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Discussion Starter #1
I was out starting my sled the other day, and as soon as i pulled the rope, actually the second pull, it backfired and then almost sounded lie a single cylinder dirt bike motor. Could this be a blown cylinder? Im really nervous because I dont have th emoney to fix it and we are trying to sell it. O, its a 99 XC500SP. I have not even tried to start it because I am afraid to. What should I do. I NEED HELP NOW!!!!!!!!
 

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The only thing to do is pop off the head and take alook at it. And if it is, good luck, because I currently have 2 blown jugs and topend and holy crap is it expensive to replace. Just try and find a used jug for cheap (still expensive) at a scape yard or on ebay.
 

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Non burnt gas will make a backfire, or bad jetting, bad timing... This is not telling you that the engine is blown! Bad compression can make backfire too. Check the compression first. When you said it sound like a dirt bike, what are you trying to say? Did the backfire make the muffler to split from the pipes or what! I will bet that the sled as been parked for a while and the case had too much gas in it, and make the engine to backfire! But seriously, you don't have to be afraid starting it again! Hope it helps, let us know. [;)]
 

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Originally posted by mackinsaw
[br]The only thing to do is pop off the head and take alook at it. And if it is, good luck, because I currently have 2 blown jugs and topend and holy crap is it expensive to replace. Just try and find a used jug for cheap (still expensive) at a scape yard or on ebay.
Before pop off the heads I will look something else like comp, gas leaking in the case, bad jetting and such... it will cost less than disassemble the whole thing!
 

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Discussion Starter #5
well, going back to the dirtbike thing, i sounded like only one cylinder was running, you know when a 2 cycle dirt bike is running, it sounds different than a sled. Thats what this sounded like. i will check the compression tomarrow when my dad is at the foot ball game so he doensnt find out. What is the process of removing the head to replace the head gasket in case i blew that. I knwo compression should be around 100-120psi on both cylinmders, correct. O, and when it was idling, i had trouble keeping it at 100 rpm, it usually idles at 1500rpm. man, this cant be good. I hope you can understand my panic.
 

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Boy do I under stand your panic!! God dang that sucks. Well if your dad finds out he finds out. It has to happen sooner or later, and he probly knows some trouble shooting tips and can help you work on it. I would get on it ASAP. For one jug in town it costs like 325$ So whatever happens Its going to cost slot of money. It could've even been a piston skirt or something. So whether you just need a head gasket, its going to cost money and your dad will find out. Good luck bro.
 

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Do both cylinders have spark if only one is firing that will make it f up to.
 

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Maybe you blew a hole in your pipe from the backfire. I did the same once and the sled sounded like it was running on one cylinder.

Easiest way to check your piston is shine a flashlight down inside the plug hole. Or pull carbs/y pipe and have a look inside.
 

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pretty much everyone has given great advice, but man dont panic yet! if its been sitting you could have had some gas filling bottom end, old fuel sitting there, this list can go on forever. when it backfired, may have blown the exhaust loose, or maybe fouled that plug right out. DONT start pulling s#!t apart. start with simple things, check the bore with a light, check the plug, for fouled or engine parts! check your compression, check for good spark. all the things that dont cost anything. as soon as you pull the head off, now your buying a gasket set. i hate when people tell guys to start by pulling stuff apart. its usually something simple. start with the basics before you panic. besides if the cylonder is bad, look at the bright side, its not 3am out on the trail somehwere. youre at home.
 

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Discussion Starter #10
Well, thanx for all the advice, I will check tomarrow after school after my da leaves, il say im taking the starter solenoid off the XLT which my dad wanted me to do. lol. Hopefully i just fouled out the plugs. But, if the gasket is blown or there is no spark, how much is it going to cost, for both fixes at different times. So one at a time. I know how to do the gasket i think, drain coolant, remove head, replace gasket, re-fill coolant. correct?? but I have no clue on how to fix the ignition system.
 

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its not likely an ignition problem, if you dont have spark you more then likely just fouled a plug. keep us posted with what ya find out. remain calm, dont get your panties in a bunch. should be a simple problem. no matter what it is youll get thru it. welcome to the world of sleds. gotta pay to play. just like women!
 

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did you clean the carbs if your running on one cyc it might be a dirty carb it dont take a hole lot of dirt to plug the jets it dont cost but a can of carb cleaner maybe $3.00 and some old telephone wire to clean the jets out good luck
 

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Alright Bro, First things first, Calm down. If I paniced everytime my sled backfired I would be insane. I have ran a sled on one cylinder for a long time, not a great thing, but, not fatal, especially if it was only for a minute. Like everyone already said, check compression first, you can do this the same time you check the plugs. Pull the plugs and put your finger over one of the holes (unless you have a compression tester), and turn the motor over. if it can push your finger up a bit, you have compression, do the same on the other side. Put new plugs in it. Once a plug soaks up fuel, no cleaning can save it, it is always better to use new plugs. Also, check to make sure no one has jacked with the idle on that carb, I rebuilt my motor last year, put it in and it was only running on one cylinder, I sweated for a second, then realized that someone has screwed the idle adjuster all the way out on that carb. Also, you probably have some crappy gas in it, if it is about empty, pour some new gas in it, if it has more than an 1/8 of a tank, suck the old stuff out.
 

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Discussion Starter #14
Thanks for all the help guys, when i get a chance to go out and check on my baby again between school and extra curricular activities, i will. I only got nervous because it backfired and sounded wierd, it still sounds wierd when i started it wwith my friend there. Ill get back to ya'll soon!
 

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Discussion Starter #15
Aight Guys, First thing I want to say is that you guys are AWESOME!!! I couldnt have done it without you. All that happened was my mag cylinder (i believe that is what is called, not clutch side) plug was fouled. I changed it out and she started right up. I was so relieved, now i have to figure out the problem with the XLT, but my dad knows about that one. WHEW. YOU GUYS ROCK MY...PLUGS!!!
 

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HAHA ^^ they told you not to panic because it was probly something stupid!!
 
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