Hey guys. This weekend I bought a Polaris Xpress 300 2wd from a guy local. I paid $400 for the machine running and driving. Didn't seem like too bad of a deal since it actually looks ok, and is pretty tight as far as bushings and bearings, but it needs slightly more mechanical work that I was thinking it might. Ill try to run through what it needs. Ive rebuilt several ATV's, but this 2 stroke is a new venture for me as far as ATV's go so im trying to learn it as I go. The machine needs an air filter and brakes which Ive already ordered. Its leaking oil somewhere around the middle of the machine, so ill need to find and fix that. The battery is bad, and the lights don't work with the machine running. Im doubting the starter works either which seems to be common on these since its under the engine.


Now for the items I need some help with.


1 - The engine starts on the first pull warm or hot. I haven't checked compression but it seems to run well with no spitting or sputtering, but it smokes like crazy. Much more than what would be normal. I took the air filter out and rode it for a quick check and it smoked just as bad. The tank looks like it has premix in it. Which means if the oiler is working that it is getting double the oil it needs. So, I may pull the tank and clean it because its dirty in there anyway. Then I can add regular gas and go from there. But before I do that, is there any way to make sure the oiler is working correctly? The throttle cable moved the metering arm just like it should, and I have heard OPT say the injection system is pretty reliable. It looks to inject right into the carburetor.


2 - It seems to have pretty good power, but it just keeps revving and never seems to really speed up like it should. You have to push it hard to get to what feels like 25-30mph and the engine is really screaming. So, my guess is the clutch needs a little work of some kind. Any ideas on where to start there? It seems to grab ok off idle, but it just never seems to change up into the high ratio. Im assuming this thing would surely run 40mph and get there reasonably fast when everything is right? What are the symptoms of a worn belt on one of these?


Those are my two biggest concerns at the moment. The clutch cover is also messed up and im not sure what the issue is there. It is all on the machine, but it has gaps in it and doesn't seem to mate up well. I need to pull that off and see what the deal is. My plan for this machine is to fix it up best I can for cheap and sell it to a good friend that has been looking for an ATV. Also, anything else I should know about these 2 strokes is welcome. Im pretty good with 4 strokes, but still learning these. Thanks for any help, and sorry for the long post!

 

Before you do anything do a compression check to see where you stand on the top end.Oil build up over the years in the exhaust pipe and muffler along with possibly too much gas from the carb(float level off) can make one smoke like a chimney.You can have a pipe/muffler vatted or just plug up the muffler and soak it in kerosene for a few days. This will help a little. Plus it's gonna smoke one way or the other because it's a 2 stroke. To check if the oil pump is working,have the machine at an idle,raise the pump arm all the way up,pull the injector line from the carb,should be a small dribble of oil. If the machine rpms rise ,but power is low,I'd check into the clutches and belt. Guide button wear on the front clutch,but the main culprit is usually the rear ramp buttons worn down along with a worn out belt.Place a straight edge over top of the clutches and pull down on the belt. If you have over 1 1/2" slack from the top of the belt to the straight edge,belt is worn down. Belts wear down on the width along with stretching. Older model clutch covers could warp and hit the drive clutch. They were formed too close to the shape of the clutches,didn't have enough room for air to circulate. Just get a 2000 or later clutch cover from ebay,etc and should solve the problem. You may have to improvise on the air exhaust duct or get one that goes with the later model cover as the exhaust tube is larger. Plus get a cheap manual,can help you on a lot of things to check/repair. Don't know what year model you have,but there are plenty like this.DOWNLOAD 1996-1998 Polaris ATV Repair Manual ALL MODELS - Download ...

 

Thanks for the quick reply OPT.


Ill do a compression check pretty soon and see what comes of it. Also, what are symptoms of bad crank seals? I know on smaller 2 strokes they will lean out and wont idle. The starter is pretty oily, so its either dripping off of the oil pump/hoses or a crank seal im assuming. I don't mind putting in crank seals if I have to, but Im hoping the rest of the engine is solid. How reliable were these engines if they were treated decent?


