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Discussion Starter #1
i have 2005 sportsman 500 H.O i am working on for a friend. he was riding it and it blew the plug out of the head did not take any threads with it so im thinking it was just loose and worked it self out. after that it will not run i finally got it to start after a while of messing with the throttle. if i time it just right i can i can get it to start have to have it at W.O.T to keep it running it only runs at aout 300rpm will not rev up as soon as i let off the throttle it dies and backfires out of the carb. i have tried everything i can think of. please help im beating my head against a wall with this thing. than you in advance..
 

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Welcome to the board!:med:
 

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Discussion Starter #4
i have checked timing a hand full of times seems right on. unless it is possable for it to be 180 degrees off and still try to run?
 

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Have you checked compression? ETC switch in throttle housing, or maybe the carb slide is stuck and won't lift or there is a tear in the diaphragm.
 

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Discussion Starter #6 (Edited)
ok after checking the timing again this morning for the 100th time it is right. i finaly decided the pull the cam found that the lopes are with in spec. but found a pretty nice grove wore in the exhaust rocker where the decompression ball rides. also the desompression lever that slides in the end of the cam is wore down on one side where the ball drops out of the way when engine is running. i am wondering if if the ball is getting hung up in the decompression position not letting enough compression out cause of the grove in the rocker causing my hard start issue. but letting out just engough compression that when i get it to start it wont run right cause its letting out just a lill bit of the compression when its running. does this make any sense to any of you guys ???c
 

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Discussion Starter #9
i have no clue why i was getting a variable in the compression was running the 50 to 80. pulled the decompression lever out tested the compression was at 125psi. put lever back now i am only getting 30psi consistently..
 

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Discussion Starter #12
would that cause it to not want to start though thats what has me confused. cause even pulling the decomp lever out and getting good compression it still did not want to run
 

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It it is sticking and releasing the compression needed to make it fire it surely won't run. Fix that first and then see where you are at. They have a hard time starting at full compression so that may explain that too.
 

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Discussion Starter #14
ok so i got the decompression lever and exhaust rocker arm replaced. still no go on starting. the compression came up to 60 psi though. first try on starting it after replacing the rocker arm and lever i got one very loud backfire through the exahust then nothing else. any ideas?
 

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Discussion Starter #16
spark is good will jump a about 1/2 gap. has new fuel. there is no adjustment on the timing other than the cam slot lined up with the crank and that is dead on stright line with the crank. i am at total loss on this one.
 

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have you tried taking the air box off and spraying some starting fluid right into the carb? That will tell you if its a fuel problem. Is it a new plug?
 

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Discussion Starter #18
yes new plug no i havnt sprayed starting fluid in it yet been trying to avoid that i do not like using starting fluid. but here is another thing unless i did it wrong i finally found my timing gun hooked it up. marked the T and the advanced lines on the magneto with a white paint pen cranked it over niether white mark showed up with the timing gun?
 
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