can jetting cause smoke?

[ny300exrider]

i need to know basically straight up, if there is any way that being jetted wrong could cause small puffs of smoke every once and awhile on hard acceleration. this is for my dads 400ex and before i start thinking about a rebuild, i want to make sure jettting isnt even a possibility. basically im asking if the main jet,pilot,and air screw in any form,could cause small amounts of whitish/blueish smoke. if jetting is out of the picture, is there any other possible reasons OTHER than a motor rebuild that could be doing this. the smoke is very random and it isnt on every rev, just after a 5-10second 5th gear run, it will sometimes puff alittle out and sometimes under heavy loads or big hills.

[zephead400ex]

Possibly a head gasket going bad. Or you could be running lean. What does the plug look like? If it a very light color you are too lean, go up on the main jet. If it is black, your too rich (I highly doubt this is the case).

But then again, I could be off base here too.

[ny300exrider]

its possible im lean, ill do a plug check and that can tell me if im offjetted

[400exrider707]

the lean jetting could have caused it to overheat and screw up your rings, thus you would see the blueish/white smoke. Its not directly related to jetting but could be. Ususally black smoke is the only smoke you will see from jetting which is rich. My guess is it needs a rebuild, but theres only one way to find out, dive in to the motor.

[cals400ex]

the 400ex's tend to use a little oil when ran hard. most of the time the problem goes away when you switch to a thicker oil.

[ny300exrider]

hmm i may try a different oil, i dont think im that lean though because i was rich and only went down a size or two from that so i should be ok on. we definitly havnt noticed a power loss, it runs awsome and havnt seen any noticable oil loss. what viscosity oil should i try out cals? i run 10/40 now. thanks for the help

[cals400ex]

most prefer a good full synthetic 15-50 or 20-50 without friction modifiers. i always run the mobil 1 15-50 tri synthetic. now they re-did their oil and i believe they have friction modifiers in them. i can still get the old stuff here locally so the brand is up to you. i am going to start running maxima probably. if you don't want to pay that much, run a non synthetic

[ny300exrider]

ok that sounds good, thanks alot for the help cals

[chucked]

If you are running VERY rich, the gas will wash the cylinder walls and create a suction from the bottom end, thus sucking up oil. When I put a quiet core in my bike, it ran so rich that it spewed out oil!