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STX 12F running rough

2354 Views 1 Reply 2 Participants Last post by  mascaro1
I've got an 06 12F with 41 hours that this year has started running rough in the mid range. It feels great at full throttle (runs 54 mph with me at 250 lbs, the same as when new. But if you run it at mid range, it feels like it runs rough. And sometimes after extended midrange (one or two minutes) it doesn't want to rev up to full throttle. We changed plugs yesterday with no effect. Any ideas of what to check next?
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Check cylinder compresion

I have a 2006 STX 1500 that would stutter a little at low rpm then at mid to top range would run fine. Turns out the number 1 cylinder had about 90 psi compresion and should have been over 200 psi according to the mechanic. It turned out to be the valve stem seals leaking. The number 2 cylinder was at 180 psi. I had them replace all of the seal at one time. I only had about 90 hours on the ski and in general it was not run all that hard. I was a little disappointed and concerned with the longivety of the seals considering the cost to have them replaced.
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