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jroberts5407
03-21-2004, 04:09 PM
I am having a problem implementing an aftermarket tachometer on my SV track bike. I have tried two different tachs and so far I have not been able to fix it.

The tachometer reads correctly at idle but when the engine is revved, especially at the upper RPM range, the needle is very erratic, and wavers widely up and down. For example at 9000 rpm the needle is waving back and forth from 4,000-14,000 RPM.

I have double-checked all of the wiring and voltages and they are all OK. I have tried two different tachometers, a Sunpro (for car use) and a Daytona (made specifically for motorcycles, LP sells them). The Sunpro hooked up to the negative side of the coil for the trigger. The Daytona uses an inductive pick-up wire around the spark plug. I have tried electrical noise filters on the 12V side and even tried running the Daytona from a seperate battery. Same problem.

Anyone got any ideas on how to fix this? I really need to get a working tachometer setup for racing. /ubbthreads/images/%%GRAEMLIN_URL%%/confused.gif

jroberts5407
03-21-2004, 04:09 PM
I am having a problem implementing an aftermarket tachometer on my SV track bike. I have tried two different tachs and so far I have not been able to fix it.

The tachometer reads correctly at idle but when the engine is revved, especially at the upper RPM range, the needle is very erratic, and wavers widely up and down. For example at 9000 rpm the needle is waving back and forth from 4,000-14,000 RPM.

I have double-checked all of the wiring and voltages and they are all OK. I have tried two different tachometers, a Sunpro (for car use) and a Daytona (made specifically for motorcycles, LP sells them). The Sunpro hooked up to the negative side of the coil for the trigger. The Daytona uses an inductive pick-up wire around the spark plug. I have tried electrical noise filters on the 12V side and even tried running the Daytona from a seperate battery. Same problem.

Anyone got any ideas on how to fix this? I really need to get a working tachometer setup for racing. /ubbthreads/images/%%GRAEMLIN_URL%%/confused.gif

CYCLE 1
03-21-2004, 05:17 PM
John, this is not unusual, most aftermarket
tachs are junk!. SPA makes a very nice
Tach. I would purchase the micron lap timer
with built in tach kinda like a two for one
mine works well.

CYCLE 1
03-21-2004, 05:17 PM
John, this is not unusual, most aftermarket
tachs are junk!. SPA makes a very nice
Tach. I would purchase the micron lap timer
with built in tach kinda like a two for one
mine works well.

jroberts5407
03-21-2004, 05:55 PM
Thanks for the info Scott. And yes you are right the Sunpro is definitely a cheap tachometer, $45 new on Ebay. At least I did not pay full retail. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

I took a very serious look at a Mychron 3 series unit before I bought this tachometer. Are you using one of the Mychron 2 units or one of the Mychron 3 digital dashboard units?

jroberts5407
03-21-2004, 05:55 PM
Thanks for the info Scott. And yes you are right the Sunpro is definitely a cheap tachometer, $45 new on Ebay. At least I did not pay full retail. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

I took a very serious look at a Mychron 3 series unit before I bought this tachometer. Are you using one of the Mychron 2 units or one of the Mychron 3 digital dashboard units?

CYCLE 1
03-21-2004, 06:18 PM
Not sure what series it is but is
the smaller one with a digital display.

On a personal note I generally only use my
tach to check gearing especially at TWS
I have so much seat time on a SV and the
limiter is so soft that I dont rely on it
much, and very seldom hit the limiter.
/ubbthreads/images/%%GRAEMLIN_URL%%/smile.gif

CYCLE 1
03-21-2004, 06:18 PM
Not sure what series it is but is
the smaller one with a digital display.

On a personal note I generally only use my
tach to check gearing especially at TWS
I have so much seat time on a SV and the
limiter is so soft that I dont rely on it
much, and very seldom hit the limiter.
/ubbthreads/images/%%GRAEMLIN_URL%%/smile.gif

jroberts5407
03-21-2004, 07:50 PM
Yeah you hit on our problem. Two of the three team members (I'm one of them) are completely new to the SV and thus could use the tach feedback. I messed up several times I'm sure on the front straight either short shifting, or hitting the rev limiter, or trying to shift into seventh gear /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif . With my well-ventilated (noisy) helmet and ear plugs I could not hear the engine at all on the front straight, even in a full tuck. Plus even if I could hear it my 'ear-tach' is calibrated for an I-4. /ubbthreads/images/%%GRAEMLIN_URL%%/smile.gif

jroberts5407
03-21-2004, 07:50 PM
Yeah you hit on our problem. Two of the three team members (I'm one of them) are completely new to the SV and thus could use the tach feedback. I messed up several times I'm sure on the front straight either short shifting, or hitting the rev limiter, or trying to shift into seventh gear /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif . With my well-ventilated (noisy) helmet and ear plugs I could not hear the engine at all on the front straight, even in a full tuck. Plus even if I could hear it my 'ear-tach' is calibrated for an I-4. /ubbthreads/images/%%GRAEMLIN_URL%%/smile.gif

Rich Desmond
03-21-2004, 08:28 PM
John, Scott's got an older model My-Chron light that has tach and lap timer, nothing else. Unfortunately I think My-Chron has discontinued that model, the only ones I've seen lately that have both are the Mychron 3 models, for a lot more money. If you only need the tach there is the My-Chron MRT Lite, it also has a temp input. Here's one source for them:

http://www.clearlight.com/~laukrace/2000/gauges.htm

A google search would turn up more I'm sure.