Im thinking my game plan right now is to pull the front plastic and check out everything. The tank needs cleaned anyway, so It will give me good access to everything. Thanks for the advice on the clutches. I will look at the belt and clutches. Im going to guess it hasn't had any clutch maintenance for a long time. Im pretty sure that is the only real performance issue I have, but the engine smokes a LOT. Ive seen video's of these and one that is right doesn't smoke near as much as mine does. Mine smokes heavy even right after startup when nothing has built up much heat, so im thinking Its not from buildup in the pipe. Im really thinking the gas in the tank looks premixed, so if the oiler is working, that may be my issue since it could very well be getting double the oil it should be.


Thanks for the help. I like a good project, and this is something new for me. The simplicity of this little machine is pretty neat to me. Once you get one in good shape, it would seem to me that it would be easy to maintain.

 

If it cranks up ok,idles good,throttles up ok(except for the clutches) then crank seals sound like they're ok. Normal signs of leaking seals are hard staring,erratic idle or wont start at all. Another thing other than possibly having it double dosed(premix and oil pump together) is if the carb needle and seat are worn,too much gas getting into the cylinder can cause excess smoking also. Just dump the tank of old fuel and see if that's the problem,plus make sure you check the pump operation also. Plus get a good filter and air box as 2 strokes especially don't like dirt..Oily starters means some fuel has leaked past the seal behind the stator,but I've found a lot like this that sat up a while still ran ok. Overall good engines,a bit more engine noise than the 250,but we sold a bunch of them over the years.

 

By that description, id say the crank seals are probably ok. The airbox is still in good shape, it just needs a good cleaning. The air filter was FILTHY. Ive got a new one ordered. That makes me feel a little better about the starter being oily. Might be something I don't need to worry about at the moment.


I did get the machine pretty far apart tonight. I pulled the front rack/plastic, the gas tank, the left hand floorboard and the clutch cover. Gave me good access to check everything. Ill try to make this somewhat composed without just rambling.


- The Oiler works fine. I got a dribble at idle with the oiler arm in the wide open position so I don't think I have any issues there, aside from all the hoses look like they need replacing.


- The compression is right about 120psi. OPT, do you know what healthy compression is right off? Im thinking 120psi should still be good for a while?


- The crankshaft seems to have no movement that I could tell so im thinking crank bearings are good.


- The backing plate for the clutch cover was broken in half and the clutch cover has a big hole in the bottom of it. I found out the reason pretty quickly though. The engine moves a LOT. Im not sure if it has a broken mount or rubber bushings that are totally deteriorated, but either way, im sure that's what broke the backing plate. Once I get the engine mounts sorted, I think I can fix the clutch cover and be good to go. I also think that's part of the reason for the loose belt, which has 1 3/4" + of slack on a straight edge. I think the mounts will fix some of that. I was ready to come to the house so I didn't look at the mounts yet. Hopefully its just something simple.


- What clutch covers and backing plates will fit this model? Im not sure what year it is. I need to get the vin off the frame and figure that out.


- On the picture of the clutch, you can tell the belt has not been to the top of the primary in a while. I took my fingernail and scratched a shiny place in it so its pretty easy to tell it isn't upshifting as it should. The engine mounts should tighten the belt and fix part of it, but I may still have some clutch issues.


Regardless, I know a lot more about it now than I did before, so hopefully I can just start fixing things now. Its a little more of a project than I first thought, but Im happy to know the engine seems solid.

Eric

 

120 is ok,but kinda getting down there. Main thing is that it's a running atv. Yes motor mounts can affect the clutches also. Get that sorted out,plus the manual I referenced shows about the ramp buttons in the rear clutch,guide buttons in the front that you can check out if need be,plus has good pics on repair/reassembling the rear clutch. Look on the right side of the machine at the front frame down tube. Should have a "W"96,97,98,etc. This will be the year model. Also if the engine number is still on the recoil housing,the first two digits are the year model also. Depending on year model,several different backing plates will work. Older model clutch covers had problem on warping and melting hitting the drive clutch at an idle. Later model (98 and up) larger covers can be substituted if needed. One of the cheapest places for oem parts is here.
http://www.cyclepartswarehouse.com/f...Vs&mfg=Polaris Plus always check ebay for used parts.

 

What would be considered a very healthy engine as far as compression? I had a hard time finding much on google that seemed accurate. Ill have to check out the manual you posted. Ive been working late for a while now and haven't had much time lately. Im hoping that's about to change though.


