I bought an 04 Foreman 450 s 4x4 used from an auction. It seems a little beat up (body in good shape but they drove it hard!). Under carriage is all scraped, dented and banged up. Anyways, the engine runs rough and it appears to burn oil or it smokes when i give it gas-smoke is mainly clearish white. The engine also knocks. So my question is what might this be as i am not a mechanic, what should i look for if anything, what parts does it sound like i need to fix it, approx. how much to fix? Thanks for any input on the situation!

 

The first thing i would do is get a service repair manual, then give it a good serving,oil and oil filter change; then clean aiir filter spark plug and check the valve clearance ! If the valves are not within spec's that would cause rough engine and smoke, the carburator could have bad gas,dirt or water in gas tank ! Start with draing the gas tank into a clear glass or plastic container, and there is a screw near the bottom of the carburator to drain the fuel from ! If you see water or dirt or the color of the fuel look's dark are has a bad smell you'll need to remove the carb and take it apart for a good cleaning ; that where the manual comes in handy ! After you clean out the tank and carburator add seafoam to your gas it's a fuel cleaner/stabilizer, you can get the seafoam from O'Reallys,auto zone or advance auto parts for about $5.00 this is better than other gas treatment it will keep the carb, fuel and combustion chamber clear and clean !! The valve clearance is very important to keep the engine running clean, i hope this help's...............williebee

 

piston and re bore thats it , the knocking you here is probably piston slap worn rings and bore will cause smoking,, ring end gaps way beyond specs 150-200 bucks

 

Have looked at the oil? To me it sounds like it has water in the oil from being submerged. If the oil looks milky, then it will take around 10 oil changes to get all the water out. Also check (drain) the float bowl on the carb. There is a drain on the bottom. It could also have water in it .