero cash. Hopefully, someone may find that Oak's tips will cure their dim GEN bulb.

[Semper Gumby]

THANK YOU BARRY!

If there is a higher wattage version of that freekin tiny bulb I'd love to have it.  At the moment I have the GE90 attached to the RH side of my aircleaner.  But then if I drop something in the dark with the bike cut off I can now find it!  

On the plus side of this whole adventure - the hot (+) side of the coil is a great place to wire in a voltmeter.  If ever there was a canary in the coalmine for the volts going to your ignition, this is it.

BTW - I can now tell the difference between the Tacho of a 79-80 bike and a 81 and older just by looking at the face of the Tach.

[Bob_Roller]

A tip I saw on the Guzzi site, put o-rings on the metal tangs of the fuse holder, to add extra pressure between the fuse and the holder .