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Used 2012 300xc jetting help

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I picked up a used 2012 300xc with maybe 80-100 hrs on it. When I friend it before buying it ran fine and was cold before I started it. It was maybe 65-70 outside.

Fast forward to today which is the first time I have ridden it since then(it was a long winter in Maine). I took it out and other than a little bog down low it would run well. After a 30 min ride it had almost no power down low and would have to slip the crap out of the clutch just to stay moving. All the carb setting are as it was before the 30min. It basically only had power if you were close to or on the "pipe".

Temp outside was 50f. The only mods to the bike are a knarly pipe(came on the bike). Because it runs well up top it makes me think the main jet is good but how could it go to hell so quickly?

Anyone care to share the stock carb setting and jetting I should be running with a knarly? Or care to chime in on what could have caused it to go to hell. The carb is clean, fuel is good. Plug looks good, etc. idk why it won't run worth a dam.

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Jetting doesn't change with time.  Dump the old gas out of the tank (probably has water in it).  Drain the carb and spray carb cleaner through the pilot and main jets and get some fresh premix gas, ideally use some non-ethanol fuel.  This is a good inexpensive starting point in figuring out the problem

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I picked up a used 2012 300xc with maybe 80-100 hrs on it. When I friend it before buying it ran fine and was cold before I started it. It was maybe 65-70 outside.

Fast forward to today which is the first time I have ridden it since then(it was a long winter in Maine). I took it out and other than a little bog down low it would run well. After a 30 min ride it had almost no power down low and would have to slip the crap out of the clutch just to stay moving. All the carb setting are as it was before the 30min. It basically only had power if you were close to or on the "pipe".

Temp outside was 50f. The only mods to the bike are a knarly pipe(came on the bike). Because it runs well up top it makes me think the main jet is good but how could it go to hell so quickly?

Anyone care to share the stock carb setting and jetting I should be running with a knarly? Or care to chime in on what could have caused it to go to hell. The carb is clean, fuel is good. Plug looks good, etc. idk why it won't run worth a dam.

Here ya go.

2012 300xc jetting chart

12KTM300XCJettingChart_zps508889b4.jpg

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I'd be surprised if it was anything more than bad fuel from sitting over the winter. Just change the plug, clean out the carb real well and start with fresh gas. Make sure your air filter is clean also.

 

If it was running good before, don't mess with the jetting. At least not until you do the above.

 

Regarding the jetting info in the above post, it is straight from KTM but I wouldn't go by that. I just bought a 2013 300 xc and it ran like crap. Loading up a lot. I had to change the needle and mess with the AS quite a bit. Still don't have it right but it isn't broken in completely. Factory KTM settings seem rich across the board. Once I get it broken in and can go WOT I bet I'll have to put the smaller main jet in it.

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Yep it's probably just water and maybe a clogged pilot. As for jetting I run 38 pilot 168 main and a nedj needle from a 2007 rm250. It works flawlessly from sea level to 4000 feet without touching the air screw.

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Still can't figure out what's causing the problems. New pilot and plug with fresh fuel. Cleaned the carb. I have attached a vid of me trying to take off with it. Basically it has no power untill the middle 1/2 to 2/3 of the rpm range. Idk ifs it's a trashed reed valve, something stuck with the power valve or what. It basically makes like 3hp down low so in order to take off you need to slip the clutch like crazy. Like riding a cr85. Then once it get up high in the rev range it feels normal.

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ImageUploadedByThumper Talk1398635143.167202.jpg

Well the I started tearing it apart on the intake side and the reed valves looked good. Then I pulled the pipe and took a peek up the exhaust port. Looks like the pistion is missing a big chunk off the exhaust side of the skirt. A am worried about where all that metal might be now? As I have maybe ten mins of trying to ride it when it was down on power

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It's all about guilt. I don't know why anyone with half a brain would accept such garbage into their lives.

Dang it man Edited by E-TECH

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