Hello everyone, i've been lurking around the polaris forum for awhile now and have a question about swapping an air box on my 500.

I have a 96 model that has been sitting for about 4 years and i am trying to get it back going. I have a 2000 model with no engine that i would like to use the air box from since mine has broken studs and a nice hole that a mouse chewed in it.

I swapped em out and everything went smooth until i rode it and found that it wouldnt run right with the 2000 model box. It lost power and bogged down pretty bad and i couldnt figure out why.

The 2000 box is a somewhat different design but i didnt think it would effect the way it ran so drastically. I did some checking and found that the jets were different between the two years. 96 has a 140 main and a 42.5 pilot, 00 model has 155 main and 40 pilot. The air jets are both 160.

If i buy some new 2000 model jets for my 96 carb would the air box work correctly or am i missing something?

Also would a loose air box lid cause the classic bad cam symptoms of backfiring through exhaust and bogging down in the midrange? I replaced the cam several years ago due to the usual missing exhaust lobe. Yesterday i took it for a spin and it started backfiring when on the throttle so i pulled the cam and checked it with a caliper. Checked perfect.

I was standing there scratching my head and i noticed that the box lid only had one screw in it and it was loose. I am really hoping that was the issue but i havent had time to put the cam back in and seal the box up to try it.

 

Air inlet tube on the 96 air box was smaller than the 2000 air box which made sense on using the smaller 140 main jet.Air boxes have to be sealed to run right.If air boxes are sealed,no leaks in the intake boots,etc, shouldn't make that much difference between using the 96 and the better 2000 air box. Jets are fairly cheap. I'd get the 152.5 and a 155 and go from there. Not enough of a change to mess with the pilot jet.Also make sure the air box intake tube isn't touching the back of the tank when you sit on the seat as it could be blocking off air flow and cause problems. Older boxes did have a habit of breaking posts causing them to run lean and bog,but wasn't the cause of cam failure.That was caused by faulty heat treatment on the first cams.Not a bad idea to pull the black wire from the reverse limiter as they all fail eventually and they can cause limiting in forward range also. Item#31.

 

Thank you for the reply. I just got it put back together after checking the cam. I sealed up the holes in the old air box, checked the valve clearance and pulled the black wire and now it runs better than it has since i started this process of bringing it out of hibernation.

I believe the air box was the main culprit as the mouse hole was larger than i thought. That hole got sealed up with clear silicone caulk. I am gonna order the jets you recommended and see if i can get the newer box to work.

I have found more differences between these two year models than i had anticipated when i started. Thanks again for the help.

 

Yes quite a few changes from 96-2000 models.96 air box was faulty design,plus who wants to remove 6 wing nuts to remove an air box lid when spring clamps work so much easier.You're lucky that the mice confined themselves to the air box.If they really got hungry the wiring harness would have been next.

 

I agree that the old air box was a bad design. Not only did you have to deal with 6 wingnuts, the plastic would also crack and the studs/bolts could pull out if you tightened the nuts too much. The new design is so much faster and easier to take the lid off and put it back on. I've been lucky that the only mouse damage I've had so far was they chewed a hole in my pre-filter last year. I don't think the filter itself had a hole in it but can't remember for sure. Not bad for 20 years of outdoor storage.

 

The 96 seat wont clear the air box inlet on the 2000 box either, i guess im stuck with the old box for now.

I am gonna try to convert the 2000 rear brake setup over to the 96 tomorrow. The floating rotor design on the old bike has never been right. I bought an upgrade kit for it years ago from polaris that was supposed to fix the chatter but it didnt help much.

The kit changed the rotor from riding on the shaft to riding on six or so pins spread around the circumference of the rotor. Now it chatters on those pins instead of chattering on the tranny output shaft.

i hope the 2000 rotor and caliper will swap out without too much problem. Im not concerned with the foot brake working so it shouldnt be all that difficult. I will find out tomorrow i guess. thanks

 

Bummer on the seat hitting the intake. Can't think of a mod that would help. If you removed it,could cause more problems. I also hated the the first generation rotor as they would over heat and also the floating disc as you couldn't get this set up right and it always chattered.Never tried to swapped a 2000 rotor on the 96. Curious as to whether it works or not.Keep us updated.

 

The rotor was an easy swap but the caliper wouldnt fit. I was kinda surprised since the shaft on the 00 model was threaded on the end and the rotor was held in place with nut.

The 96 doesnt have the threaded shaft,just splined all the way out. The caliper wouldnt bolt up which is fine because i couldnt have used the foot brake with it anyway, 96 has a manual and the 00 has a hydraulic.

Stupid thing still chatters but not near as bad as it did with the setup i had. It had a fixed hub that attached to the output shaft with a compression clamp kinda deal. The rotor floated on bolts that screwed into this hub. I bought this "improved" rotor from a local polaris dealer when the splined center on my original rotor wore down and caused it to bind and chatter.

I havent seen one like it on any other quads. I guess they didnt sell many of these kits.

 

I fought with the old design along with the updated floating hub that came as kit and standard on the 97 Sportsman. Yes I forgot the later models splines were threaded on the end.Transmission brake worked great on the old Husky 406,but Polaris couldn't get it right.They finally solved the problem when they moved the brake off the transmission and moved it to the rear drive shafts.

 

i didn't realize it came stock on the 97 models, thanks for the info. Is there any way to minimize the brake noise on the 96's ? I plan on selling mine when i get everything sorted and i'm afraid the noise might spook a potential buyer.

It's a scary sound and kinda hard to believe it's coming from the brakes unless you're as accustomed to it as i have become over the years.