I looked a little tonight and it looks to me like the motor mount bolts are just really really loose. Looks like maybe it has two rear mounts and one front one? The front one seems ok, but the rear ones look really loose. I didn't crawl underneath it because I didn't really have time, I was just trying to shine a light down through between the engine and transmission. I think the mounts look like an easy fix though.


I forgot to look at the frame while I was down there, but I will check and see what year it is, that will help me out some. I think I can find a clutch cover on ebay probably. Ill figure out what year it is and maybe you can tell me which clutch covers/backing plates would work for me.


On the carb, when I pulled on the oil line to pull it off to see if the oiler was pumping, It pulled out a little brass nipple piece with the oil line. Im assuming this needs to stay in the carb. Would some fuel resistant epoxy work, or what is the best way to go about keeping it in there?


Thanks!

Eric

 

On new top ends I usually had around 130-135 psi. 120 isn't too bad.May last a while longer before you need to freshen up the top end. Yes you can epoxy the injector nozzle in the carb,as I've done the same thing..

 

The top end seems pretty cheap to do anyways. Im hoping it will go a while without it though. Sounds good on the injector nozzle. It fits snug, but it will pull out if you tug on it, so I think ill epoxy it in.


I did find on the frame rail above the battery is a sticker that starts with W97. So im assuming the machine is a 97 model. However, the engine sticker starts with 94. So, im not sure if someone swapped engines at some point or what? It doesn't really matter, as im sure it would be the same. Can you tell me based on this information what clutch covers I could be looking to buy? What models and years would fit this machine?


I noticed all the light bulbs are blown too. Im assuming that would be from running with a dead battery? Ive noticed though that the neutral and reverse lights work if I hook up jumper cables, but with the machine running and no jumper cables, those lights don't come on. Does that indicate an issue with the charging system?


I took a little video. I know its not much, but I brought it up to pressure wash it and get it halfway clean to work on so I took a short video afterwards.


Thanks!

 

This is the updated clutch cover.Used on a lot of different machines.

