My speedo's full of water...resolved with pictures.

[paddy]

Postscript: The seal is working well so far and just survived a decent overnight downpour. I did manage to avoid using the buttons for around 4 days to give the Gasket Goo a good change to set. I am thinking about adding a smaller diameter of glue-lined heatshrink to the PVC pipe. I would shrink it just above the holes to hold it in place, leaving the portion over the holes un-shrunk. It would be a bit like a splash jacket, but still allowing the pipe to breath. You can over-design these things though....

[Tony W]

I have one of these 'speedos' on my DR-Z400SM.

When I change to the 21" front wheel, the Km per Hour reading goes out about 15 percent. Does anyone know how to "get into" these to adjust, to compensate for tyre circumference.

(I am aware of the tripmeter distance compensation feature.)

[paddy]

I have one of these 'speedos' on my DR-Z400SM.

When I change to the 21" front wheel, the Km per Hour reading goes out about 15 percent. Does anyone know how to "get into" these to adjust, to compensate for tyre circumference.

(I am aware of the tripmeter distance compensation feature.)

Hey Tony,

There is a trip-meter distance compensation feature? Tell me more...

Hopefully the pictures above will give you a pretty good idea of how to get into it. There is a thin foam gasket that seals the back of the unit. Mine fell into several pieces, so you will probably need a plan b for re-sealing the unit if you are going to open it.

Everything that I am about to write is working under the assumption that your unit is internally identical to mine (which is on a 1997 DR250). On the back of the main PCB (printed circuit board) you will find a crystal (small elongated silver canister). Somewhere near the crystal you will see a small trim-cap (alterable capacitor). It is probably a reasonable assumption that the crystal and capacitor make up a reference oscillator that the pulses coming from the wheel hall effect sensor are compared to. If you can alter the frequency of the oscillator then you can alter the ratio between the two and therefore affect the speed reading for a given wheel revolutions per minute.

On my unit, the trim-cap was filled with epoxy. If you could somehow break that without destroying the cap then you might be able to adjust it. This has several large assumptions though. Firstly that you can break the epoxy without breaking the capacitor - which is very unlikely, second that you can drive the speedo at a fixed speed (maybe with a power tool) so that you can make a percentage based adjustment, and finally, that the oscillator isn't used for anything else within the trip computer - like the clock for instance (although this is extremely unlikely).

Personally I wouldn't bother; however, if I were going to bother, I would probably replace the cap altogether, or solder another one in parallel with it on the board and use that to make adjustments (indeed if you traced out the circuit, you could calculate the value required for a 14% decrease - which would translate into a 17% required increase in oscillator frequency - then you could simply solder a fixed value cap to the board).

Just for you reference, based on your wheel sizes (18"->21") you would expect your real speed to be 14% less than the value on the speedometer. For example, if the speedometer say 117 km/h then you will actually be travelling at 100 km/h (presuming that the unit was accurate for the 18" wheel).

If this stuff doesn't make sense to you, then I would leave it alone, you are probably going to break it. If it makes sense to you, then, like me, you have probably decided that it definitely isn't worth the effort. If I were you I would stick a GPS and the bike and use that.

Feel free to ask questions though and I will do my best to answer them...

Cheers,
Patrick

[Tony W]

Hey Tony,

There is a trip-meter distance compensation feature? Tell me more...

Hopefully the pictures above will give you a pretty good idea of how to get into it. There is a thin foam gasket that seals the back of the unit. Mine fell into several pieces, so you will probably need a plan b for re-sealing the unit if you are going to open it.

Everything that I am about to write is working under the assumption that your unit is internally identical to mine (which is on a 1997 DR250). On the back of the main PCB (printed circuit board) you will find a crystal (small elongated silver canister). Somewhere near the crystal you will see a small trim-cap (alterable capacitor). It is probably a reasonable assumption that the crystal and capacitor make up a reference oscillator that the pulses coming from the wheel hall effect sensor are compared to. If you can alter the frequency of the oscillator then you can alter the ratio between the two and therefore affect the speed reading for a given wheel revolutions per minute.

