I bought it 2 years ago, but rarely used it. I was with a friend out riding on the streets one storm. I let him drive and since I wasnt letting him go out alone with my sled, I hopped on the back. About 2 miles from home it started knocking. I couldnt hear it too well and with his lack of engine diagnosis and noise awareness, he was convinced it was an exhaust leak (he knows NOTHING about engines BTW). It wasnt too far from home so I rode it back (not like I had a choice). By the time I got home it was very underpowered and knocking bad. Im not too sure what caused it, but it could have been me tach'in it out the night before, which isnt the thing you are supposed to do on a new engine thats not broken in completely,but I just had to. Burried the speedo past 100

. Or it could have been the previous owner selling it to me with a problem that I was unaware of and thats why he sold it. Could be both, could be somethign else, not sure. I reset the tripomoter when I bought it and as of right now, it says 47 miles. At least Im well trained with a with the use of a wrench.