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1987 Polaris Trail Boss 250 Air Box

  #1  
Old 01-05-2018, 11:45 AM
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Default 1987 Polaris Trail Boss 250 Air Box

My daughter has this ATV and the airbox is all broken up. I took it off once and discovered the reinstallation to be a real bear... So we bought her a new airbox and filter for Christmas. I wanted a couple of opinions before I try to install this one and break it too.


It seems like the carburetor boot needs about an inch or so of clearance but when I set the airbox into its mounting location there is less than a quarter of an inch between the carb and the airbox. The airbox flange will only take so much pressure before it cracks.


Any ideas on this?


Thanks,
Kevin
 
  #2  
Old 01-05-2018, 05:00 PM
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I know exactly what you're talking about as I used to fight these old air boxes also. Found a better way to do it. Install the boot and clamp at the carb first,slide the air box clamp up on the rear of the boot.Run a little oil around the inner part of the boot and work the boot on the air box neck.Slide the clamp down and tighten it around the box neck.Then you can pull the box back far enough to mount the two box screws to the frame.The boot will stretch a little but the clamps are tight.Forgot to mention that it may be easier to stick your finger inside the box and push down on the boot and work it around to get it to slip over the neck.
 
Attached Thumbnails 1987 Polaris Trail Boss 250 Air Box-c0b21c6b99d42aa1bc7e162d2ab6b162d8e6e3e6.png  

Last edited by old polaris tech; 01-05-2018 at 06:39 PM. Reason: working inside the box..
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Old 01-09-2018, 03:24 PM
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That was awesome OPT! I did as you suggested and it slipped into the boot like an egg being sucked into a bottle.


I believe I have some additional adjustments to make. It runs fine as long as the air box is off and the air mixture screw is all the way in. Any air mixture screw adjustments make it sound like it is starved for fuel.


With air box and filter installed it bogs down after about 1/3rd throttle. Same results when adjusting the air mixture screw.


Battery has 13.06 volts.


As always, any assistance is much appreciated.


Thanks,
Kevin
 
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Old 01-09-2018, 04:24 PM
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Running too rich if you have to have the air box off. Before you go too far do a compression test. If less than 100 psi that can be a problem no matter what you try to do to the carb. Eliminate that area first. If compression is beyond 100 psi a simple carb kit may solve the problem.https://www.ebay.com/itm/Shindy-Carb...JYLkGx&vxp=mtr The air screw should be between 1.5 - 2 turns out in most cases.Leaking crank seals can be another problem,but check out the other things first.
 
Attached Thumbnails 1987 Polaris Trail Boss 250 Air Box-s-l500.jpg  
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Old 01-09-2018, 05:27 PM
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Default 1987 Polaris Trail Boss 250 Air Box

Well I got to say that I have been proven wrong again. I remembered before I put the battery in, that it was spitting and sputtering on the high end.

I have put a new battery in but it apparently is not charging and even though the battery has 13 volts, I decided to disconnect the battery and test ride. It flies like a bat out of Hades. Something in the charging system is causing the ATV to bog down. The starter works when the battery is connected it just will not run at high end.

I think I'm going to install a disconnect switch on the ATV for my daughter to use when starting the unit and then when riding she can use the disconnect switch to disable the battery connection.

If I decide to work on it anymore I'll definitely check the compression.

OPT, you have been a world of help to me and I really do appreciate it. This thing will be good for my daughter to ride on considering it's 31 years old now.

Thanks,
Kevin
 
  #6  
Old 01-09-2018, 05:42 PM
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Don't drive it without a battery! It can crank and run,but needs the voltage for the regulator,lights,electric starter,etc.Regulators were the most common thing to fault on charging. You can get these cheap on ebay or amazon. https://www.ebay.com/itm/Rectifier-R...1TeynR&vxp=mtr This and the reverse limiter module under the front panel may be part of the problem. Pull the black wire from it and if it's been limiting in forward range as many have done,this will bypass it. Plus you won't have to push the reverse over ride in to have full power in reverse. Item#33 in the parts break down.
 
Attached Thumbnails 1987 Polaris Trail Boss 250 Air Box-d3a67fe598b91b72cc394b863a17fc98d2fc632e.png   1987 Polaris Trail Boss 250 Air Box-s-l1600.jpg  
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Old 01-09-2018, 06:23 PM
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Yeah, you make a valid point but I'm dealing with a twenty-four-year-old who is married and on her own now. She purchased this ATV for $350 and doesn't want to put any more money in it.
My hands are kind of tied unless I pay for the repair parts myself and I really don't want to do that. LOL The lights haven't worked since she bought it so I figured there was some problem with the charging system and I'm no electrician so I haven't looked into that yet. I thought when she bought it the reverse override was working but it is not working now. I'll have to try to disconnect it per your instructions and reconnect the battery and see if that allows the unit to run on its high-end.

Thanks,
Kevin
 
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Old 01-23-2018, 06:59 PM
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Ok, so I purchased the Regulator from the link that you sent to me. The wire colors are different from what's on the ATV. One of the wires is separate from the other two as is the case on the new regulator as well. They also have different connectors than the OEM so I'll need to replace those.


Do the wires just connect in sequence?


Thanks,
Kevin
 
  #9  
Old 01-24-2018, 04:50 AM
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On some after market regulator colors may be different along with connectors. Some may have bullet connectors,some may have spade connectors.Just match up the solid colors first to eliminate them,then you can usually tell on the striped connectors which one goes where.
 
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