Hello everyone, I'm new here and while I have been around ATV's for awhile, I'm fairly novice when it comes to two stroke motors.

Here is what I have. I have always had four stroke ATV's, my last was a Honda Rancher. Unfortunately, the dealer that I bought this ATV from used neglected to tell me that the bike was swamped at one time and I had nothing but problems with it. I took the dealer to court and got my money back plus additional money for the headache I had to deal with by running the bike back and forth to the dealer to get things fixed. After I got my money, I found out that a relative of mine had a Polaris Xplorer 400 for sale. The price was right and the machine was very clean. It came with a Polaris windshield and plow with a hand lift. He bought it from the original elderly owner said the plow was only used a couple of times. He trail road it and when he bought a newer bike, he passed it down to his son. He had the engine rebuilt at a little over 4000 miles and once he bought a new side by side, he gave his kid his other ATV and sold me this one last fall. It now has 4900 miles on it and I have not had any problems with it. I replaced the belt right after I bought it because I wanted to plow with it. I also replaced the battery when I installed a winch on it. Everything works on this machine. All the lights, the speedo, the fourwheel drive, everything...I run the Polaris VES synthetic oil in it for the two stroke oil. I always heard about the counter-balance oil being a problem and when I checked this one, it was a little dirty, but not milky. I have since changed it and check it every so often. The transmission oil is clean and I have changed that too. I grease this thing all the time, lube the chain and wash it after every trip out. I love this machine.

Now, you would think that with all this, I should have a great machine? Maybe I'm just paranoid but I seem to think that this ATV has something wrong with it. I noticed the other day when checking the coolant, that there is a sensor on top of the radiator that is not hooked up. I looked at the wiring diagram in the service manual and it is the fan switch. The wires that go to it are connected by a jumper wire so the fan stays on all the time. Is this ok to do? Or should I hook it back up and run the fan as it was intended. Another thing that bothers me is this thing is a gas hog. I mean a GAS HOG....not like my Rancher or the Yamaha Breeze we bought for the kids. I'm new to the two stroke bikes so when I drive this around, it has a smooth idle(not super smooth like a four stroke) but seems kinda choppy from off idle to about quarter throttle. It has great power when you open it up and even though I have only had it up to about 50 mph, it pulls hard and wants to keep going so I let off. I have heard other two strokes riding around our campground and they all sound kinda choppy at low speeds but I cant really tell if it is normal or if it is a carb issue that makes mine seem kinda choppy at low speeds. My kids ride this around the campground so it sees alot of 15 mph or less driving. I take it out on the trails and it opens up fine and runs good without overheating. I read in the manual that an idle to part throttle issue could be caused by the air pilot screw adjustment. I checked mine and it was turned almost all the way in! I looked in the service manual and the specs said 1 turn out so I set it there and it seems to be better, or maybe I just think it is. I run NGK plugs in it and never have a problem with fouling or blowing alot of black smoke, just the usual light smoke from the two stroke oil.

Is this just me or is this normal on a two stroke? Am I paranoid or is this just normal to have a gas hog when this thing is used to just cruise around the campground. I would like to have my kids drive the little Yamaha Breeze because its better on gas but apparently driving a small ATV isn't cool so they continue to burn my fuel.

Any help is appreciated!

Thanks, Mike

 

On the fan rigging,could be the radiator sensor has shorted out and po just wired the fan direct. I wouldn't run the fan constantly.The radiator sensor is bad about shorting out because coolant can get lower than it and it super heats and shorts out. You can pick up one at any auto. Item #8. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse The sensor on back of the head is for the hot light on the dash.You can do a resistance test on it when the engine is hot and cold. If resistance drops when hot,then the sensor should be okay. Just hook it back up.Anytime you you mess with the cooling system,open the 10mm bolt on the head to bleed any trapped air also. Located right down from the one wire temp sensor.Gas hogs.. Yes I've heard this complaint over the years from owners especially ones that had two stroke and 4 stroke atvs. 1 to 1 1/2 turns out is normal on the air screw. Plus all 400 carbs were bad on vibration causing frequent needle and seat wear. A cheap carb kit from ebay,etc may help it on low speed driving and performance. If a two stroke doesn't smoke I'd be worried! Even the so called "smokeless" oils are confusing.They just smoke a little less than some of the cheaper oils if everything else is okay.

 

Thanks Old Polaris Tech!

I guess I will just buy a new radiator sensor to make this work like it is supposed to.

As for the carb, I have rebuilt carbs before on small engines, but never on a two stroke atv. Is this pretty straightforward if I have the manual or should I let a pro do it? I am pretty mechanically inclined because I work on cars for a living and do everything else to my Xplorer by myself.

Don't get me wrong, this thing does smoke and the oil injection works properly. I just figured if it was burning way to much fuel I would see alot of black smoke and have a black sooty plug, which I dont. I know the carb does leak a little bit every once and awhile if it sits. The old owner always shut the fuel off....maybe this is telling me to rebuild the carb.

Thanks, Mike

 

Pretty straight forward on carb rebuilds.Carb kits are available everywhere such as on ebay and here also. Polaris Xplorer 400 Carburetor rebuild kit (SKU 03-407)
Plus a couple videos that might help on the Mikuni carb.

 

Thanks!

I guess I will order the kit and try the rebuild myself after watching the videos.

Thanks, Mike