Topic: Speedometer and Rev Counters

[fishman_Phil]

Hi all ... just been checking my spare parts to see what is salvagable/usable for my CB350F Bikes and found this box of Speedo and Rev counters(see Pic). Also in the box which measures 350x350x240mm was a headlamp and wireloom. A total of 27 stainless bases were found for the guages in there. For the CB350F only 4 Rev and 3 Speedo guages were found.
The rest I imagine are off other Honda 4's. All with angled cable connectors. They had readings up to 180kph and 1 at 185kph. The rev counters had readings of 9200-11000. What would these be off?
My CB350F and the spares I have all read in mph up to 110 and the rev counters 10000-11000.
Cheers ... Phil in NZ

[FunJimmy]

We bit of a collection Phil?

I’ve got a few of tachs for my 550 project and they all get slightly different readings when connected. I haven’t opened any of them up yet, but it looks like you have.
Could you describe or post pictures of how they work mechanically? There must be some type of clutch device internally that prevents the needle from spinning around. Does cleaning and servicing the internals have an effect on the accuracy of the tach and is there a recommendation for this procedure?

Anyone calibrate a tach lately? How would it be done?

Thanks
Jimmy

[troppo]

We bit of a collection Phil?

I’ve got a few of tachs for my 550 project and they all get slightly different readings when connected. I haven’t opened any of them up yet, but it looks like you have.
Could you describe or post pictures of how they work mechanically? There must be some type of clutch device internally that prevents the needle from spinning around. Does cleaning and servicing the internals have an effect on the accuracy of the tach and is there a recommendation for this procedure?

Anyone calibrate a tach lately? How would it be done?

Thanks
Jimmy

G`day jimmy
I`ve just made one working tack out of two non working ones, cant say how acurate it is but they were both the right tachs for my 750 (i hope lol)
the needle is actually prevented form spinning around by a spring, and it is not physically attached to the drive cable, that turns a small wheel that has a couple of strong magnets on its head and is surrounded by a bell of steel that is attached to the needle.
If i remember i will post a couple of pics tomorrow for you showing the internals.
Cheers mate
Troppo

[troppo]

OK, heres the pics, damned digital camera doesnt like me.......

the pics are of the remnants of two tachs, this is the bad bits that are left over from the rebuild

first one shows the internal of a cb750 tach, the red arrow points to the return spring attached to the axle shaft for the needle, looking at it i cant work out why it wasnt working lol


This shows the inside of the body, still cant figure out why it wasnt working


This one shows the drive section of the whole thing, the magnets are attached to the head, the image isnt too sharp, but in the centre of the head its badly worn.


And finally this shows the "head" section of the tach, the red arrow shows the gouged section of the axle shaft mount that was causing the tach to jam up and jump around, clearly something had caused the drive head to force its way up and start chewing the alloy part up


Hope these might help someone out with tach problems, or just give a laugh
cheers
troppo

[FunJimmy]

Hope these might help someone out with tach problems, or just give a laugh

troppo

Thanks for taking the time to explain things and post oictures. That helps alot.
I have two tachs and both have different readings. Cleaning and re-lubing is propably all that's needed.

Jimmy