I have a 02 foreman 450es .When I first start it up it does not make a lifter tapping noise, once vehicle runs and is in a hot mode, after a start up of engine I hear upper cylinder noise that sounds like a lifter not getting lubrication for a few seconds. Valve adjustments have been performed and the noise is still there on a hot start up of engine. If vehicle sets for 10 minutes or longer after shut off the lifter noise does not show up.
Is this normal or do you have some advice on what I should be looking for. thx.[img]i/expressions/face-icon-small-confused.gif[/img]

 

It sounds like you could have a possible oil pressure problem or for some reason the oil is getting thined out. When the engine gets hot the oil will thin out vs. being thick when the engine is cold. With the thin oil you could have a lifter bleeding down (assuming its a hydralic lifter) and when you let the engine shut off and sit the oil has time to thicken up.

Or you might have a oil pressure problem. Again the pressure will be higher when the engine is cold and it will naturally drop some when the engine is hot. It is now a matter of how much the oil pressure is dropping. I would call your local Honda dealer and see if there is a port some where on the engine to hook up a oil pressure gauge to take a reading

 

thank you for your reply.

 

My fourtrax has done the same thing for about 3 or 4 years now. I figure if it was anything too severe, it would have shown itself by now.
It has very gradually grown louder, until I tightened the valves, then went back to just the slight tapping when first started up when hot. I think it is the valves, and the heat makes them just a little looser than when hot (the aluminum head swells more due to the heat than the steel valves stretch).