Just finished engine rebuild.

[pernikm]

sounds like detonation. Did anyone mill the heads? Is the squish band still correct? My guess is yes...but there are previous owners...Don't forget the good old fashioned kinked or plugged gas tank vents. Make sure you have the correct plugs in. Use the factory specified plugs. There are minor differences in heat ranges that can make a difference when you are on the edge.

 

[diggerdown]

With your piston discription, Dale was right about the octain being too low. Question is, why? Have you added compression or timing? Turning the oil up will not help with deto. Have you checked the actual temp of your coolant? You could have a bad thermostate or sensor. Your timing could be advanced too far and that would explain the overheating at an idle and the deto. A bad or improperly adjusted tps could change the timing enough to do this, if you are already running on the edge.

 

[Klimbing Kitty]

Still sounds like one of your 4 o-rings is squished

 

[kane13]

Well you know your temp light works, i would wait till you have snow and cooler temps to run it much more. If you are sure it was put back together properly just wait for winter now, was it overheating when it burn't down? checking the temp light is part of pre-delivery inspection it should come on after about 5 mins. Maybe check your compression if that is good your probably ok, and next time you have to rebuild buy or go to library and take out a book on engine failures they have many pictures of different pistons and explain why they failed then you can find the route of the problem. JMO

 

[Burns1980]

When you say "pot mark" do you mean it was indented?
Sounds like detonation from what you described.

If it were me I would look into it more... You should be able to run a STOCK sled with 87 even at sea level.
The owners manual does not state different fuels for different elevations.
What fuel do others in your area run?

They all run 87 but they use different sleds. Could incorrect use of the Fuel Designation Connector cause this type of problem?

 

[Burns1980]

sounds like detonation. Did anyone mill the heads? Is the squish band still correct? My guess is yes...but there are previous owners...Don't forget the good old fashioned kinked or plugged gas tank vents. Make sure you have the correct plugs in. Use the factory specified plugs. There are minor differences in heat ranges that can make a difference when you are on the edge.

The heads were never touched according to the previous owner. Not sure what you mean by squish band. I did not check the gas tank vents. I use the factory recommended plugs.

 

[Burns1980]

With your piston discription, Dale was right about the octain being too low. Question is, why? Have you added compression or timing? Turning the oil up will not help with deto. Have you checked the actual temp of your coolant? You could have a bad thermostate or sensor. Your timing could be advanced too far and that would explain the overheating at an idle and the deto. A bad or improperly adjusted tps could change the timing enough to do this, if you are already running on the edge.

According to the previous owner, he never made any mods to the sled. He said the timing was never messed with. The only thing it seems he messed with was the oiler. Where is the thermostat located? tps?

 

[Burns1980]

Well you know your temp light works, i would wait till you have snow and cooler temps to run it much more. If you are sure it was put back together properly just wait for winter now, was it overheating when it burn't down? checking the temp light is part of pre-delivery inspection it should come on after about 5 mins. Maybe check your compression if that is good your probably ok, and next time you have to rebuild buy or go to library and take out a book on engine failures they have many pictures of different pistons and explain why they failed then you can find the route of the problem. JMO

It wasn't overheating when it burned down. The compression is good.

 

[Killerk]

They all run 87 but they use different sleds. Could incorrect use of the Fuel Designation Connector cause this type of problem?

I assume you are talking about the ethonol plug?
If so, not unless you were running ethonol fuel with the connector in the other position.
Not sure on newer models, but I beleive the laydown 700 was a 3% increase in fuel across the board with the ethonol plug disconected.


If the heads have not been touched, the squish should be fine.
It is the measurement from the top of the piston to the top of the combustion chamber at the outer diameter of the head at TDC.
You can check with a large piece of soldering wire down the spark plug hole, rotate the engine to crush the wire then measure it.

If you don't find anything, then like others have said, wait till it snows, go up planning on road riding and stopping often to check plugs, water temp, etc.
So you build some confidence before you really start loading the engine.

