Tach Calibration

[emcclary]

Tell me if I'm nuts but I swear I read a thread sometime ago saying the tachs can be checked via Big Dog software for accuracy in calibration. I just took my K9 in for the 2500 mile service and asked them to check it and they told me there was no such thing. I feel my tach reads 200-300 rpm lower than what it shows based on my printout from the dealer. Also what is considered redline for rev limiter hit. I show 5 but only 2 seconds over 5000 rpm.

 

[Raywood]

Don't know about the tach but know you can calibrate the speedo.

The rev hits are surprising as you can see in my ignition print out that I have 6 hits and very few seconds over 5000 rpm. But I am sure that it records a hit at 6000 rpm.

What makes you feel it not reading accurately?

 

[Byrddogg]

how do you calibrate the speedo?

 

[emcclary]

I know where I have spent most of my riding time the last 2000 miles and it was between 2500 and 3500 rpms while the dealer printout shows 2000-3000 was the sweet spot. On the rev limiter hits I show 1 sec at 5100 rpm 1 sec at 5200 rpm and zero from there up to the 6400 rpm limit on the chart. the chart says i hit it 5 times.

 

[Raywood]

how do you calibrate the speedo?

In the service manual there is a process you follow to re-calibrate it. I've never tried cause I never thought mine was off.
If you need the procedure I can photograph it and send it to you.

Later,
Ray

 

[emcclary]

Blitz when I bought the bike it had zero hits they gave me the original printout. I'll check the other site for info as well maybe I read about it there. With digital tahc I would think you could be off as much as 500 rpms since each light only responds once you hit the lower limit supposively. From 3000-3499 you should only see the 3000 light lit.

 

[Raywood]

Blitz when I bought the bike it had zero hits they gave me the original printout. I'll check the other site for info as well maybe I read about it there. With digital tahc I would think you could be off as much as 500 rpms since each light only responds once you hit the lower limit supposively. From 3000-3499 you should only see the 3000 light lit.

I don't know how Autometer does it but I would think that the 2000 rpm light would have a range of say 1750 to 2250 then 2250 to 2750 for the 2500 rpm light which is 500 rpm increments. But who knows.

 

[emcclary]

no probs Blitz thought that might be the case. I just want to be able to know for saure where I am riding. I mean technically its better for me if big dog thinks I'm running 4500 instead of 5000 but I dont want them to claim I am luggin the bike either. Still would like to know how the rev hits come in at five though.

 

[Raywood]

With over 42,000 now on mine and plenty of warranty issues BDM has never questioned my 6 hits. I think is shows when you see that there is hardly any time (seconds) above 4500 rpm. No telling how the Thunderheart ignitions record those hits. I can tell you I've never seen a red light on mine that comes on at 5500 let alone a yellow light.

I wouldn't worry about it to much,
Ray

 

[P8RIOT]

I don't know how Autometer does it but I would think that the 2000 rpm light would have a range of say 1750 to 2250 then 2250 to 2750 for the 2500 rpm light which is 500 rpm increments. But who knows.

...may be a good question for the Ohmster.

 

[Ohmster]

The tach ring cannot be calibrated and Blitz is correct on the 500 rpm variance. The tach ring led's illuminate approximately on a plus or minus 250 rpms from the rpm they represent. Keep in mind the tach ring is only a reference of the actual rpm the engine is at. As for any rev hits the ignition module logs, it gets its rpm information from the crank sensor, not the tach ring. The tach ring is an output only from the module and any failures that could ever occur to it that would cause any led lights to max out are not logged by the module.

 

[P8RIOT]

Great answer, Ohmster - we've been "arguing" about how that really works for a long time now. :up:

 

[bdmridgeback]

I have never seen a red light on my tach, I have only seen the yellow a couple times.

 

[Gas Man]

I've saw red...when I turn off the key.