I am going to look at a Polaris Xplorer 300 tomorrow with the hopes of bringing it home for my next project. I found this one that an old farmer bought to use around the farm but he never got to use it so it sat in his garage for some time till he decided to sell it. He bought it from the original owner who was an even older gentleman who used it around his house and plowed snow. The problem I have is, no one knows what year it is. How do I find the year from the numbers on the frame or the model number if I cant read what it printed on the front plastic cover? I know it is newer than a 96 or 97 because it has the black handle for the brake and the master cylinder tank is white. I am picking this up cheap enough that I could part it out and make money but it is in very good shape other than it just died and wont start. No cracks in the plastic, tears in the seat and the green is not faded a bit. It comes with a plow with a hand lift and has a winch also. The tires are about 75% and the electric start works. I guess this will give me something to tinker with during this cold wisconsin winter and I am sure I will have three daughters bugging me about getting it running as soon as spring gets here. How durable are these 300's? I know I dont have to deal with all the headaches of the 400 like the waterpump or the counterbalance, but is there anything I should look for as weak points on these motors? The machine itself looks very similar to my Xplorer 400 so that area will not be an issue, just the engine.

Thanks,
Mike

 

ATV Vin Number : Check and Decode Your VIN

 

Older models like the 96 or 97 had the model number and serial number on the right frame down tube by the gear shifter. Look for a "W96 or W97" on one side,the serial number on the other side.Sometimes the engine serial number is still visible and the first tr model also. What can go wrong other than the obvious is leaking crank seals for one thing on these old 300s. That I would expect if it's been sitting all these years with the fuel valve on like most are. Gas just floods the crank case and can destroy seals.I'd drain the 10mm crank case drain bolt at the bottom of the engine first to remove any trapped gas,then after the plug is back in do a compression check. May be a little low if the cylinder is dry. You can pour a couple teaspoons of oil in the cylinder and use the recoil several times then recheck compression. Needs to be at least a 100 psi for the top end. I'd still order seals if the compression and spark are ok.Polaris Xplorer 300 4x4 1996 1997 1998 1999 Engine Crank Seals | eBay The metal seal goes behind the stator,the rubber seal behind the drive clutch. Good machines,but noisy. We also sold a lot to farmers and ranchers and they were a good little work horse. Plus I'd premix the first tank of gas 50/1 along with the oil pump and take it easy for a little bit.

 

Thanks,

I kinda figured I would have to address the crank seals because it is an older machine, but I will do a compression test and probably pull the head to check the cylinder and piston for wear and replace it if it is wore. Did the 300's have issues with the piston skirts breaking like the 400's? If that is the case and it has an OEM piston still in it, I may just upgrade to a Wiseco to rule that impending problem.

Mike

 

If you plan on keeping it probably not a bad idea on going with a Wiseco along with new seals. They rattled,had more engine noise than the little 250,but we sold quite a few to farmers and ranchers that loved them. On early models Fugi went cheap with plastic oil pump drive gears,but after 96 went back to the metal drive. Oil pumps after that were bullet proof. ALOT easier to rebuild than the 400,but always check for any up and down play on the rod. If there is any have a new rod kit and bearings installed.

 

I bought the 300 today, got it for hardly nothing in my opinion. Took the winch and the plow off and already have that sold to cut my costs in half on the machine. I got it off the trailer and gave it a good bath to look it over. Everything is good and not much for wear. Chains are all tight and the gears look surprisingly like new. No play in the drivetrain or suspension so it appears to have low miles and an easy life. Checked the VIN and found out it's a 1999 model. I didnt bother with a compression check yet because, well, there isn't any, lol. I can pull the recoil and it pulls fairly easy, probably only about 30 pounds if that. There isnt any weird noises like scraping, banging or knocking when it turns over, just sounds like a normal motor, albeit turning over faster. I can hear air sucking and blowing when i pull the recoil, but dont know where it is going. I checked the block over real well and didnt see any cracks or holes so I'm ruling that out. Would crank seals being completely out cause low compression? I would think it would still have some compression if they were bad. I plan on picking up a complete gasket and seal set so they will be replaced anyways. The guy I got the machine from said his buddy works on atv's and said the 300's were known to break the bottom ring on the piston but this thing doesnt make any bad noises to point to that. Best case scenario I guess would be a blown head gasket and the worse case would be a hole in the piston. Either way, I guess I will pull the head and go from there. Another thing I want to be sure of is the temp sensor up by the head. How do I tell if its good and where do I get one if i is bad? I checked Partzilla and it said obsolete. The fan I can check with a jumper so I'm not worried about that.

Thanks for your help OPT. I guess after rebuilding my 400 last winter, I got the two stroke bug so I hope I can have good success with this project.

Mike

 

With a 2 stroke you need to have good top end compression and also bottom end compression. Even if the drive clutch side seal(most affected seal) was to pop out,wouldn't affect top end compression. Basically think of a two stroke as having two separate compression areas,top and bottom. Piston and rings if in good shape create a vacuum pulling in fuel/air/oil mixture.The bottom end compresses this mixture into a finer oily vapor that's shot up the transfer ports for further compression and ignition.If seals are bad,mixture can't compress and shoot up for ignition, if the piston and rings are bad,then can't create enough vacuum and compression to pull in fuel mixture and compress it for ignition. Top and bottom have to work together. ALL these old 300 fan sensors would either break from vibration or really never get hot enough to trigger the fan because they were located on the mounting bracket and not the engine. I'd just hook the two sensor wires to a toggle like a lot of people do and kick it on if driving slow or pulling loads at low speeds for extended periods.Most air cooled engines don't even have fans,but good to have if ever needed.

 

i took care of the whole not knowing for sure the temp...

 

This may be a dumb question, but where are the reeds on this 300? I looked the motor over and can't find a reed box. The carb boot is just that, a boot sealed with an o-ring. I looked online and boyeson makes a reed but it lists for a bunch of models but some people claim the 300's don't have reeds. I thought all 2 strokes had reeds. I ordered all new engine gaskets along with a carb kit to get me started so I can pull the head and cylinder off. Hope I don't find any surprises.

Thanks,
Mike

 

Nope,you can look all day and wont find reeds on the 300.. Simple little piston port engine that's just a straight shot from the carb into the cylinder. Told ya this was a lot easier than the 400.. BUT be sure to check for any up and down play on the rod after you remove the old piston or any bearing noise as you roll the crank around. I'd hate for a rod bearing to take out a brand new top end that you plan on installing.