 

[kane13]

I think when he said the squish band he means the two o-rings on each head you have to be carefull while putting them in and installing the head make sure you used new ones.

Also make sure you go through the proper break in procedures, and if you are worried about oil consumption its easy to test just fill both tanks (oil and gas) and measure after you have rode a while, but this too has to be done in the winter. Take some extra anti-freeze, oil, and gas with you when you go, the fact that the oiler has been played with kinda worries me but all you can do is test it, replace it, or delete it all together. Also your thermostat is located at the inlet on your water pump i would only look at that after you do the other things mentioned or you will have to drain the cooling system again but don't count it out as the possible problem. also it never hurts to clean the air box out sometimes debris will build up in there and it could get through into cylinders especially if it was stored outdoors in a dusty place, there is a lot of reasons why this engine may have failed and without knowing the history it is hard to tell why, this is why i like to buy new but i understand thats not always possible. Good luck!!!

 

[Klimbing Kitty]

If one of your O-rings is squished it will blow hot exaust right into your coolant lines. It will overheat really quickly and your heat light may or may not come on as the circulation gets screwed up as well. When it overheats does it blow out the overflow? and is your rear heat exchanger not getting very hot?

 

[94fordguy]

OK, this is the first time I've ever taken a wrench to a sled and it was a major repair (for me anyways). I had to replace 2 pistons and get both cylinders honed. I got the thing running and it sounds normal but after about 5 minutes I get the overheating warning. I guess I'm not quite sure what would make it overheat unless I'm running too lean? I adjusted the oil arm (I'm not sure the technical name for it, but it's hooked to the throttle) to stock settings as before it was about 3 turns off of the factory setting so I can't see that being the problem. Any help would be great. Thanks in advance.

Roll the sled side to side while running to knock any air blocks out. It may also be normal, 5 minutes with no snow on the exchangers will overheat just about any sled.

I know Cats only have a light and not an actual gauge to look at, but I believe you have nothing to worry about. As winter Brew said, you aren't getting any cooling on the heat exchangers. Idling a sled for that long in the middle of summer time it is definitely going to overheat in short order. My buddy just got done rebuilding his Polaris and while doing a few heat soaks of the motor and making sure everything is running and sounding good, we observed that the temps would climb to about 160* in about 5 minutes with a combination of idling and light to moderate throttle use. Considering it is 90* outside and nothing to cool the exchangers, what else do you expect. Come this winter if you still have heating issues and your cooling system is bled correctly (it sounds like you did it right elevating the front of the sled, cracking the bleed screw, and refilling the bottle as necessary) then you will have something to worry about as far as that goes.

my $.02

 

[Burns1980]

If one of your O-rings is squished it will blow hot exaust right into your coolant lines. It will overheat really quickly and your heat light may or may not come on as the circulation gets screwed up as well. When it overheats does it blow out the overflow? and is your rear heat exchanger not getting very hot?

The heat exchanger does get hot. If you mean by overflow anything comming from the head then no nothing is comming out there. I did make sure that the 0-rings were in place when I placed the head on.

 

[Burns1980]

I know Cats only have a light and not an actual gauge to look at, but I believe you have nothing to worry about. As winter Brew said, you aren't getting any cooling on the heat exchangers. Idling a sled for that long in the middle of summer time it is definitely going to overheat in short order. My buddy just got done rebuilding his Polaris and while doing a few heat soaks of the motor and making sure everything is running and sounding good, we observed that the temps would climb to about 160* in about 5 minutes with a combination of idling and light to moderate throttle use. Considering it is 90* outside and nothing to cool the exchangers, what else do you expect. Come this winter if you still have heating issues and your cooling system is bled correctly (it sounds like you did it right elevating the front of the sled, cracking the bleed screw, and refilling the bottle as necessary) then you will have something to worry about as far as that goes.

my $.02

Yea you are probably right because I was running at about 6000 RPM for about 2 min.
When you say "cracking the bleed screw" you are talking about the oil right?