Usage : 5433542

Year Product Model Assembly
2000 ATV TRAIL BOSS CLUTCH COVER - A00AA32AA (4949914991C002)
2000 ATV TRAIL BOSS CLUTCH COVER - A00AA32AA (4949914991C002)
2000 ATV TRAIL BLAZER CLUTCH COVER - A00BA25CA (4954825482C004)
1999 ATV TRAIL BOSS CLUTCH COVER - A99AA25CA (4949594959b010)
1999 ATV TRAIL BLAZER 250 CLUTCH COVER - A99BA25CA (4949574957c003)
1999 ATV SPORT 400 CLUTCH COVER - A99BA38CA (4949534953c004)
1999 ATV SCRAMBLER 400 CLUTCH COVER - A99BG38CA (4949664966c006)
1999 ATV SCRAMBLER 400 CLUTCH COVER - A99BG38CB (4952505250c006)
1999 ATV XPRESS 300 CLUTCH COVER - A99CA28CA (4949444944b014)
1999 ATV XPLORER 300 CLUTCH COVER - A99CC28CA (4949484948c005)
1999 ATV XPLORER 400 CLUTCH COVER - A99CG38CA (4949634963C008)
1999 ATV SPORTSMAN 500 RSE CLUTCH COVER - A99CH50AC (4952455245c006)
1998 ATV SWEDISH SPORTSMAN 500 CLUTCH COVER - S98CH50E(B) (4950135013c006)
1998 ATV SWEDISH SPORTSMAN 500 CLUTCH COVER - S98CH50E(B) (4950135013c006)
1998 ATV SPORTSMAN 500 CLUTCH COVER - S98CH50E(B) (4950135013c006)
1998 ATV SPORTSMAN 500 CLUTCH COVER - S98CH50E(B) (4950135013c006)
1998 ATV SPORTSMAN 500 CLUTCH COVER - S98CH50E(B) (4950135013c006)
1998 ATV SPORTSMAN 500 CLUTCH COVER - S98CH50E(B) (4950135013c006)
1998 ATV TRAIL BOSS CLUTCH COVER - W98AA25C (4945314531B010)
1998 ATV NORWEGIAN MAGNUM 4X4 CLUTCH COVER - W98AC42A (4945214521C002)
1998 ATV SWEDISH MAGNUM 4X4 CLUTCH COVER - W98AC42A (4945214521C002)
1998 ATV MAGNUM 4X4 CLUTCH COVER - W98AC42A (4945214521C002)
1998 ATV SPORTSMAN 500 CLUTCH COVER - W98CH50A (4945714571c006)
1998 ATV SPORTSMAN 500 CLUTCH COVER - W98CH50A (4945714571c006)
1998 ATV MAGNUM 2X4 CLUTCH COVER Magnum 2X4 W98AA42A (4945524552B013)
1998 ATV SCRAMBLER 400 CLUTCH COVER Scrambler 400 W98BC38C (4947254725C006)
1998 ATV SPORT 400L CLUTCH COVER Sport 400L W98BA38C (4947234723C003)
1998 ATV TRAIL BLAZER CLUTCH COVER Trail Blazer W98BA25C (4945464546C002)
1998 ATV XPLORER 300 CLUTCH COVER XPLORER 300 W98CC28C (4945264526C005)
1998 ATV XPLORER 400L CLUTCH COVER XPLORER 400L W98CC38C (4945414541C004)
1998 ATV XPRESS 300 CLUTCH COVER XPRESS 300 W98CA28C (4945364536C001)
1997 ATV SWEDISH MAGNUM 6X6 CLUTCH COVER Magnum 6X6 W97AE42A and Swedish Magnum 6X6 S97AE42E (4940754075C012)
1997 ATV MAGNUM 6X6 CLUTCH COVER Magnum 6X6 W97AE42A and Swedish Magnum 6X6 S97AE42E (4940754075C012)
1997 ATV SCRAMBLER 500 CLUTCH COVER Scrambler 500 W97BC50A (4943074307C007)
1997 ATV XPLORER 500 CLUTCH COVER XPLORER 500 W97CD50A (4941354135C009)
1997 ATV XPRESS 300 CLUTCH COVER (300) XPRESS 300 W97CA28C (4939603960C007)
1997 ATV XPRESS 400 CLUTCH COVER (300) XPRESS 300 W97CA28C (4939603960C007)
1997 ATV XPRESS 300 CLUTCH COVER (400L) XPRESS 400L W97CA38C (4939603960C008)
1997 ATV XPRESS 400 CLUTCH COVER (400L) XPRESS 400L W97CA38C (4939603960C008)
1997 ATV TRAIL BLAZER CLUTCH COVER (SPORT) Sport 400L W97BA38C (4940124012C005)
1997 ATV SPORT 400L CLUTCH COVER (SPORT) Sport 400L W97BA38C (4940124012C005)
1997 ATV TRAIL BLAZER CLUTCH COVER (TRAIL BLAZER) Trail Blazer W97BA25C (4940124012C006)
1997 ATV SPORT 400L CLUTCH COVER (TRAIL BLAZER) Trail Blazer W97BA25C (4940124012C006)
1997 ATV Swedish Sportsman 50 CLUTCH COVER - W97CH50A (4939993999C010)
1997 ATV SPORTSMAN 500 CLUTCH COVER - W97CH50A (4939993999C010)
1997 ATV Big Boss 6x6 400L CLUTCH COVER BIG BOSS 6X6 400L W97AE38A (4940814081C007)
1997 ATV BIG BOSS 6X6 400L CLUTCH COVER BIG BOSS 6X6 400L W97AE38A (4940814081C007)
1997 ATV MAGNUM 2X4 CLUTCH COVER Magnum 2X4 W97AA42A (4940704070B013)
1997 ATV NORWEGIAN MAGNUM 4X4 CLUTCH COVER Magnum 4X4 W97AC42A, Swedish Magnum 4X4 S97AC42E and Norwegian (4940834083C001)
1997 ATV SWEDISH MAGNUM 4X4 CLUTCH COVER Magnum 4X4 W97AC42A, Swedish Magnum 4X4 S97AC42E and Norwegian (4940834083C001)


Plenty of good used ones on ebay,Cycle Parts Warehouse for a new one or you can even go to a bulbous type larger cover,but you'd have to have the larger exhaust air duct also. Blown out bulbs are common on machines run without batteries. Power from the regulator has to go somewhere and bulbs have the least resistance. Check that charging is ok with a good battery,a little above an idle should be at least 14 volts. Engine sounds noisy like a 300 should.. Does show a little exhaust leak up front. Could be at the head pipe gasket or the bell part of the pipe,common area for leaking as they wear. You can use some rtv to help seal this up.