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Sputtering Suzuki 500cc motor

  #1  
Old 11-14-2018, 06:31 PM
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Default Sputtering Suzuki 500cc motor

I recently inherited a 2000 arctic cat 500 automatic atv and am trying to get it ready for the upcoming ice fishing season. I thought everything was fine on it since my grandpa took good care of his stuff. It starts and runs fun until you get much above 15 mph then it spits and sputters like itís choked for fuel. I have the carburetor off now and am going to attempt to rebuild it with a rebuild kit. While I was looking it over this evening I noticed that a couple of the wires going to the the rectifier were cut (a blue and a black. They were then connected to each other on the harness going to the rectifier via a butt connector. It was by no means a recent thing either. Could this have been done to act like a governor? I am by no means a mechanic but would like to fix this myself so that I donít have to pay a shop $100/hr to do it. I have picture attached (I think) please help!!!!

thanks in advance
 
  #2  
Old 11-15-2018, 01:01 AM
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Your regulator has 2 connectors, correct? My Suzuki 500 is like that. In the 4-pin connector, the power and ground are spliced so each goes to 2 of the 4 pins. My reg is bad and I have just ordered a new aftermarket one. It was charging at over 16V.

As for pix, I have had no luck using the "go advanced" button, but the image icon works.
 
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Old 11-15-2018, 07:10 AM
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Last edited by scootergptx; 11-15-2018 at 07:32 AM.
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Old 11-15-2018, 07:33 AM
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Tried to edit the link, but it says the page can't be found. Are you trying to post a picture or a link to a page?
 
  #5  
Old 11-19-2018, 01:24 PM
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I just replaced the regulator/rectifier with a new aftermarket unit, and it works properly, charging at 14V.

You can run your quad completely without the reg/rect and you will probably have the same sputtering symptom. Note that the CDI
on your AC or my Suzuki LT-A500F contain signal processing ICs and are quite complicated. My similar problem persists.
 
  #6  
Old 12-19-2018, 11:29 AM
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This is what I just found out about my 99' arctic cat atv problem... I'm changing mine out today....

Mine just started it's problem the other day and it wouldn't throttle up after idle. Just spit, spat and sputtered while tyrying to rev it up.... I'd turn the headlights on and it would rev a little, and then squeeze the brake on the handlebar and it would also rev up.... I just knew it had to be an electrical problem rather than a carb issue....btw- The carb was just rebuilt a few weeks ago and system thoroughly cleaned out and replaced hoses as well...
 
  #7  
Old 12-19-2018, 12:11 PM
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I have eliminated all the CDI kill signals potentially causing my problem: temp switch, gear position input, etc. Gonna try a new coil next.
Spec for HV coil + cap is about 20K Ohms.

I have an engine oscilloscope hooked up, and I do not seem to lose the spark, but the problem does still seem to be
electrical. My carb is brand new Mikuni, and the CV piston/diaphragm move smoothly. Fuel flows freely into the float bowl. A
fuel starvation problem does not manifest with exhaust system backfires in my experience (100s of engines). That cause is also easily
eliminated by squirting fuel into the intake when the sputtering starts.

If just changing your CDI, pls report if that works.
 
  #8  
Old 12-20-2018, 03:03 AM
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The first thing to do with a suspected regulator problem is check what voltage it is putting into the battery. Over 15v and you may well get ignition problems, not sure why as, in theory, the ignition is from an entirely separate coil. Another possibility is the loose magnet syndrome. I thought this impossible too, for a long while, because the only one I had destroyed the stator, as the loose magnet jammed between the others and stator. However, I had an Eiger last year with the unfathomable spluttering, removed the alternator case and found loose magnets on the flywheel.
 
  #9  
Old 12-20-2018, 11:14 AM
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That is interesting, MM. I have yet to run into the detached magnets as you have. Seems later engines hold theirs in with more
than just glue. In your case above, it seems you would be getting erratic spark and charging at all RPMs.

The extra-high voltage from a failed reg probably damages the electronics in the CDI. Those regulator diodes get really hot, then the
potting cracks and water gets in. Super-easy to check, and regs are cheap.
 
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