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Smokey 450

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My 04 450 SX is starting to emit a blue smoke from the exhaust. Under heavy load it will put out a small blue haze but under deceleration it will put out a large puff. At idle it wont smoke, and you can rev it up and it wont smoke but as soon as you let off the throttle it will emit a little blue puff of smoke. I rode at my local MX track at dusk the other day so smoke will look bad at this time of day, but a few people said "man whys your bike smokey"? I really dont know where to look first but i believe that valve stem seals could be the problem if the smokes worse on decel......? someone help?

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oh and i believe it may be a head problem because the head is the onley componant that hasnt had any work as yet

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Same thing happened to mine. It would blow a little out when you blipped the throttle and then puff when you let off. Also burned a lot of oil, not really visible smoke, but the oil moved down the glass where I could notice it. Took the head off and the intake guides were almost ovaled. The titanium valves in the SX wear the guides out quick. Of course you may want to call a dealer or KTM specialist and describe your symptoms because I'm not an expert, but it sounds similar to the things I saw.

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Guide wear seams to be an issue with all? of the Ti valve applications. I just re did the head on a KTM 450 motard with one season, and the guides where worn .025" oversized! (.003" would be ugly)

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You should be able to tell if it's the guides when you remove the head and valve springs. Pull the valve down an inch and wiggle it. If it has significant play it's shot. If the valve feels tight and doesn't move then it may just be the seals or an unrelated problem.

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I am not a specialist, but I know two things: if the smoke is blue - the problem is with piston rings (the oil is going from engine to the spark plug), if the smoke is black - you need to set up mixture control screw in carburetor. If you drive more than 100 hours on your bike, it is better to change the piston with rings. Check the colour of the smoke!

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its blue. i took off the header pipe and there is oil down the stem of my valve so it definetly is stem seals and/or guides. Now to do this job i need a chain breaker to break my cam chain dont i?? And do i have to buy a new chain or just a new link???

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Yes, you need the chain breaker. You can buy a link and rivet it back together with the same tool.

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cool. heads off as i broke my friend from a Kawasaki shops chain breaker i just ground it down and am getting a new link ($11 AUS). hope it all goes ok!

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