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Discussion Starter #1
Ok, here it goes:

I've been riding a buddies sled all season while I've been fixing my 97 XLT SP. I had to replace the entire chain case, cover, and everything in it. Chain let go last year and shattered everything.

Anyways, finally got it fixed on Sat and everything seemed to be working fine, at least the parts I worked on. The big problem arose when I got it out on the lake and found that the sled was only doing 60 mph at 7000 rpm. When I hit the gas, it starts to spool up good untill about 40 mph then you can hear the rpms start dropping and like I said I only get 60 out of it.

My thinking was that it was clutch related. Maybe needs to be cleaned, adjusted, etc. If you hold the track off the ground and give it the gas, it spools right up to where it should be....sounds right too. So just for the hell of it, I decided to check the plugs. They are BR8ES R's that were only run for one weekend last year. The right cylinder's plug looked a little too light in color, the middle looked perfect (cardboard brown) and the left was black and wet. So I put brand new plugs in it, ran it across the lake and back and checked em again. This time the right and middle plugs looked fine, but the left one looked as if it had never even been burned, and was wet. So I'm thinkin no spark....I hold the plug on a piece of metal, and check the spark...lo and behold, there IS spark. So its getting gas, and aparently its getting spark, but its not burning???

When I had the sled apart I cleaned all the carbs, jets, etc. The left needle in seat MIGHT need to be changed, the bowl was full of gas, when the other two only had gas in the drain tubes. Haven't done a compression test, would bad compression in that cylinder produce those results? The sled idles fine, and seems to run fine, except for the lack of top end power. So my concerns are clutches and that left cylinder.

I am going to bring it to a dealer tomorrow. If this was the summer, I'd have the time to do some of my own diagnostic work on it. But with there only being like 2 months of riding left, I want it fixed asap. I was just curious if anyone out there might have any thoughts or ideas on this???????



1997 XLT SP 600
 

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In any of the triples I've had if one cyl. is not firing you are'nt going any where at 60 mph. So It sounds to me like you may have bigger problems. Maybe a crank seal
or a piston/ring problem. there is always a chance that the carb on that side is feeding way too much fuel. maybe the main jet didnt get completely tightened or something easy like that? I hate to even say this but, the fact that it is ok on the stand under no load makes me wonder if when it is under load, if the crank bearing is worn and that allows the seal to be deformed and not seal around the shaft. This time I hope i'm wrong! Good luck.
 

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I would definately check the cyl for compression balance, then address the carb situation, like hotrod said.

Have you moved the engine around on the motor mounts?? Usually for the chaincase you wouldn't touch the clutches or the motor, but the sensation of running right up to 40 mph and then struggling, sounds like a clutch alaignment issue. But do the other checks also.

GL and keep us updated.

(o;

DNO.
 

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Discussion Starter #4
Nope, never moved the motor. My first impression was clutch issues. But with that left cylinder producing spark, and the plug looking wet and unburned......I don't know. Even if the compression was bad in that cylinder, wouldn't I at least see that the insulator on the plug to be a little brown. Would too much fuel being allowd in produce this? Like I said earlier, it idles and seems to run fine, no funny sounds, just no top end.

In all honesty, it doesn't seem to get up to 60 the way I think it should, but when it does get there, you can really feel the power drop off, and hear it as well....not running rough, just not spooling up like it should.



1997 XLT SP 600
 

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I'd check the compression across all 3, and write the numbers down. If anything else, it will give you some handy info.

Then go on to the carb.
You may have a weak seal or ring that cant keep the pace when under load, maybe like hotrod said.

I'm not real familiar with the newer Polaris carbs, so I cant help much there.

GL

DNO.
 

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Which cylinder do you think you are having problems with? Farthest from the clutch? Did you shine a flashlight into the cylinder to check for a hole? When you have this engine rebuilt make sure the case is drilled, a design flaw does not allow proper lubrication in that cylinder. I have the same sled, $1000 spent last year to rebuild and drill the case.


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Discussion Starter #7
Yeah, I could see the piston through the plug hole, didn't see a hole in it (the one closest to the clutch is the one in question).



1997 XLT SP 600
 

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Discussion Starter #8
Update:
When I got home last night, I checked and found the left carbs throttle cable had come undone. Loss of power solved.

Unfortunately I also found that about 1/4 cup of gas had leaked out from some where onto the floor under the belly pan. I had left the gas valve on, but that shouldn't of mattered. Bad inlet valve and/or floats in one of the carbs? Tried starting it, but flooded out every time, all three plugs soaked. Drained the bowls in the carbs and tried to start again with the same results.

I'll check tonight to make sure none of the choke cables are stuck, any other ideas? Thought I had heard some where that there was a bolt some where under each cylinder to drain gas? Anything to that? Any help or ideas would be appreciated, thanks.



1997 XLT SP 600
 

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When my 700 flooded that bad one time, all I did was take out the plugs and pull it over untill all the gas stopped coming out of the engine. After that I heated up the plugs, and it started, it wasn't easy though. There wasa whole pile of gas that came out of the pipe and there was a mess everywhere. Since then, this problem has been fixed.


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Discussion Starter #10
Did you take the pipe right off (not the head pipe) when you did this?



1997 XLT SP 600
 

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97 XLT SP should be running a BR9ES plug with no resistor. Also, under the pipes almost at the bottom of the engine, there are three small bolts. Take those out, take the plugs out, and pull it a bunch of times, this will clear the gas out of the engine. This is most efective with the carbs off also. Check and clean your jets and make sure the needle jets arent sticking.



Edited by - skrplyr23 on 06 Feb 2002 10:39:32
 

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Discussion Starter #14
Ok. I'll give it a try tonight and let you know what happens. Thanks.



1997 XLT SP 600
 

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Discussion Starter #16
I always thought it was the last R (BR9ES R) that stood for the resistor....but I could be wrong.




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BR8ES = Resistor
B8ES = No Resistor

Resistor or not, it doesn't matter on old sleds, u can use resistors. On new ones though, you probably have to use a resistor.



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