Thanks for the suggestions, I did have the carb slides out to check them but wasn't sure what to look for so I might have missed something there. They seemed to travel smoothly and return to rest at the same rate when manually pushed open. I will have a look at these first since it is a bit easier than the timing.
As for the timing, that was a thought I had, this is a friends sled they bought used about 4 years ago so no idea if the update was done. I tried to see if there was a colored dot on the tensioner but wasn't able to see anything definitive. It has about 15,000 km on it, would the original tensioner have lasted that long? I will follow the timing chain how to and check the timing marks.