Hey all. This is my first post to these forums. Anyway, I have a '95 Polaris 400l 2x4 utility bike that quit running on me the other day.

I was riding the bike over to my uncle's place a few miles away when it just up and died on me. It seemed to be running decently up to that point, and there was no warning when it quit. It was just like I had turned off the key or hit the killswitch. I hopped off and tried to start it back up but couldn't get anything.

After getting it back home, I checked a few things, and this is what I know so far:

It is getting fuel.

It is getting spark at the plug.

It has a brand new plug in it.

There is gas in the tank and oil in the injection tank.

The battery seems to be fine (it still powers the lights, and trying to jump start the bike from a car battery didn't change anything).


I am absolutely stumped as to what could be wrong with the bike. Anybody else know what could be wrong?

 

Is compression good,at least about 100 psi? Could have seized,lost compression.

 

I had a sheared flywheel key do the exact same thing. if you look at the flywheel with the center at eye level you should only see one spot where the key is. if it looks like two or more then the key is sheared causing the flywheel magnet to be in the wrong place at the wrong time. pull it off clean it up with some super fine sandpaper just to get any burrs off, replace and do a wheelie.

 

Does anybody have some instructions as to how I get to the flywheel? I'm not completely mechanically retarded, but I'm just not really familiar with the layout of this bike. Thanks in advance.

 

First remove all of the bolts from your pull starter and theres your flywheel. Here are directions if the flywheel has to come off.

Since just recently performing a flywheel removal, I will recommend the following:

A six point socket for the flywheel nut and buy or borrow a decent electric impact gun. Makes simple work of this, because believe me when I say you will need it. If you try removal without, you will more than likely end up damaging something.

Then you need a flywheel puller that uses three bolts. Should be able to find a new puller for $20-30 bucks. These should come with an assortment of bolts with different threads.

I had to use the electric impact both on the nut and on the puller and it made the job simple. I can't stress enough how important the electric impact gun is.

I hope this helps. My two cents.

 

Okay let me clarify a few things. I had the carb off because the bike was not running right a while back. It would start and run but wouldn't rev properly. We eventually discovered that it was the reverse override switch somehow interfering with the engine even when it was in the forward gear. The fix was simply to push the button a few times and voila it was working fine again. However, before we found that out, we thought maybe the carb was messed up, and so we took it off to clean and check it.

Anyway, I haven't had much time to look at the four wheeler since I posted this topic, but I can tell you that it is for sure getting spark at the plug. It seems to be getting gas as well. I was going to run a compression check on it, but it is impossible without removing the gas tank, and I haven't had time to do that yet. You can definitely hear the piston still moving up and down through its cycle when you slowly pull the recoil.

The starter has had something wrong with it ever since I bought the bike. Sometimes it would kick in and other times you just hear a loud click. However, as time has went on, the starter has kicked in less and less frequently until now when it never does (you still just hear the click). Anyway, I've basically always pull-started the bike. However, before it died on me, it was like the piston would be moving through its stroke, so you would pull it once and it wouldn't pull all the way out (and if you did try to pull it hard to start it it would just about rip your fingers off when it stopped midway through) but the very next pull it would and would start. Ever since it died on me, though, it has just pulled out the same every time. There is no hard pull anymore. I hope I've typed this understandably; it's kind of hard to explain. Anyway, I thought maybe this might be a clue to you guys what could be wrong with it too.

 

sounds like you either burned a hole in the piston..very possible if you messed with the carb and ended up changing the air/fuel mixture causing it to run too lean. or it broke a piston. if it has the original polaris piston in it, it could have broke but im gonna go with a hole in the top of it. first do a compression test..if fails compression then take the head off of motor to see which one it is