Honda RPM gage signal voltage

[tywiesz]

Hi, my a honda rpm gage shows 3200 on WOT , 450 idling, I tried to toggle that switch for cylinder selection, works only on setting 1, others like 200, 100 at idle. signal voltage from honda 4 stroke 90hp is 0.65- 0.7 volt. If 1volt = 1000 rpms than the motor is running around 650-700 rpms, Broken gage?
cheers
T

 

[roscoe]

Does your Honda Tachometer read voltage changes?

 

[tywiesz]

Hi, and thank you for asking, yes, it responds to the throttle, 1/2 open throttle 1600, at wot 3200 rpms showing, seems like half of sort. I wish i know what's the signal voltage to the rpm from the motor. grrr
T

 

[roscoe]

I believe your tach only responds to the number of pulses produced by the stator. So as rpm increase, pulses increase, tachometer responds.

Yes voltage may change, and amps will increase as rpm increase, but its the pulses that are counted.

 

[tywiesz]

ok, good point, you are saying it is not analog but digital, I was reading otherwise. Tomorrow I'm gona take a full spec of voltage ad frequencies going to the gage using an oscilloscope on a full scale of the throttle.
cheers
T

 

[tywiesz]

I believe your tach only responds to the number of pulses produced by the stator. So as rpm increase, pulses increase, tachometer responds.

Yes voltage may change, and amps will increase as rpm increase, but its the pulses that are counted.

suppose my rpm gage is digital, so there are two possibilities than:
1. pulses from the motor not correct or
2, the rpm gage electronics/counter is ar fault
T

 

[tywiesz]

ok, good point, you are saying it is not analog but digital, I was reading otherwise. Tomorrow I'm gona take a full spec of voltage ad frequencies going to the gage using an oscilloscope on a full scale of the throttle.
cheers
T

Hi,
all parameters of incoming signal at diff. rpm's didn't make any sense so I borrowed used tacho and installed, Well it worked, idle 1200 rpms, I can throttle up it goes 4000 rpm in neutral didn't wanted to do more, tomorrow test on water.
cheers
T

 

[sam am I]

Faria says your 4 stroke 90 has 4 poles, if this is accurate then I believe your gauge's setting dial should be set to "4". "switch on the back of the tachometer to the correct position to match the number of poles in the alternator"

Perhaps your gauge is messed up esp since you said you've tried that setting and it was wrong there too?

 

[tywiesz]

Hi,
all parameters of incoming signal at diff. rpm's didn't make any sense so I borrowed used tacho and installed, Well it worked, idle 1200 rpms, I can throttle up it goes 4000 rpm in neutral didn't wanted to do more, tomorrow test on water. Btw, setting on 1 for 4 poles on this particular tacho. Old one was originally set to 4.
cheers
T