On my unit, the trim-cap was filled with epoxy. If you could somehow break that without destroying the cap then you might be able to adjust it. This has several large assumptions though. Firstly that you can break the epoxy without breaking the capacitor - which is very unlikely, second that you can drive the speedo at a fixed speed (maybe with a power tool) so that you can make a percentage based adjustment, and finally, that the oscillator isn't used for anything else within the trip computer - like the clock for instance (although this is extremely unlikely).

Personally I wouldn't bother; however, if I were going to bother, I would probably replace the cap altogether, or solder another one in parallel with it on the board and use that to make adjustments (indeed if you traced out the circuit, you could calculate the value required for a 14% decrease - which would translate into a 17% required increase in oscillator frequency - then you could simply solder a fixed value cap to the board).

Just for you reference, based on your wheel sizes (18"->21") you would expect your real speed to be 14% less than the value on the speedometer. For example, if the speedometer say 117 km/h then you will actually be travelling at 100 km/h (presuming that the unit was accurate for the 18" wheel).

If this stuff doesn't make sense to you, then I would leave it alone, you are probably going to break it. If it makes sense to you, then, like me, you have probably decided that it definitely isn't worth the effort. If I were you I would stick a GPS and the bike and use that.

Feel free to ask questions though and I will do my best to answer them...

Cheers,
Patrick

Thanks for the reply Paddy.

A mate had just bought a Vapor brand unit and it was easily adjustable by manipulating buttons on its face.
Wishful thinking made me make this hopeful enquiry !
Leaving well enough alone, is the answer in this case.
At least the tripmeters are adjustable.(actually 17-21)

Cheers, great effort.
Tony

[paddy]

Thanks for the reply Paddy.

A mate had just bought a Vapor brand unit and it was easily adjustable by manipulating buttons on its face.
Wishful thinking made me make this hopeful enquiry !
Leaving well enough alone, is the answer in this case.
At least the tripmeters are adjustable.(actually 17-21)

Cheers, great effort.
Tony

It is quite possible that there is an undocumented feature to change that. The problem is that I know nothing about the unit other than what I observed internally and what I found out at the following link:

http://www.thumpertalk.com/forum/arc.../t-352333.html

If you know any more I would be quite interested to know...for example, when you said the trip-meters are adjustable - did you just mean with the +/- buttons? It sounds like you are alluding to something a little more (which suggests that you would expect a similar functionality for the speedometer).

[Tony W]

It is quite possible that there is an undocumented feature to change that. The problem is that I know nothing about the unit other than what I observed internally and what I found out at the following link:

http://www.thumpertalk.com/forum/arc.../t-352333.html

If you know any more I would be quite interested to know...for example, when you said the trip-meters are adjustable - did you just mean with the +/- buttons? It sounds like you are alluding to something a little more (which suggests that you would expect a similar functionality for the speedometer).

Yes Paddy.
You can immediately alter your twin tripmeter + or - 30%.
I use this for compensating distance travelled when I change to the larger 21" wheel.

I use 115% for (17" to 21".)

[paddy]

Yes Paddy.
You can immediately alter your twin tripmeter + or - 30%.
I use this for compensating distance travelled when I change to the larger 21" wheel.

I use 115% for (17" to 21".)

Would you mind posting the process for making that adjustment for the benefit of anyone else that searches and finds this thread in the future?

[Tony W]

Would you mind posting the process for making that adjustment for the benefit of anyone else that searches and finds this thread in the future?

A pleasure.

The 4th button along is labelled TRIP/TIME.
Turn on ign key to enable power.
Press and hold down that button for 5 seconds.
One of the two trip displays will change: usually will read '100', as in 100%.
Then use the + or - button to adjust the amount of compensation.
The display has a change range of 70% to 130%.
When adjusted to your requirement, push TRIP/TIME to revert to normal display.

To readjust, repeat this procedure.

This procedure was taken from the handbook.

Cheers.