About a month ago, my buddy Jeff had the cam timing on his 850 jump on startup while down in PA.. Yesterday, mine does it at startup. Jumped time, wont start, but after it jumped, there is a loud clicking when it turns over on the starter. I think a valve is touching a piston at or near TDC. My other buddy Tom, who is a Harley Davidson mechanic and works on other brands as well, thinks its the chain tensioner making the noise.

So, some questions,

Has anyone else had cam timing issues with the 850 engine?? Does anyone know if the 850 is an interference design?? Jeff's quad has 650 miles on it, mine has 512. It is well maintained, and has always run well. Any issues with the cam chain stretching?

Lucky for me, I have my Kawasaki Prairie 300 so hunting season hasn't been ruined. (It's more than a mile from where I park to where my stand is...I'm not walking it with all my cold weather gear on, I'd be a sweaty mess)

I'm tearing into it over the winter, I guess we'll see how bad the damage is then. Still pisses me off.

 

Jeezzzzzz... 500/600 miles with issues like this with these wonderful machines that everybody is bragging about. What a shame.

Anyhow, my buddy works on all brands of quads in his shop. He's been seeing more and more XP's come in for issues as they get some miles on them. I "think" I heard he mention one that had a bad cam sprocket (missing a cog) or something like that. I'll check with him the next time I see him.

In the meantime... good luck.

 

This is the first I have heard of this issue. Please do keep us informed...and Good luck with the fix.


biz

 

Well, I had a chance to stop at my buddies shop this morning. He was working on a PoPo on a Sunday morning, so I won't repeat everything he said, as it may offend some PoPo guys, and would get censored on the forum.

Anyhow, his first question was "What makes you think the the timing jumped? What is it doing, or not doing? There are other things that can make it act like it's out of time."

He said he doubts that the timing chain could stretch within 500 miles.... but anything is possible.

If it is the timing, he's more inclined to think it's the shear pin. Although, he said it could be something internal that could get real nasty and expensive.

Also, he said it is an interference system. So, if indeed it has jumped timing, there's a risk that you could do damage to the valves and/or pistons if you mess with it.

 

I'm gonna answer these backwards, so bear with me...

First of all, I am a professional mechanic. I maintain and rebuild refrigeration compressors ranging from 5 to 11,500 HP.. recips, screws, and centrifugals, so I'm doing the work, or put another way, I'm messing with it. I'm experienced rebuilding Ford and GM engines as a hobby type thing, and have already had an 850 engine apart with Big Jeff (My name is Jeff too, but Big Jeff has about 75 lbs on me, and I go 250, so he's Big Jeff) as we had to re-ring his because it sucked dust for a few rides due to a bad airbox boot clamp.

It could be a shear pin or a key, but I haven't pulled it apart, and likely won't until after deer season is over.

I doubt the chain is stretched, but as your buddy said, anything is possible.

The engine turns over, but does not run.. There are more than the normal valvetrain noise going on. One of the cylinders is trying to fire, but the other is definitely not trying to fire. The sound coming from the exhaust is not the even, 270 degree sound it used to make. The more I think about it, the thing sounds like I've broken a valve spring or maybe a rocker arm. I don't want to turn it over anymore though, as that loud ticking makes me think I'm touching things together that shouldn't be touching. I suppose we'll find out in a few weeks.

Incidentally Bossman, what do you ride? Just curious....

I've owned two Polaris ATV's, and this is my first issue beyond recall, or operator created problems (read that as me breaking things). I'm not stupid either, and know that Polaris has more than It's share of quality control issues. I suppose it was maybe a matter of time.

 

1. I believe that's what he meant by "messing with it"... continuing to try to start it/turn it over.

2. Not a PoPo

Didn't know you had it all under control... thought you were asking questions for some help... tried to give you some. I won't make that mistake again... good luck with it.

 

Tear it apart and letus know, real curios

 

Hey Bossman, no offense meant in any way. I think sometimes written word gets taken wrong. I was just giving a background of myself to indicate I wasn't an idiot when it comes to mechanical equipment. (I am an idiot in so many other ways, however) You in fact answered my biggest question (the interference design), which tells me not to mess with it any more until I pull it apart.

Maybe I came off chippy because I'm still pissed off. Maybe it was because you were taking admittedly mild jabs at Polaris, on a Polaris forum, while keeping us in the dark about what you ride. Either way, I'm not a brand snob, and I don't care what you ride..

I'm just a cocky sarcastic redneck, and I'm sorry if I ruffled your feathers.

 

Not sure on any internal issues and havent really heard of any on your machine. I know around here on the 2009 850 it was real common to foul out one or both spark plugs and wouldnt run or run right until you changed them. Mostly happened if you started machine and shut it off before it was warmed up. From the noises sounds like you have something more serious but just letting you know what I've ran into.

 

Changed to NGK plugs on mine no problems since, # is ILZKAR7A10 #6043 AS stated . dont know if thats the problem or not,