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Discussion Starter · #1 ·
Well I finally got to ride my freshly rebuilt XLT Special yesterday. Engine was smooth, no bogs, great power throughout the range.

My question is this; at one point after I had been giving the kids rides for about 40 minutes I got on alone and on the way back across the field I gave the engine full throttle (had never been at full throttle before) for less than a second and the engine didn't want to take all the gas and kind of bogged down so I let off immediately. Ever since then the sound of the engine has changed. There seems to be more engine noise than before,almost a clattering sound, it's also louder when you get on it, but it still starts and runs good. I changed the plugs several times with no difference and I am still on the 50:1 tank. Do you guys think I hurt my engine or is this a normal thing?
 

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Do a plug reading, they should be light tan
Also, check your exhaust pipes to be sure they are connected tight or if anything is broken there.

Check compression, etc. as well
 

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engine "clattering" somtimes is the clutch. hopfully for you thats what it is.Please explain more what it did when you gave it full throttle.
 

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read the plugs, and tell us what the top of the pistons look like, espeically near teh edges.... You might just be imagining things, but maybe not!

-Dean
 

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I think I would take the exhaust manifold off and look at the piston .With the engine stopped rock the clutch back and forth and see if it makes any
noise.You have to find out what the noise is .You should get some one else to have a listen also .
 

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did you go overbore?(.020??)re-jet carb and adjust air screw/e-clip to match?? or, plugged exhaust ie...mouse nest?? that might cover the bog. as for the noise?? stuck weights, recoil rattle?? how were you riding "with the kids"? slow,low throttle?? and how did you break it in to start with??
 

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Discussion Starter · #7 ·
Just got back from up North put a 100 miles on it cause the mechanic listened to it and said just ride it and get the break in tank out of it and bring it back if it doesn't start to wake up. Well the break-in tank is out of it and it still is running poorly. Starts run, and idles ok, but has a hard time getting past 60. Lots of engine noise especially when hot, yes some of it is exhaust but that shouldn't stop it from getting up and going. The engine is .020 over with 3 new pistons and a new PTO bearing and I wasn't going that slow with the kids, just running it up and down the rpm range keeping it under 7500. Also up north I put in 5 sets of new plugs with no difference and it kept blowing antifreeze out the top of the overflow container. Compression is from 165 to 172. The guy who did the engine has it now and I will let you know what he finds. Thanks for your help, let me know if you think of anything else. I was thinking head gasket but would the compression be so good?

I checked with the mechanic and the compression was 145 to 152, sorry for the bad info.
 

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Discussion Starter · #8 ·
Oh also plugs looked good in color, PTO side fouls out quicker that others. And the weather stinks here, it's foggy and raining. 100 miles on the crappy trails around Cadillac and almost wore out new slides and carbides.
 

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Compression from 165 to 172???? Something wrong there, it's a little high.
 

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Discussion Starter · #10 ·
I just figured that was because the engine was barely broke in. I will find out if I'm remembering the numbers wrong.
 

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The higher the compression is, the better. But the more compression there is, depending on timing, you need to run higher octane fuel.

Anyway, if that's where the compression is, your gauge may be out too. I personally wouldn't worry about compression being TOO HIGH. It's LOW compression that people worry about. When things are worn out and leaking and stuff, compression goes down, not up. Worn rings, pistons, cylinder walls stuff like that makes compression go down. Not up.
 

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Hmmm, I had been breaking in a new engine on a 1990 Yamaha Exciter over the weekend, so I just started breaking in the new engine in my 1997 XLT SP last night. If you had said that you hadn't switched out your plugs I'd say that one of them was fouled.

Last night I was coming back up the lake and all of a sudden the sled starts running crappy. Couldn't get over 65 mph and was sputtering at low rpm's. I almost had a f'ing heart attack! Anyways the plugs I was running were old ones. Come to find out I fouled the center plug. Put new plugs in and she came to life.

Another thing that happend to me last year was I didn't hook up one of the throttle cables correctly so only two of the slides were opening. Sled would only get up to 50 to 60 mph. I checked the carbs and found the throttle cable that had come unhooked. Hooked it back up and was all set.

Hopefully your situation is something simple like mine were. But definately keep us posted as to what your mechanic finds, as I'd like to know for my own reference.
 

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Discussion Starter · #13 ·
Thanks TFIN I had the same thought and pulled all the slides and checked. Cables and springs still hooked up right. I'm hoping it's a plugged exhaust or something simple. I called the mechanic this morning and he said that it still turns over real smooth with the plugs out. PTO looks rich and other 2 plugs a little lean, but I told him those plugs only had about 5 miles on them. And the way it acts is like something is plugged up. When it started running crappy it happened all of the sudden and the sound changed so maybe since this sled was just sitting for a few years something came loose in the silencer or an animal built a nest in there cause it sure ran great for the first hour. Maybe just my wishful thinking, I will definitely let you know.
 

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XLTSP if you are blowing antifreez out the top of the overflow container I would say you have a blowen O ring under one of the heads. I have seen that before. It is pressurizing the cooling system. One of the O rings may have slipped out of place when the head was put on. Riley
 

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I would think that it would. I'm assuming when he's talking about the head O ring he means the head gasket. I can't believe that a brand new head gasket is blown out already, but I suppose stranger things have happened. Anyways if it is blown out, you'd loose compression which would equate to a loss in power. But definately keep us posted.
 

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Discussion Starter · #17 ·
I am so bummed. Just talked to Jerry the mechanic and my crank is out of index (twisted). I knew I had all the carbs cleaned and adjusted right, but now I wish I had made a mistake. He said it's nothing that I did some of these XLT's just do that. Anybody have a new XLT crank they want to give away? lol
I have a feeling that my snowmobiling is going to cost more than $1000 an hour now.
As usual I will keep you guys posted. Thanks for all your help and encouragement.
 

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Man.........that totally sucks!!! I've got to admit, I'm scared as he!! about my crank now. I guess there's no way to prevent it, and you never know when its going to let loose. Just ride untill it does I guess.

Has anyone heard of a 97 XLT SP or newer going 10,000 miles without crank trouble? I've got 6000 on mine..........I don't know.
 

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Discussion Starter · #19 ·
I'm not giving up on sledding yet, but I am definitely thinking of a brand change if owning a Polaris is going to be this expensive and discouraging. I've heard Yamaha's are very reliable.
 

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Tfin you are right I was talking about the head gasket which is 2 o rings if I remember right on that motor. It's been a couple of years since I have been into one of those motors. Riley
 
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