whiff of smoke when backing off the throttle?

when i back off the throttle in my baja (when operating the throttle lever on the carby) you get a short whiff of smoke, it doesnt blow smoke when u put ur foot down but if u back off quickly u can see a bit. is this just unburnt fuel? shouldnt it smoke when u accellerate not the other way around?

rich mixture?

tappets maybe? (though i did them recently)

Nicko

Worn valve guides or valve stem seals (not sure what's in a vw).
Closing the throttle at speed creates vacuum in inlet manifold and sucks oil down past the valve stems.

[ Edited on 10-5-07 by lexm ]

not a worrie when you back of and valves and things go out well could be a prob but now will run forever if your really worried using one of the oil additives that add a coating for wear would be ok

lexm wrote:Worn valve guides or valve stem seals (not sure what's in a vw).
Closing the throttle at speed creates vacuum in inlet manifold and sucks oil down past the valve stems.

[ Edited on 10-5-07 by lexm ]

yeah, that's it. But no seals required in a VW as the valves are installed facing 'downhill'

hmm, ok, not a huge issue atm?