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Tach reading way too high...

Started by moelarrycurly, April 21, 2018, 09:10:25 PM

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moelarrycurly

April 21, 2018, 09:10:25 PM
Hi Guys!

   I've been working (slowly as the budget allows) on restoring/modding my 84 FJ1100. I replaced my ignition system (yes the whole thing) with a Dynatec Dyna 2000 kit. It has been fantastic. No worry cold starts-even at 20 degrees. really a huge improvement on reliability too... Only problem is my tach reads about double what it should. 2000 rpm at idle and 6500 rpm at 55 mph in 5th gear. Anyone know how you calibrate one of these stock units?

Thanks guys!

Jason

aviationfred

#1
April 22, 2018, 02:36:30 AM
Here are gearing charts for the FJ with lists of sprocket sizes and tire sizes. http://www.fjowners.com/index.php?topic=669.0

Having just completed the installation of a set of Speed Hut gauges. The GPS speedometer and stepper motor driven tachometer together read spot on when compared to the above mentioned charts.

I have no personal knowledge of the Dyna ignition system or how it is set up. I will mention that during the installation of the Speed Hut tachometer, there are directions that tells you how to set the tachometer to read the correct engine ignition pulses. The gauge is pre-set to indicate 4000 rpm in the pulse menu. For the tachometer to read the correct rpm's, the gauge needs to run through the pulse setting procedure and be set at 1000 rpm's.

I know this has nothing to do with your Dyna ignition, but I wanted to point out that the Dyna ignition is a universal item just like the Speed Hut tachometer. The FJ engine is a wasted spark engine. You may want to try setting the Dyna to read as if the engine is a 2 cylinder.


Fred
I'm not the fastest FJ rider, I am 'half-fast', the fastest slow guy....

Current
2008 VFR800 RC46 Vtec
1996 VFR750 RC36/2
1990 FJ1300 (1297cc) Casper
1990 VFR750 RC36/1 Minnie
1989 FJ1200 Lazarus, the Streetfighter Project
1985 VF500F RC31 Interceptor

Bones

#2
April 22, 2018, 04:01:39 PM
The tach has a trim pot that you can adjust for fine tuning, only trouble is gauges have to come apart to get to it, plus you need another tach of some sort hooked up to tune it to. I remember I think it was Skymasters who did a write up with pics about the subject.
93 fj1200
79 suzuki gt250x7


Too young to be old but old enough to know better.

Mike m

#3
April 22, 2018, 06:45:10 PM
That moment when you met the guy you passed on the freeway and he says I was just cruising.lmao

JMR

#4
April 23, 2018, 06:16:40 AM
  You have the 2/3 negative coil wire (Blue for the Dyna 2000) connected to the tach?
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