Rich Desmond
03-21-2004, 08:28 PM
John, Scott's got an older model My-Chron light that has tach and lap timer, nothing else. Unfortunately I think My-Chron has discontinued that model, the only ones I've seen lately that have both are the Mychron 3 models, for a lot more money. If you only need the tach there is the My-Chron MRT Lite, it also has a temp input. Here's one source for them:

http://www.clearlight.com/~laukrace/2000/gauges.htm

A google search would turn up more I'm sure.

CYCLE 1
03-21-2004, 09:31 PM
Rich, that is not the only old model on my bike! /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif
Formula fifty is going to be great
of course you will be waiting for me. :p

CYCLE 1
03-21-2004, 09:31 PM
Rich, that is not the only old model on my bike! /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif
Formula fifty is going to be great
of course you will be waiting for me. :p

Rich Desmond
03-22-2004, 06:22 AM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Scott Levine:
Rich, that is not the only old model on my bike! /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif
Formula fifty is going to be great
of course you will be waiting for me. :p </div></div>Yeah, there's that one old, worn out loose nut on your bike. Dunno why Randy hasn't fixed that yet. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

Rich Desmond
03-22-2004, 06:22 AM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Scott Levine:
Rich, that is not the only old model on my bike! /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif
Formula fifty is going to be great
of course you will be waiting for me. :p </div></div>Yeah, there's that one old, worn out loose nut on your bike. Dunno why Randy hasn't fixed that yet. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

CYCLE 1
03-22-2004, 08:09 PM
Sentimental value! /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

CYCLE 1
03-22-2004, 08:09 PM
Sentimental value! /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

Ronnie Hay
03-23-2004, 03:36 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
The tachometer reads correctly at idle but when the engine is revved, especially at the upper RPM range, the needle is very erratic, and wavers widely up and down. For example at 9000 rpm the needle is waving back and forth from 4,000-14,000 RPM.
</div></div>Sounds like voltage spikes on the input signal. If I may, I suggest a capacitor wired inline with the input signal. It may fix the problem. It often worked in the old EE labs. If it doesn't, you've only spent a couple of bucks and some time.
--
Ronnie

Ronnie Hay
03-23-2004, 03:36 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
The tachometer reads correctly at idle but when the engine is revved, especially at the upper RPM range, the needle is very erratic, and wavers widely up and down. For example at 9000 rpm the needle is waving back and forth from 4,000-14,000 RPM.
</div></div>Sounds like voltage spikes on the input signal. If I may, I suggest a capacitor wired inline with the input signal. It may fix the problem. It often worked in the old EE labs. If it doesn't, you've only spent a couple of bucks and some time.
--
Ronnie

jroberts5407
03-23-2004, 04:58 PM
Hey Ronnie do I run it in-line or connect the input to ground through the capacitor (like a low-pass filter)? Guess I could just try both since I already have the capacitors.

jroberts5407
03-23-2004, 04:58 PM
Hey Ronnie do I run it in-line or connect the input to ground through the capacitor (like a low-pass filter)? Guess I could just try both since I already have the capacitors.

Jack Giesecke
04-13-2004, 08:02 AM
I bought an inductive tach, a Scitzu (sp?) shipped from England. Mine is a self contained unit, nicad battery that's rechargeable from a car battery. You just lay the pick up wire along side a spark plug wire and it induces the signal from the plug firing. It works VERY well and does not connect to any of the motorcycles electrics, so electronic noises in the ignition shouldn't be a factor. They make models for about any type bike, some that are driven off the bikes battery so you don't have to charge it. The nicad is supposed to last 8 hours, I know it lasts a 4 hour endurance just fine. I originally got it for the KX when we were tuning things. We needed to know what rpm we were working with to do the porting and such. Then, I stuck it on the XR when I built that bike because the XR fires a waste spark, so it worked fine on that bike. They have models for 4 stroke bikes that don't fire a waste spark, too, and models that go up to 16K rpm. I gave about $160 American for mine and have been very satisfied with it. I don't run it anymore on the bikes. I mean, on the little tracks I run these bikes on, if you look down at the tach, you'll be running past your braking point for the next corner. I just bought it for engine development on the KX and used it once on the XR. Turns out the XR runs out of juice at 12,500 and it should be good to 14,000, so it has sort of a built in rev limiter. It just won't pull above 12,500.

Jack Giesecke
04-13-2004, 08:02 AM
I bought an inductive tach, a Scitzu (sp?) shipped from England. Mine is a self contained unit, nicad battery that's rechargeable from a car battery. You just lay the pick up wire along side a spark plug wire and it induces the signal from the plug firing. It works VERY well and does not connect to any of the motorcycles electrics, so electronic noises in the ignition shouldn't be a factor. They make models for about any type bike, some that are driven off the bikes battery so you don't have to charge it. The nicad is supposed to last 8 hours, I know it lasts a 4 hour endurance just fine. I originally got it for the KX when we were tuning things. We needed to know what rpm we were working with to do the porting and such. Then, I stuck it on the XR when I built that bike because the XR fires a waste spark, so it worked fine on that bike. They have models for 4 stroke bikes that don't fire a waste spark, too, and models that go up to 16K rpm. I gave about $160 American for mine and have been very satisfied with it. I don't run it anymore on the bikes. I mean, on the little tracks I run these bikes on, if you look down at the tach, you'll be running past your braking point for the next corner. I just bought it for engine development on the KX and used it once on the XR. Turns out the XR runs out of juice at 12,500 and it should be good to 14,000, so it has sort of a built in rev limiter. It just won't pull above 12,500.