I have been having a smoking problem with machine .Smokes when load is put on machine( going up hills).I think smells like anti-freeze,other folks seem to think rich condition.So what I did to troubleshoot this was pressure test cooling system and pressure test ok,Rebuild carbruator,check muffler for plugged condition,check oil pump adjustment and choke adjustment as per manual,bled cooling system,compression test ok,plug seems to be burning a bit on rich side but not gas/oil soaked.I decided to just pull engine to replace water pump seals,,new rings,,Reinstalled engine and same problem,,purchased oil pump by-pass kit ,premix oil/gas 40:1 and no difference.I have to be missing something,,I don’t know if there is an unusaul ongoing problem with this model atv,Maybe someone can help and give ideas.I am thing maybe some kind of substance stuck in muffler causing the smoke,but imagine it would be burned off by now.Another idea is if a 4 cycle engine would bolt up.I would really appreciate any ideas.