I just changed out the starter on my 1986 bayou 300 2x4, and had to removed the cover on the left side of the engine to line up the starter shaft with the gear on the chain.
after this was done though I know can only run the machine with choke full on. cleaned carb well and no real difference.
didn't know if removing this cover and changing starter would change timing and effect how it runs with choke off... basically just dies when choke is turned off.

 

Wonder if there is an air leak in the air intake system and now machine is running too lean and you have to make it run rich by turning on the choke...