Hi all.

I'm new to this forum and to ATVs. I just bought a well used 1994 Polaris Xplorer 400 and was headed up a dirt road when I heard a pop and a hiss and then seemed to lose all compression in the engine and it shut down. It turns over but never started back up. Here are my questions:
1. Did I blow a ring possibly, or might it be something simple?
2. What should I expect to pay for a new ring/piston if that is the case? What else should I get done if I have someone go to all of that trouble.
3. Should I use the local giant Polaris dealer/service or go to my neighborhood shop that works on any ATV?


Thanks for any help offered!

 

GR8Dane, Welcome.
Do you still have spark when its turning over???????? If yes then -----------------
What ya need to find out 1st is how much compression ya got if any cause you say its turning over.
Pop then a hiss you say? I've never had a Hiss unless the head gasket possibly blew and it would make a "POPPING" sound before the hiss, I GUESS?

Start with a compression test first.....115 PSI is the so called service limit on my 2000-400cc 2-stroke. It will still run pretty decent under that number until around 107 and probably wont run at all under 100 or not very good if at all!

How was it running before the mishap GR8? Sputtering? Backfiring? Hauling A$$? Smooth? Rough? Barely?

Piston/Ring kits are usually under 100 beans for a nice Wiseco but ya need to see if it needs to be bored bigger to gain compression back and clean up the cylinder...
Others on the forums will follow with addresses and names of the "ELITE" jobbers on the Polaris Forum...They know who they are, that can help your machine perform once again.

But First MORE INPUT is needed from your end.........hope the news isnt bad.......get back with more info GR8Dane and again welcome.

HAMMERING HANK..(DUG)

 

first of all, is it turning over really easy? If it is the skirt on the piston probably broke seeing as every 400 explorer does that..... One of the easiest ways to check compression is to take off the spark plug obviously, but just put your finger over the hole and turn it over, If it blows your finger off it is probably not that. but if you can hold your finger over it while turning it over your gonna have to start ripping and tearing.... Also, if your skirt broke chances are that it blew a hole through your block to. so look around under the carburator area and see if maybe there is a hole.......... A .020 Wiseco is only $100 Good Luck man...........

 

Thanks for the quick response and suggestions. Here is some more information:

How's the compression?
I'll have to see if I can test out the compression one of these next nights when I get a chance. I probably ought to splurge and get a real tester, but may use my finger as a start.

How was it running?
The machine was starting and running really well and strong except for some occasional hesitation at high throttle... flying along and then it would die, then kick right back in with a few pumps of the throttle... all within a second or two. When I first got it I put in some octane booster in the first tank, (suggested by a friend) and it cleared it out for a while, but then came back 2 tanks later. I was just starting on another tank with some octane booster again when the incident occured... Man, I hope I measured it right!!!

Is it turning over easy?
Yes, really easy. It just doesn't fire up. I pull the cord and it pulls really easy now, not the usual rip my fingers off stiffness.

 

If you have the AUTO ZONE parts people in Utah you can borrow a compression tester from them for nothing,(very small deposit, returned to you when you return tool).

A compression tester will only cost 20-30 dollars from almost any auto parts store, you dont need anything fancy.

You stated hesitation occasionally at high throttle. Were you at high throttle when this happened?

When you crank the engine over do you hear any air sounds escaping from areas of the case that should'nt be cause, if you do, something let go and punctured the case! If not you may still be in good shape for the fact that it even turns over!

If you have no compression you may have blown a hole in the piston being you stated the high speed hesitation and how much easier the engine turns over now, without ripping your fingers off..

----------------------------------> Let us know. GOOD LUCK

 

I think you should replace the spark plug..............LOL BR8ES hahaha

 

Hey HammerinHank, what part of michigan you from?

 

MuDdiN400.......I'm in Kalkaska........Between Traverse City and Grayling

 

Well, MuDdIn400 had the correct fix: "I think you should replace the spark plug" After finally getting a chance to look at the problem, it turned out the spark plug had somehow wiggled loose and blew out of the block. I was hanging by the plug wire over the front suspension. I cleaned it off and put it back in, torqued it to 17lbs and it fired right up.

Talk about a cheap fix for what I thought was a blown ring.

Thanks again for all of the help!