Rev Counter KOSO III GP Style

I want to fit it on my PX150E but of course no battery, does anyone already try to fit one and what about the modifications?

Rev Counter KOSO III GP Style
Ø=48mm, 15.000 rpm
carbon/black faceplate
Art.-No. KODM55

Sure it helps, thanks a lot, you think the best solution is 3?

Hi mikkke, number 3 is probably the cheapest way to go, I went for number 2 because I also ran a small alarm aswell. Dry cell rechargeable batteries are so small and cheap to buy and as a rev counter draws such a low current I think it will be the best option.


Do you think those ones are ok and would be ok for the job?

Voltage regulator PIAGGIO PK
50XL HP/Rush/Ape FL3
P125-150X/P200E 1. series
with battery/indicators, 5 con
Art.-no. 21806000

Voltage regulator PIAGGIO/
GILERA, 12V 34/36W, 5 conn.
Vespa PK S/XL/ETS/P125-150X/
P200E incl. battery/PX EFL e-s
Art.-no. 29401650

Voltage regulator RMS PK50XL
HP/Rush/Spe FL3/
P125-150X/P200E 1° series
with battery/indicators, 5 con
Art.-no. 85150000

Hi mikkke and all , i’ve been in the same situation myself with my T5 also no bloody battery. 3 choices were given to me by others.

  1. was to use a thing called a bridge rectifier it turns ac into dc this can be mounted next to your regulator from wich it would get its power feed. It is a small square thing with 4 termanals on it , ac + and ac - dc + and dc -

ac+ comes from the power outlet wire on your regulator
ac- comes from the chasiss of your scooter

dc+ goes on to the + on your rev counter
dc- goes on to the - on the rev counter

this did seem to work very well but the voltage from the vespa regulator varies a lot 9v up to 20v , this because the regulator does not have to be that good on a vespa with out a battery.
rectifiers from maplins electronics .50p 1 euro.
2. was to fit a battery, I got a very small one from a motorcycle shop and put it under the seat, wired throu a PK 50-125 regulator. this regulator sits in the same place as your old one and very easy to wire up. It has the same outlets as the other one but an extra one for the battery. Then run the wires to the rev counter from the battery.

  1. was to use a rechargeable battery , and charge it when it went flat , which would a weekly/monthy thing to do not daily. These batterys are from Maplins electonics shop, very small and very cheep.

hope this helps and not confuses.


Thanks, quite clear now

See ya![:bounce:] [:bounce:]

I received the regulator (Art. n°21806000) yesterday, what about the battery, which kind can I buy is a 12v 5,5Ah ok or do I need more??

Hi Mark;

I don’t really mind for the price right now, I want the better way and more reliable way to use it and to work with it.

Hi mikkke, the one I used was the 29401650

the terminals as follows the

A is the old G

A is the old G

G is to go to the ignition key if you have a two wire switch back, this was used to stop the battery flattening when the scooter is not in use. However you do not need to use this as I believe the regulator has a blocking diode in it. But, if you want to use it then puchase a two wire switch and run a wire through the scooter to the switch from the G terminal.

B+ goes to the + on the battery

the last terminal is the earth/ battery - all earths share the same path now as a capacitor inside the regulator keep the ac/dc negatives apart.