Friday, July 24, 2020

Replacing a Royal Enfield speedometer

Original and replacement Royal Enfield speedometers.
Proof that my Royal Enfield Bullet has travelled more than 42,000 miles;
original speedometer/odometer, left, new (used) one as installed, right.
No trip odometer? No problem

Here is one tip for old Royal Enfield motorcycles I like a lot. Tim from New Zealand suggested an easy way to remember when to fill the gas tank: add gas every time the odometer rolls over 100 miles. You'll never have to try to memorize the mileage again.

I liked the advice, but there was no way I could use it. The odometer of my 1999 Royal Enfield Bullet stopped turning over at 42,480 miles.

I ignored the broken odometer for years, mostly because I was too proud of having racked up so many miles and so didn't want to give up my original speedometer/odometer.

But then a used one that looked similar came up on eBay and I bought it. It shows only 434 miles, which hopefully means it will work for many miles to come. We'll find out.

Interior view of Royal Enfield Bullet headlight nacelle.
View of original speedometer inside the nacelle, with
 cable detached, bracket removed and main light bulb pulled.
I am no mechanic, so it was my hope that I could unplug and remove the old speedo, install the new one and plug in the original bulbs and their wiring. From what I could see by peeking inside the motorcycle nacelle, behind the headlight, the original speedometer and the new one looked the same, although with possibly a different finish.

My original was stamped 12/98, obviously the date of manufacture, while the new one was stamped 06/2002. Obviously, the replacement one really is newer.

First step was to disconnect the speedometer cable.

Then I unplugged the main speedometer light bulb with its wiring. The warning bulbs for high beam, neutral and turn signal, though, are well back on the body of the speedometer and hard to reach. And the high-beam warning bulb was pinned beneath an edge of the bracket that holds the speedometer in place.

The bracket would have to come off anyway, to remove the speedo, so I left the three bulbs and their wiring in place for the moment and attacked the big nut holding the bracket. I found a 7/8-inch socket fit the big nut and was a big help getting it off.

The bracket, once off, was strangely shaped. I instantly forgot which way the bracket was supposed to go back on. Did it matter?

Yes. But no worries.

View of bottom side of replacement speedometer unit.
Here's how the bracket should fit. Note how neatly the half-round
hole fits around the plug for the high-beam bulb.
The key to getting it back on correctly is the half-circle notch in one side of the bracket. That notch — cleverly — allows service access to the high-beam warning bulb without removing the bracket!

The fact that the high-beam bulb had been pinned on mine indicated that the factory had put the bracket on backwards in 1998. I guess it doesn't matter that much.

Once the bracket was off it was easy to push the speedometer up from the bottom. But I could not push it out of the nacelle yet, because it was still held by the wiring of the warning bulbs. Unplugging them was made easier by the fact that the speedometer was loose, as I could get a screwdriver in to pry them out. They were in really tight.

With the speedometer finally completely out I could see there is a rubbery gasket that fits under the bezel of the speedometer and presumably keeps moisture from getting under the speedo into the nacelle. I would re-use this.

View of rubber gasket labelled with "D."
Letter "D" on bottom side of gasket tells you which part
of the rubber ring goes "Down" at the bottom of the speedometer.
This gasket is not the same width or thickness all the way around. The letter "D" on the bottom of the gasket marks the point that is supposed to be "Down" on installation. Very helpful.

Moment of truth! In goes the new speedometer. I installed the warning bulbs, bracket and speedometer light. The big nut on the bracket pulls the speedo down tight against the nacelle. (It's  a bit tricky getting the big nut tight without turning the speedo out of place in the nacelle. Note that the big nut has more grip on the bracket when oriented with its flattest side against the bracket.)

I switched on the ignition and watched the warning lights for turn signals, neutral and high beam.

The high-beam warning bulb didn't come on. I pulled the fitting out, removed the bulb and squinted at it; sure enough, the filament was broken. I salvaged a bulb from the unused wiring that came with my replacement speedometer. It worked! (These are 12-volt 2-watt bulbs if you need new ones.)

So, back on with the headlight and we're all ready for a test run, right?

Errr, no. I'd forgotten to reconnect the speedometer cable. Back off with the headlight and let's get that done.

UPDATE: The replacement speedometer/odometer works fine. Makes me wonder if I could disassemble the old one, rescue the odometer tumbler from it, and insert it into the working replacement? I'd love to be able to display the thousands of miles we've travelled.

4 comments:

  1. What is it about what to do with "well enough"?

    ReplyDelete
  2. Nice write up - I especially related to the disassembling everything again to reconnect the speedo cable. Hey - there's always time to do it twice, eh? ;-)

    ReplyDelete
  3. You could put a clear sticker on the odometer underneath the miles saying "+42,460"

    ReplyDelete
  4. ...or 142,460 as a conversation starter...heh heh heh ;-)

    ReplyDelete

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