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2007 Kawasaki Bayou 250 I think. Electrical issue

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Hello everybody.  my name's love - from Bogota Colombia.


I have a Kawasaki Bayou 250 from 2007 that started acting weird.

What it does is that it starts up,  it idles fine.  Then when I accelerate it won't go past 4000-5000 rpms at all.  I used to be able to get up to 3-4th gear fairly quickly,  now it loses power and won't even kick into second.   It sputters horribly.


I figured it was a problem with the high RPM circuit in the carb.  took it out, cleaned it..... put it back in...started back up no prob - same thing - won't rev up.


Then I decided to do the battery test per the service manual I found online chapter 16-21 I believe.   It says that you connect the battery and test it as the atv is off- it should be slightly higher than 13v - checked out.  


it said to turn on the ATV and rev it up to 4000 RPMs.  the ATV sputters like crazy so this was extremely difficult but I got it - it said if the volts go way above 14v then the regulator is defetive and if it drops below then either the regulator or the alternator is defective.  


I tested out the alternator,  unplugged it (the one with the 3 yellow wires),  turned on the ATV and revved it up.  The manual said that it should go up to 38v at 4000rpms.  this did not go above 15....  so the manual says automatically the alternator has an issue.


I tested the resistance on the stator wires and it all checked out including testing out the grounds.... resistance showed zero so according to the manual the stator is good.


should be the magnetic rotor -  but I checked it with some bolts and they get stuck just as good as they did a while back - so it doesn't seem like the magnetism is lost on that part either....


put the whole thing back together and left it there with no idea where to turn...


has anybody had this happen?  Where you can turn on the ATV,  accelerate slightly -  but sputters at high end...


then the alternator seems to not be sending enough current to the regulator....  


what could it be?  Should I just buy another magnetic rotor and see how it goes? I'm stuck on this one.....






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When you checked  the voltage  at the battery, what readings did you get ? .. Engine off  battery  should read around 12.6 volts. . Engine running  revved up  a bit  voltage  should read  13.8 to  14 v.  If it  does ,  your  alternator  and regulator  are fine.  The  running symptoms you describe sound  more to  me to be fuel related.  If  you  are  getting any smoke  and carbon fouled spark plug it  is running   too  rich ,  and  if the plug is dry  and  very light  brown to  whitish  it  is  likely   too  lean. Check the  carb  again  for  holes in the diaphragm and plugged  jets . Check  also  for good fuel  flow to the  carb.  There  could be a restriction in the  line or in the  inlet  needle not allowing the  fuel bowl to stay  full under full throttle demand.

The   rotor will not be the problem. Magnets do  not  lose their  magnetism  and  unless the  very  unlikely  occurrence of  one coming loose there is really nothing else to  make it  fail electrically .

Most  often  when  there  has been a problem  with the  ignition  breaking  down  at  higher  revs,  it  has been   voltage regulator  problems others  have  found .   If running  voltage  remains around  13.4 to 14v at the  battery  the regulator should be  fine. There  is  an  inline  spark  checker  you  can  get to  see if the  spark  plug  is getting  spark  all  the time. If there  isn't   one available from  you  suppliers you  could  order one  online .  `There is the  possibility  of  the  CDI  box  or ignition  coil breaking  down    at higher  rpm,  but  I'd  thoroughly  check  out the  fuel  and  carb before  blaming other  components.

Something else to  consider,  some  quads  won't run  right  at  off idle speeds   if the  air cleaner box  is not  closed  and the filter  is  clean  and in place .

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I did this:

connect the multimeter on DC - to the battery terminals.

I revved the engine as high as she'd go,  the service manual said the battery it should stay at 14V - if it goes higher the regulator should be looked at.  if it is lower look at the alternator....

It stayed at 12.5-13 - and at higher revs seemed to drop to 9.....

So I checked the alternator by unplugging the 3 yellow wires.  checked the AC current out of those (alternator side)....  the manual said at 4000 RPMs it should increase to 38V.  but this didn't even go above 13-14.....

so I then figured it must be the alternator...


but do the symptoms match the problem?   high RPM losing power... sputtering.....  fuel smell  -  all the signs of running super rich,   I tried moving the mixture screw as far out as I could without it falling off and it still didn't fix the problem and after a certain point the mixture doesn't work at idle and it cuts out after after 1-2 seconds.....which to me seems like the carburation is OK... something else must be the issue.....

Should I change the spark plug?  I mean it's the cheaper option at the moment.. I changed out the fuse, cleaned out the terminals,  opened and cleaned every plug I could find....  this is a Kawasaki quad - let's be real these things are pretty solidly built...  every terminal was almost as if brand new and even the fuse I changed looked remarkably clean.....


also - FYI - I am in Bogota, we're at 8300 feet altitude and this thing operates at around 8500-9000 foot altitude.  things run rich here - it's just a fact of life....  I clean out the spark plug every once in a while - but I've had the quad for 2 years and it always ran fine  - 2 weeks ago it's showing these signs of trouble and I can't find a mechanic worth a penny in the town the machine is at.....  it starts, it idles... it just won't accelerate.....





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OK . It  won't be the rotor.  I'd suspect the voltage regulator, or  the stator  if you were getting bad readings from  it.  Can  you possibly  borrow another voltage regulator  to try ?   Voltage regulators  can fail  low  as well  as  high . It is a  little easier changing it than the  stator. I like to   try to  eliminate the easy before  going  for the  harder .  Is the ac voltage the  same across all  3  windings on the  stator? Are  you  using a  true RMS  reading  voltmeter or  one of the  cheapie  utility ones ? . The  cheaper ones usually read  low, and some can read  considerably  low especially  if the  ac  has a varying  wave form  or cycle rate.
Have  you  opened it up to get  a  Look at  it  and  the  pick up  coil for the  ignition.  I  don't  know  your  particular  machine model  but  at least on some machines  the pickup  coil for the ignition  could  come loose and the gap  could be  wrong ..  Gap between  it  and the rotor should be  about  .010"

Is the  clip  in the  top  notch on the  main   jet  needle.  If it isn't,  try that to  lean  it  out.    Otherwise  the  only way to  tune it for  your  altitude  would be to  rejet to  a size or  two  down.

Sorry   but beyond those suggestions I  can't be  of  more  help.


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