Speedo Stopping And Starting?

ok ... 5th gen with 50 000 kms , original electrics.

Went out for a ride and noticed my speedo at zero, then bouncing to what seemed to be the correct speed , then back to zero.

After some playing around I noticed that it was only correct when accelerating and fell to zero the rest of the time.

Before everyone goes all RR on me...

while at speed if I pull in the clutch and rev the engine the speedo will stay at zero all day. Again it only works under load when accelerating. Any ideas?

I also removed the sensor on the sprocket and the plastic nut seems to be ok. how can I test the sensor itself?

ok ... 5th gen with 50 000 kms , original electrics.
Went out for a ride and noticed my speedo at zero, then bouncing to what seemed to be the correct speed , then back to zero.
After some playing around I noticed that it was only correct when accelerating and fell to zero the rest of the time.
 
Before everyone goes all RR on me...
while at speed if I pull in the clutch and rev the engine the speedo will stay at zero all day. Again it only works under load when accelerating. Any ideas?
I also removed the sensor on the sprocket and the plastic nut seems to be ok. how can I test the sensor itself?

The test procedure is in the service manual. I had the same issue and it turned out to be the sensor and not the plastic nut. The procedure requires a volt meter. If you haven't already done so, down load the manual from the downloads section.

thanks Duc.. I guess when all else fails, read the manual!

I was also thinking of hooking it up to a drill and seeing what happens, although that may not work while sitting in my garage in neutral.

I'd still like to know why it works under acceleration?

thanks Duc.. I guess when all else fails, read the manual!
I was also thinking of hooking it up to a drill and seeing what happens, although that may not work while sitting in my garage in neutral.
I'd still like to know why it works under acceleration?

The drill trick would work as long as voltage is running through the sensor. If you remove it from the bike, you can still put voltage through it and read the pulses coming from it with a meter. I believe it is a +/- 5 volt. I know I did a post about my venture with this but I'm being a little lazy at the moment to go search for it.

thanks again.

I'll look into it tonight

My 98 is doing the exact same thing right now. The plastic nut looks good so we're probably stuck with the sensor.

I haven't done the test procedure and just continue to ride it because I don't care what the speedo says anyway.  :wheel:

When a mechanic (who was new to VFRs) at my Honda dealer was replacing my chain and sprockets it was revealed that the old front sprocket was wider that oem. But no one, including myself, knew the significance of that. On the way to SumSum3 last summer my speedo quit working. Hispanic Slammer correctly diagnosed the problem as the female nut that engages the speedo sensor was not engaging the male part. By sliding the female nut on it's shaft towards the sensor, speed monitoring was restored. Thanks HS.

Hopefully your problem is that simple; part numbers 18 and 20, located at the front sprocket, are the culprits:

[image: MBG4F0200A.gif]

thanks Duc.. I guess when all else fails, read the manual!
I was also thinking of hooking it up to a drill and seeing what happens, although that may not work while sitting in my garage in neutral.
I'd still like to know why it works under acceleration?

The drill trick would work as long as voltage is running through the sensor. If you remove it from the bike, you can still put voltage through it and read the pulses coming from it with a meter. I believe it is a +/- 5 volt. I know I did a post about my venture with this but I'm being a little lazy at the moment to go search for it.

It's 12v.  Its power comes trom the tail light circuit.

Ciao,

I had a similar problem with the white plastic adaptor for the speedo drive. Someone (not me) had failed to align it with the sprocket nut when tightening the mounting bolts, and the end of the sensor shaft had pushed through the stop on the plastic nut, so the nut was sitting further onto the shaft than it should, and not making good contact with the sprocket nut. Buy yourself  a new adaptor, they're only a few dollars.

ok somehow the plastic nut has moved on the shaft. Its not engaging with the sprocket nut.

Can anyone measure the length of the plastic and the distance between it and the sensor body?

Terry .What is the adaptor, the plastic nut ?