Erratic tachometer
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Joined: Jan 2009
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Erratic tachometer
I was wondering if I was reading my service manual correctly;
Is the tach readout coming from the ignition coil and if so, if my coil was going bad would that explain the needle jumping all over the place?
Thanks-TB
Is the tach readout coming from the ignition coil and if so, if my coil was going bad would that explain the needle jumping all over the place?
Thanks-TB
Road Master
Joined: Jun 2009
Posts: 1,062
Likes: 20
From: Batavia, NY
well i was gonna just post a new thread, but ill dig this one up instead :-) tack, im having a similar problem on my 90 sporty 1200. its an aftermarket tach, one of the mini ones, and it just doesnt move smoothly. sometimes when i rev it up, the needle will dip, then go up to whatever rpms i rev it to. sometimes, it just fluctuates by almost 1000 rpm when the bike is held at a constant engine speed. i was just wondering if its just a crappy aftermarket tach, or if theres really something wrong with my bike. im completely new to harleys, ive only had this one for a week. anyone got any ideas?
Road Master
Joined: Mar 2009
Posts: 990
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From: Redondo Beach, California
I am just starting on my third tachometer now on the same 1999 XL883 with 48,000 miles on it. On the first one, the needle started jumping / bouncing around after it had been working perfectly for years and years. The second one started the same needle jumping around a little after I bought it from the dealer and when I went back they said that the warranty was only good for about six months because the vibration from the motor kills the tachometer and I had brought it back in to them a little after the warranty was over. (Oh, yea, of course I did!) I lived with the bouncing needle on the second tachometer up until just this week as the glass was broken out of it by hail while I was at Sturgis, SD this year. (I was lucky, the damage to some of my friends bikes and to other bikes and cars and trailers was very extensive!) This third new tachometer is working just fine at the moment, but I have the dated receipt and the hope that the third time is the charm. All I have had to do is just fit the new tachometer into the mount and then plug the original wire into the back of the replacement tachometer and put the backing plate back on and I am good to go. No problem so far. I cant answer your question about the feed coming from the coil, but if your motor is running normally and the needle on your tachometer is bouncing, I would feel that it is in the tachometer and not the coil. You should be able to remove the tachometer and have it tested to be sure. On the after market tachometer, I do not have enough information to be able to offer any solid, helpful hints for your situation. Good luck with your Sportsters and ride safe! 
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kewlthing
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Feb 23, 2013 06:19 AM
