Odometer & Trip meter not advancing

Today I repaired my "Reaganometer" as BigFitz likes to call it. I had to combine two gear and cable units to make one usable unit. The gear in one was caked with rust, and the cable in the nice, greasy one was snapped off at the end.

I took the XJ for a spin, and the speedo and tach work great but neither of the odo's advance at all. I spun the trip meter to "333" just to see if I could get a gear to catch or something but no soap.

The odo's aren't electrically driven are they? Has anyone ever replaced a gear in these units? The bike is an '82 XJ 750 Seca.

I did consult the archives, but 99% of the entries only concern the trip meter, and there were nearly no solutions. Surely someone out there has dealt with this.

Thanks.

 

Ok, first, did the trip meter and odometer work before you combined the two units or are you not sure? The reason I ask is because the 750's are notorious for damaged speedos (which include the trip meter and odometer). What happens is that in those unfortunate instances when the bike is tipped over on the side and it happens to be the left side, the impact inevitably pushes the gears in the speedo unit together so that they wear out prematurely. The unit is assembled as part of the stamping process so that to disassemble it is not a task for the average bike owner. It was not designed to be serviced - ever! There are no adjustments that can be made and even if you were to successfully diassemble the unit, you would be hard pressed to find replacement gears (chacal - if you are reading this what are your thoughts on replacement gears? - if you can find them I would be willing to offer my services to install them as I have a machine shop). So what I would do is keep my eye open on ebay but make sure you press the seller to give you a definite answer as to whether it is a WORKING unit. I have bought THREE units off ebay that were all damaged in the same way as I have described to you and had several other sellers pull their listings when I insisted that they check the unit for damage to the corner of the unit before I bid. Best wishes and I hope you find a working unit. I have found a couple of working units that sold for around $60 but they are often closer to $100.

 

I have no idea if they worked before I repaired the gear drive mechanism. This bike has led a rough life of neglect and hard riding. I know for a fact that it has been dropped and/or layed down. I know it's landed on it's right side, but I'm not sure if it also landed on the left at some point.

I'll do what you said and keep an eye out on ebay. Bummer too, there were several sets that sold recently but I didn't bid because I didn't think anything was wrong with mine and I simply don't have the space to accumulate a spare, disassembled XJ 750.

Thanks for the info.

 

sushi
Sure thing. One more thing though, it might be worth a peek inside the case before you abandon your current unit. You might notice something that is easily correctable. When you split your case in half you can pull the speedo unit out of the case and get a better idea of its function. If you still have the end of the broken speedo cable you can chuck it in your hand drill and spin the speedo while you're holding it to watch the gears turning and then you can pin point where the problem exists and whether it is something you want to tackle. You have to run the drill in reverse for the speedo to function properly. Your drill probably won't have enough RPM's to get the speedo above 35 but it will be enough to see the gears meshing and turning. I know it is a bit of a pain in the neck to pull the instrument cluster on these things but you may find that yours is an easy fix. If you don't mind keep us posted so that we can all learn something.

 

Does this help?

This is a typical Yamaha mechanical speedometer assembly odometer drive. The TRIP ODO on this one has been removed, it is normally attached at the point indicated by the blue arrow.

Speedometer head A spinning in the direction of the green arrow, drives countershaft B which in turn drives the odometer drive shaft C which turns the odometer gear D and drives the (missing) trip odometer via gear E



The bolt on the left is just to prop it up for the pic.

 

mirco nice one abt the hand drill - you live n u learn (I never knew abt that)
can i try that on my old tach just to find out why it stopped?

 

Yeah it helps. As with my carbs, I'll try to acquire a spare unit to dissect instead of making my otherwise great motorcycle non-functional.

 

bf,
Awesome picture and diagramming! What is that unit off of? It is identical to the 750 Seca except the Seca does not use nylon gears at "A" and "E".

shangovi,
Unfortunately the same method will not work with the tach because the tach is electrical actuated and not mechanically driven.

sushi,
It's the "A" and "B" gears that are the normal culprits when the bike is tipped over. Misalignment of the worm gear "A" to the rack gear "B" is where you have issues.

If you will notice, there is no way to disassemble the unit without bending the stamped housing so as to remove either rack gear "B" or worm gear "A". Since fitz has provided us with such a crystal clear photo (thanks fitz) I will explain to you that the way I disassembled mine was to carefully drill the post on the right side of the rack gear "B" where it goes through the wall of the stamped housing. Then I was able to remove the rack gear. Once the rack gear was removed, I was able to remove the worm gear. However, the worm gear is mounted as an assembly that is swaged into the housing. Once you grind off the swaging that holds it in the housing you will have to be prepared to come up with another method of securing it to the housing since there will not be sufficient material left to re-swage it to the housing. Brazing or silver soldering would be preferable because even the strongest two-part epoxy will probably not be able to hold up to the torque and tension from the twisting motion of the speedo cable.

If you get that far, and you know someone with a machine shop, they can manufacture new gears for. However, the cost will probably be more than what you can buy a set for off of ebay unless they owe you a favor. If they do owe you a favor, and you decide to go ahead with this project, keep in mind that the worm gear is left handed. If they make you a right handed gear - even if it has the correct pitch - it will run BACKWARDS. Please don't ask me how I know!

I will be glad to answer any other questions as best as I can. I know that this makes synching your carbs sound like a walk in the park but it can be done. Those of us who enjoy riding these vintage metric bikes tend to be a patient and persevering lot (read - CHEAP).

Best wishes.

 

That one is from an '81-'83 Seca 550. They're virtually all the same, some moreso than others. By that I mean they're all the same basic shape, most even use the same frame but there are SUBTLE differences.

The one in the pic got its trip odometer removed in the course of my efforts to replace the 85mph unit with a 150mph unit, which were successful. The trip odo transplant wasn't but that's a whole different story.

Speedo swaps are very do-able, within certain constraints. How I managed this is still in the write-up stage:

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Damn that looks nice.