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RD350LC Speedometer
Conversion or Replacement

Is your LC speedometer in km/h but you need it to be in mph or vs. versa or is your speedometer not working, faded, has a melted face or otherwise is in need of replacement?  Have you been unable find a replacement or they are simply too expensive?  Well then is is for you, here you will see how easy it is to replace the speedometer head unit with that from another Yamaha model.  Depending on the country you live in, there are several other models from about 1977 to 1982 that have the same face style which you can use in the LC's plastic case.  In the US the choices are limited slightly due to the fact that in 1980 all US spec models adopted the federally mandated 85mph speedometers with the mandatory 55mph national speed limit highlighted in red.  In other countries you will have a full range of choices, basically if it has the same style of face then you can use it, you only need to decide if want a 110, 120, 140 or 160mph top speed.  In the case of metric speedometers the choices should be 180, 200, 220 or 240 but again if the face is the same style then it will be a good choice, follow along to see how to do it.
The following are some of the models which will make a good donor, it is not however a comprehensive listing.
  • XS750
  • XS850
  •  XS1100
  •  XJ650 (SECA in the US)
  • SR500
  • RD400F

Case swaps must be from plastic to plastic or metal to metal, internals are not the same.
     
  Here we have a broken, water damaged wrecking yard POS LC Speedometer.  Useless right?  Not so fast, the internal parts and glass are basically junk but the plastic case is undamaged and while the ring is in need of refinishing it is otherwise useable.   Here we have a $10.73 eBay speedometer from a 79 XS750 in very nice shape.  Even though it's the right size, style,shape and the mounting lugs are the same distance apart, there's no way to fix it to the LC upper cover.  
     
  Here's what makes the LC speedometer unique to other Yamaha models.  There are two of these tabs, one at 6 o'clock and another at about 10 o' clock which hold it to the upper cover with two small sheet metal screws.  The tach also has these with the tabs reversed left to right.   Here's the tools needed.  A number 2 Phillips screwdriver, dental pick, duck billed pliers and something to re-crimp the ring. I used this screwdriver with a double ended ¼" ends as it has a large handle for a good grip when pressing the ring back down.  
     
  First remove the trip meter knob, rotate it clockwise to remove and counterclockwise to install.  At first it may seem as though it doesn't want to come off but keep turning and it will eventually.   Next remove the night time illumination harness, these simply pull out.  Save the one from the LC for reinstallation if you are swapping one from another model or use the better of the two if you have two LC speedometers.  
     
 

The black rectangular plug with a black wire and a white w/green tracer is the reed switch.  This calculates time and distance for the self cancelling signals.  Not all models will have this.  If the case you will use has one leave it in place, if not remove it by gently prying upward and glue it in the LC's case, you will need to fit the wires into the LC's plug to do so.

  

Now we come to the opening the case.  The important part about these pliers is the finely serrated jaws which allow them to grip the edge of the ring securely and bend it back.

  
     
 

First put some tape around the metal ring if you intend to reuse it.  Then place the pliers nearly vertical so one side of the jaws are on the crimped edge of the ring and the other is against the side where you have taped, rotate the pliers back and pull the crimped edge of the ring up and away from the case.  Go slowly, don't try pulling it away all at once.

  

When the crimped edge is about vertical all the way around you should be able to lift off metal ring and glass from the plastic case.  The speedometer head unit is attached to the case so it won't fall out.

  
     
 

Now turn the case over (careful not to damage the needle) and remove the two #2 Philips screws holding the case and head unit together.

  

Now you can separate the case from the head unit.

  
     
 

Here we see the head unit and the case after separation.

  

This is the inside view of the LC's case.  Give it a good wash, the dishwasher works here, top rack only please. Make sure that the metal shroud didn't come loose while you worked on it and that everything is thoroughly dry, you don't want any moisture in there.

  
     
 

Here's the LC case all washed up and ready to accept the new head unit.

  

Here is the metal ring, glass and rubber/plastic rings which support it.  The order from inside to outside is a flat rubber ring, flat (mostly) plastic ring, rubber ring with a groove which the glass sits in and the outer metal ring.

  
     
 

First remove the flat rubber ring.  Next is a thin plastic ring with a stepped edge on one side and a tapered edge on the other.  The tapered side goes towards the glass.

  

Now remove the rubber ring that holds the glass, careful, it may stick in there and it's only 2mm thick so don't crack it. 

 
     
 

Note that the LC ring has two flat areas that aren't crimped.  These go around the supports for the fixing tabs.  If you use the ring from the donor bike be sure the ring is vertical or pointing in slightly before fitting as it will be difficult to push it against the case when fitted.

  

Now, while the LC case dry's, repeat the process on the donor and you will be left with this.  The basic speedometer head and face unit.  This part is mechanically identical the the LC other than mph/km/h differences.

  
     
 

Insert the donor speedometer head into the LC's  plastic case.

  

Point the cable drive into the hole in the middle and line up the two holes for the screws and reinsert them.

  
     
 

After thoroughly cleaning the rings and glass first fit the glass with the rubber ring into the metal case.  The curved part of the rubber faces out.

  

Now fit the plastic ring so the tapered edge is against the glass and the stepped side facing you.

  
     
 

Lastly put on the flat rubber ring

  

Check once more that the glass is clean, no grubby fingerprints or lint from cleaning it......this is your last chance, you don't want to open it twice right?

  
     
 

Now with a large flat tool such as this slowly work your way around the ring PUSHING it back down, don't be temped to hit it......it's glass and plastic so it can break.  Again, don't try to do it all at once, make at least two passes around the ring.

  

Here's how it should look when done, you can see some evidence of being opened but not a huge amount and once fitted with the covers you will never know the difference.

  

 

 
 

 
 

DONE!

  

Good Luck
 
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