Dash indicator lens replacements

Original lenses

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The following colors were available and were provided complete with the bulb holder.

• MG# 10744900: Amber (dual terminal bulb holder with two 6.35 mm male spade terminals)
• MG# 10744901: Green (believed to be a single terminal bulb holder with 6.35 mm male spade terminal)
• MG# 10744902: Red (dual terminal bulb holder with two 6.35 mm male spade terminals)
• MG# 10744903: Blue (believed to be a single terminal bulb holder with 6.35 mm male spade terminal)
  I cannot locate this part number in any of my spare parts catalogs
• MG# 13744901: Green (believed to be a single terminal bulb holder with 4 mm female bullet terminal)
• MG# 13744920: Red (single terminal bulb holder with 4 mm female bullet terminal)
• MG# 13744943: Red (believed to be a single terminal bulb holder with 6.35 mm male spade terminal)

Moto Guzzi later referenced the lenses separately:

• MG# 10754900: Amber (lens only)
• MG# 10754901: Green (lens only)
• MG# 10754902: Red (lens only)
• MG# 10754903: Blue (lens only)
  I cannot locate this part number in any of my spare parts catalogs

Alternative 1

Thanks to John Allen who sent me this information via e-mail. In John's own words:

As a side note I have been experimenting with using ³⁄₈ inch cast acrylic rod to make replacement lenses for the original lights. I posted a picture of what I made so far, the clear lenses are mine next to the original colored lenses. I can get clear ³⁄₈ inch acrylic rod but not colored (only ¹⁄₂ inch rod in color). If I had a metal lathe I would probably try and turn some colored rod down to fit. The ³⁄₈ inch rod is almost perfect for the diameter, it needs a little sanding to fit inside the old bezel. I've been heat polishing the lenses but I am not happy with the actual finish. I've been spinning the rod on a wood lathe to sand the tops and when I get a few more I'm going to drill the bottom out and then try to Rit dye a few and see if the color will take. Just thought I would throw that out there if anyone else wanted to experiment with making lenses. I will keep everyone posted.

Later, John sent me an update. In John's own words:

I was talking to Steve Odell from the loop list about lenses and he had made some with blue and green using cast acrylic rod turned down from ¹⁄₂ inch diameter by a friend. He sent me a couple pieces, one blue and one green, to mess around with and some advice on how to work the material. I picked up a 4 ft stick of red and a 4 ft stick of amber as that is the smallest lengths you can get reasonably cheap (USD $22.00 for a 4 ft piece, so just two colors is USD $55.00 with shipping). I only used about two inches off a 6 inch piece so I have a lot extra. In fact I just sent Steve a 6 inch piece of red and orange so he can have a full set.

It is actually easy to make once you figure out the best steps.

1. I use a small metal lathe with a really sharp (I hand diamond lapped it) pointed parting tool bit at 2000 RPM and turn the ¹⁄₂ inch rod to 0.405 inch diameter. I turn about a 3 inch length of material right off the chuck and use a live center on the other end to keep the acrylic from flexing.
2. Then I use sand paper at 120, 180, 220, 320 while spinning the material on the lathe to clean up the cut marks. 320 grit seems to be the magic number, after that I just polish it up on a homemade buffing wheel setup using white rouge. Sanding and buffing the acrylic brings the rod diameter down to about 0.39 inch - 0.395 inch for the finished diameter of the lens.
3. I then take the rod out of the lathe and sand the end square to get rid of the live center hole, then hand sand the end on a piece of 320 grit paper laying flat on the table (about 10 seconds), then polish the end on the buffing wheel. This polished end will be the bottom of the lens and it needs to be polished for the light to get through. It is easier to polish now on the end of the stick rather than after you cut it off!
4. Then I chuck the rod back into the lathe, just sticking the end out about an inch and neck the diameter down to fit the lens hole and just deep enough to seat the lens. It seems to vary on width and depth so I did each one individually. The diameter isn't cut much, just to about 0.38 inch or so. This gives a little overlap or shoulder on the top of the lens and it does look better. Kind of covers the top lip of the bezel and since the bezels vary in size diameter wise it is the best way to make them all the same as the shoulder is easy to cut and doesn't need to be finished.
5. I then cut the lens off at 0.405 inch long with a hack saw and epoxy it into the bezel with 5 minute epoxy being careful to only epoxy the perimeter inside the bezel. You don't want epoxy over the bottom of the lens as it will obscure light.
6. Let the epoxy set and then I shape the top with a vice mounted variable speed grinder with 320 grit sandpaper, then polish on the wheel. I screw the bezel onto a light housing so you can hold the damn thing while shaping and polishing.

I can turn one lens out in about 10 minutes with a piece of acrylic already turned down and polished minus the time it takes for the epoxy to dry. Turning down a piece of acrylic and polishing it takes about 15 minutes. You really only use about an inch or so of material for two lights! The lenses are not perfect but look good. They have a little bit of a wave in the bevel edge but they polish so well you can't tell. How many people are going to be looking that closely at some dash lights? The original lenses are round but I made these with a flat top and a slight bevel edge. I had a hard time making a uniformed round top so I just beveled the edges and left a flat top. I guess if somebody was so inclined they could make a jig over a sanding table and every lens would be very uniform. Only a crazy Guzzi fanatic would really know the difference! Watch, I'll be at a bike ride and somebody will comment on the lenses that they aren't original!

