70/75 mph all day long

[Adamastor]

Hi there, i was willing to try the lamp test but discovered that in portugal our electric grid works at 50Hz (not 60hz)... I guess it wont work at 1200/2400/3600rpm... Can you help me out with the formula to know what results should I get with 50hz?

Many thanks...

Sergio

[Adamastor]

Got it!

50Hz check point are at 1500 rpm and 3000 rpm (and so on).

It is really hard to do a test with a lot of precision, because I find it very very difficult to fix the throttle at a specific rpm (it is too sensitive and a little movement is always too much), but with the help of my father I think I got these results:
Where is was supposed to be at 1500rpm it showed 1700 and at 3000 rpm the tachometer showed 3500rpm.

If I could find what screw to turn to fix this would be great... at the same time I am not sure If this test is that good..

What would you do? (there's always the option to buy an ebay tachometer... but that's the most expensive solution, ain't it?)

[Barry]

at the same time I am not sure If this test is that good..

If this type of test works at all then it's very unlikely to be wrong as the Electricity grid frequency is usually very accurately controlled. When I was involved sometime back in electricity distribution and synchronizing generators to the grid. the magnitude of error you have found would have been unthinkable as there was a statutory requirement to keep within 50 Hz + or - 1% and in practice it was always better than that. So I would trust your result.

[Adamastor]

Thanks Barry, but the only thing that can be wrong on the equation are my eyes and/or the time it that takes for my father to do the tachometer readings I believe the 50Hz should be fine ...

I must try to find the adjustment bolt on the tachometer... Unfortunately I believe it might be inside the case...

[Barry]

Adamastor

I can't help with identifying the location of the adjustment but I have opened up my Tacho before to insert a small bag of desiccant and it wasn't at all difficult. I think there are just a few screws securing the rear cover.

Whatever you do be methodical and mark or photograph anything you try prior to adjustment. It's likely to be small potentiometer.

And if you succeed we will be wanting you to post a photographic record of the correct adjuster.

[Adamastor]

Adamastor

I can't help with identifying the location of the adjustment but I have opened up my Tacho before to insert a small bag of desiccant and it wasn't at all difficult. I think there are just a few screws securing the rear cover.

Whatever you do be methodical and mark or photograph anything you try prior to adjustment. It's likely to be small potentiometer.

And if you succeed we will be wanting you to post a photographic record of the correct adjuster.

Will do that, Barry, I think I might have some time to study it tommorow and will take my digital camera to my parents house (where the R65 is)...

Regards

Sergio

[Adamastor]

HI there,

It was really easy to find the adjusting potentiometer, it is the only one inside the case
I took some photos anyway...


Unscrew these 3 screws...


Inside you find this little potentiometer... that's the one you have to adjust...


A little adjustment does a lot, so take it easy.. counter-clockwise drops the needle, clockwise raises it (I had to rotate counter-clockwise just a little bit).

I just had the chance to go for a small ride and at 80 (50mph) km/h on 5th I was at 3250rpm. It looks like it spot on, but will have to test it further at 100 km/h and 120 km/h

While I was inside, I also left a little desiccant bag so hopefully I get no moisture inside the tachometer...  8-)

[Barry]

Glad you solved the problem Adamastor and excellent pictures which should be a good record for anyone else to adjust their tachometer.

That potentiometer looks to have had a spot of yellow paint on it to help stop vibration from changing the setting. Maybe it had moved a little anyway.

[nhmaf]

Thanks for posting up the pics - I agree this would be a good set of pics/info to include in our tech section wiki!

[Adamastor]

Glad you solved the problem Adamastor and excellent pictures which should be a good record for anyone else to adjust their tachometer.

That potentiometer looks to have had a spot of yellow paint on it to help stop vibration from changing the setting. Maybe it had moved a little anyway.

Hi and thanks, Barry,

I wonder If I should have used also a small drop of paint so it woudnt move...

Sergio

[Barry]

I wonder If I should have used also a small drop of paint so it woudnt move...

Sergio

Ideally yes but I would live with it for a while to make sure you are happy with the calibration and even if it does move in the mean time at least you Know how to recalibrate it.

By the way the little pack of desiccant proved to be only a short term
fix in my tacho. I've been meaning to take it off and dry it out thoroughly before resealing.