I have a 2003 rmk trail 550. It had been running bad. I put new jets in the carbs. I put in 210s. I think 270s were what I replaced. It was running great. Starting good ... I was climbing a hill going to get stuck so I turned and started down. It died going down the hill and would not start. It has spark and it has fuel. I had to tow it out. Tried to start it and it pulled really hard but finally loosened up and pulled ok. Again, spark and fuel but doesnt even come close to starting or firing. Did I blow my motor? How can I check? Did I crack my cylinders? Not sure what to do. Thanks for any suggestions and help.
2003 Trail RMK 550 died climbing a hill
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Check compression. Those 550s from that time are known to go BOOM at any time as it wasn't a good design as they would overheat very easily. You went down 6 sizes that could have leaned it out as well. You jet for elevation and temps and that might have been too much.
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Going from 270 to 210 is a HUGE drop in fuel. Were you following a jetting chart for the temperature that day and the elevation you were riding?
Take a compression reading, my guess is also that it leaned out and you have piston damage. Pull the carbs and the exhaust and look at the pistons, my guess is they are scored big time.
Take a compression reading, my guess is also that it leaned out and you have piston damage. Pull the carbs and the exhaust and look at the pistons, my guess is they are scored big time.
Thanks for the help. I was told by some guy to go to 210. I wasnt smart enough to check into more than that. The motor didnt make a large noise. Do you think I can just replace pistons or will I need new cylinders and possible crank? Thanks
Most likely if they pistons are scored then you can send it in to be bored out and with new pistons/rings as well. SLP, Indy Specialities and US Chrome if you send the jugs in and buy pistons from them they will match them up for you. If there is chunks missing from the pistons then you need to tear it down completely and make sure nothing is wrong with the crankshaft and get out the pieces which means a full gasket kit with seals. Those 550s are very touchy to begin with so even the slightest change will make a difference and going down 6 jets yeah it could cause those issues. Check compression and if you can take a flashlight and look in behind the carburetors to see if any scoring if you can't see any then pop the cylinder head like dan my guess is there is scoring on the cylinders are at least one of them which at that point you replace both. Hopefully you can get away with just boring and new pistons/rings. Then after that jet for elevation/temps for your area per Polaris. Check the service manual in the sticky link dan provided in the Polaris forum. He put up a link I found with service manuals and it has all that information in there and there is a 2001 and a 2003 in there.
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Sometimes learning is spendy, especially when it comes to jetting. I learned to pay attention to that after buying a sled and being told by the owner that it was jetted for high elevation... I was running at lower elevations and when zooming across a big meadow, my two cylinder turned into a single cylinder. Jetting too lean burned a hole in the top of the piston. Oh well, that sled was a big prompt for me to learn a lot more about sleds so I didn't do that again!
Hey guys,
I checked the compression. One side 85 and bled down to 60 in 1 minute. The otherside 70 and it held it. I would think I should start on this and maybe even run. This thing only gets to about 95 when it was running good. Do you think something else is wrong with the sled. I know I have spark and my plugs come out wet after a few pulls. Any suggestions or thoughts? Thanks.
I checked the compression. One side 85 and bled down to 60 in 1 minute. The otherside 70 and it held it. I would think I should start on this and maybe even run. This thing only gets to about 95 when it was running good. Do you think something else is wrong with the sled. I know I have spark and my plugs come out wet after a few pulls. Any suggestions or thoughts? Thanks.
I checked the gauge on another sled. Seemed to work fine about 110 on another old sled. I pulled the carbs and exhaust and couldnt really see. Just wondering if based on these compression values (85 then down to 60 in 1 minute and 70 but held it) if you could tell if it needs a rebuild or if there is something else wrong. Thanks for your thoughts.
It's in need of a rebuild you leaned it out way too much. Compression needs to be at least 110 for it to be running good and after a rebuild it isn't shocking for some to see 130 or above but 120 is normal in many cases as well. Time to yank the engine apart, most likely you are going to find the cylinders scored and on that one you will need to have it bored out 0.10 and get pistons that are like that. Nice thing is is US Chrome, Indy Specialties and SLP if you have them bore it and buy the pistons from them they will match all those up including ring gap usually.
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