Alternative 2

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Thanks to Paul Linn who posted this information on the old Yahoo! Loopframe_Guzzi news group (which has now moved to Groups.io).

• Pioneer Breaker & Control Supply part number PLI-7T-RS-24A-12VDC (amber), 7 mm (not sure if that is the hole size or the bezel size)
• Pioneer Breaker & Control Supply part number PLI-7T-RS-24G-12VDC (green), 7 mm (not sure if that is the hole size or the bezel size)
• Pioneer Breaker & Control Supply part number PLI-7T-RS-24R-12VDC (red), 7 mm (not sure if that is the hole size or the bezel size)

Alternative 3

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Thanks to Mike Jones who posted this information on the old Yahoo! Loopframe_Guzzi news group (which has now moved to Groups.io).

• Radio Shack model 276-272 (orange LED), requires ⁹⁄₃₂ inch mounting hole
• Radio Shack model 276-271 (green LED), requires ⁹⁄₃₂ inch mounting hole
• Radio Shack model 276-270 (red LED), requires ⁹⁄₃₂ inch mounting hole

Thanks to John Allen who posted this information on the old Yahoo! Loopframe_Guzzi news group (which has now moved to Groups.io).

I wanted to share with everybody my fix for Ambassador police dash lights. I am missing 3 of the plastic tops on my bike. I'm working on crafting new acrylic tops for my original lights and am having some good success but that is another story. I ordered a set of Radio Shack LED's listed on Gregory Bender's web site as a suggestion by Mike Jones as an interim solution. What the led is missing is a bezel to hold them to the dash. I found an easy low cost solution that looks good. A ¹⁄₄ inch aluminum rivet nut fits perfectly, holds an o-ring, and the led fits inside perfectly. I've posted pictures of the finished aluminum bezel and led light assembly. The album is Ambassador dash light bezels.

The materials for each light are:

• One Radio shack Green LED #276-0271 (or orange or red) (USD $1.99)
• One ¹⁄₄ inch stainless steel washer (USD $0.20)
• One ¹⁄₄ inch × 20 Aluminum Rivet Nut (USD $0.52)
• One ⁵⁄₁₆ inch ID × ⁷⁄₁₆ inch OD rubber O-ring (USD $0.14)

Take the rivet nut and lightly sand the top to remove surface machining marks. I start with 320 grit and end at 800 grit. Next I use an aluminum polish and quickly polish the top and sides. Slide the O-ring over the rivet nut and stick it into the top of the dash. Mark the bottom of the rivet nut flush or a little shorter with the underside of the dash, pull it out and cut it off with a hack saw. Stick the led into the bezel, I'm going to seal the led to the bezel with a dab of silicone but in the pictures I haven't done it yet. Pop the assembly into the dash, put the stainless washer on the underside and tighten it down with the nut and washer that came with the led. Wire it in. I don't know if anyone has posted this type of solution before as I'm new to the loop group but hopefully it will help someone facing the same dilemma. Total cost of about USD $3.00 a light and a little effort. I like the look of aluminum on aluminum. I'm not sure how the led's will hold up to UV rays or long term use.

Thanks to Daniel Howe who sent me this information via e-mail. In Daniel's own words:

Not sure if I sent you this but thought it might help someone out if they have the same trouble I did. To convert the four idiot lights to LED I used red LED assemblies with built in resistors from Radio Shack part number 276-0270. They make them in blue, green and yellow if you like, my bike came from the factory with all red lights so I'm staying with that. You will also need six male spade connectors and two ring terminals for grounds and four flat washers painted black. Installation is pretty straight forward positive to positive, ground to ground, no modification to original harness required. Down side is they are not original, Up side is you will never have to worry about one burning out. Bright enough to see on a sunny day but won't blind you at night. The light LED is not on in the picture because I didn't have them turned on.

Alternative 4

Thanks to Mark Johnson who sent me this information via e-mail. In Mark's own words and photos:

I was looking to replace my badly damaged/missing instrument lights with something a little more modern and rugged but still mimicking the look of the original. After searching high and low I finally found the vintage look I was after, combined with LED technology in a waterproof package. Colors chosen are red, yellow, green and blue. White is also available. Discovered this particular rounded and raised style is very rare - so far I've found only one manufacturer that offers this design in the colors I needed and in the size required. Search for 10mm LED Metal Indicator Light Waterproof IP67 on the aliexpress website. The price is right too; I bought two sets just to be safe.

Instrument panel holes needed to be enlarged slightly to accomodate their 10 mm diameter. The photos do not do justice to the vivid and bright colors these lights provide, and I'm very pleased with the results. If you want LED lights but still want a vintage, pilot-light look these fit the bill.