interesting problem and solution - Wrist Twisters
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post #1 of 9 Old 09-18-2008, 10:50 AM Thread Starter
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interesting problem and solution

The other day I made a trip to vist some friends, which was about 500km one way, when I got to my destination and shut the bike off the tach needle jumped up to about half way to redline. "Weird" I thought to myself but after sitting that long I was not about to worry about this little detail. However the next day when i fired up the bike the tach needle looped all the way around and came to rest on the point of the temp gauge needle. I reved the engine a couple times and all that happened was the tach needle pushed the temp gauge needle all the way up to hot. I shut the bike off and the needles both went back down to where they were before. I started the bike up again reved the engine the needles both went back up to hot on the temp gauge then with one more rev the tach needle snapped back around to where it belonged on the tachometer. It worked fine all the ride home.

Anyone else had this happen? Any idea of a cause?

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post #2 of 9 Old 09-18-2008, 12:19 PM
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Your bike is posessed. Sprinkle it with holy water.

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post #3 of 9 Old 09-18-2008, 12:26 PM
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Originally Posted by Sniper View Post
Your bike is posessed. Sprinkle it with holy water.
need a young priest and an old priest??

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post #4 of 9 Old 09-18-2008, 04:03 PM
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weird, probably the twilight zone, or possibly you entered into the 4th dimension parallel universe. whichever it was, don't do it again.

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post #5 of 9 Old 09-18-2008, 06:24 PM
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The '02 doesn't have the gauge needle sweep function like the later models, starting in '04 I think, which is intended to "pick up" the needle and return it to zero.
This will take some explaining.
In the good old days electric gauges were pertty conventional in that there was a light spring loading the needle toward zero with a coil of wire on the shaft that generated a magnetic field that countered the field of a permament magnet, moving the needle away from zero. The problem with this is changes in the coil, magnet, spring, or bearings would effect the accuracy of the gauge.
Current gauge movements operate a bit differently: the magnet is mounted on the shaft which is not spring loaded, and there is a small magnet and two stationary coils of wire wound 90 degrees from each other that generate magnetic fields proportional to sine and cosine voltage values of the angle the needle should point, generated by an integrated circuit. The PM is there to return the needle to zero, but only if it's less than halfway from its at rest position when the electronics are shut off. If the needle is past halfway it will go the wrong direction, coming to rest against the temp gauge needle. The only cure for this is to rev the motor past about 6,500 rpm, where the magnetic fields will pick up the needle and return it to its normal postion. This is the function of the key on sweep -- it makes sure the gauge is in the proper position.
I first noticed this when doing a plug chop -- the tach went the wrong way.
The only preventative measure is to make sure the engine is at idle when shutting down, or buy an '04 or later.


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On the other hand, if it has not been done never assume it is impossible to do it.
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post #6 of 9 Old 09-18-2008, 08:18 PM
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Originally Posted by barton664 View Post
need a young priest and an old priest??
Might want to throw in an alter boy just for good measure.

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post #7 of 9 Old 09-19-2008, 05:54 AM
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Concerning Robs definition and the magnets, I'm really afraid that you experienced a rare but not not too uncommon phenom where the hard seat of the 919 sent you into a temporary anal vortex. This can only happen when the barometric pressure is rising and at approximatley 30.666 milibars, at the same time the aligning of Jupiter, Mars and Uranus coupled with the reverse rotation of the Omega Delta Alpha Phatty Acid System giving off cosmic radiation bursts would have temporarilly bent the time space continuum. All of this occuring at the same time would have you metaphorically at the Latitude/Longitude : 32° 20'N, 64° 45'W of which everyone knows is the Bermuda triangle hence the reason for the gauge sweep.

I hope this helps.

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post #8 of 9 Old 09-19-2008, 06:58 AM
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Originally Posted by zookmor View Post
Might want to throw in an alter boy just for good measure.
oh snap now you guys are gonna have RC90 poking around "pun intended"

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post #9 of 9 Old 09-19-2008, 07:03 AM
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+1 Dadogs, LOL

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