Last couple times out sled felt like it was loading up on bottom end. Once it hit 6000 it ran fine. Pulled rpm and hills fine. Then couple hours into ride yesterday rpm started falling off. Then roped out at 7000. Pretty sure exhaust valves where not opening. I have a can on it. Not exhaust note change at 6000. Pulled off servo checked cable operation. Seems to open and close. I have to push last 1/4 inch of valve return to achieve fully closed exhaust valve. Do not know of this is normal. Put sled back together. Seems to run 90% better. Just not quiet right. Sled has 1000 miles on it. No check engine light. Anyone have any idea. What maybe going on. Or how to adjust valves.