Hi guys I need some help. I have a 99 sp500 with 600 miles on it. Since it was new I had it back to the dealer several times for lack of top end. Machine seems to fall on its face at 43mph and maxes out at around 48 mph.Dealer has replaced pvt and belt. Decided to check the jetting so I put in a new plug and did a flat out run, pulled plug and it was bright white on porcelin and ground electrode. So I yanked the carb and did an inspection found no problems. Out of frustration I pulled the main jet which was a 155cc andmatached it to a drill bit and went up 2 sizes reinstalled carb. Did another flat out run pulled plug again still white???? Went up 2 more sizes and again still white. Thinking it was fuel starvation checked the float level and was fine. Chaecked the fuel pump diaphram and its fine. Also checked valve lash. Still lean and still dies at 45mph otherwise runs the same as before. Put it in low range and goes 31mph. Am I doing something wrong besides killing the 155 jet?????

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