Have a 1986 honda 350 fourtrax runs and idles like a dream.. After about a minuet of running it will produce white greyish smoke and spit oil out of exhaust pipe with no loss of power. What could cause this ?Thank you for any help.

SOURCE: 1993 TOYOTA TERCEL 1500cc Valve Seals Replaced now smokes much worse

You either have had the wrong valve seals installed, they are physically missing, or the valves are incorrect (too loose in the guides/stem too thin). The rocker arm seals will not contribute to your issue. If it did not have the oil smoke before you took the head off, the issue is with whatever the machine shop did. Valve seals have to fit TIGHT, or oil will go down the valve stem into the intake.
Take the head back to the machine shop & tell them to fix it. For free.

Anand Kumar

• 2035 Answers
• Posted on Oct 19, 2008

SOURCE: White smoke exhaust

White smoke is caused by coolant or water coming out the tail pipe. There is a chance that the white smoke was caused by water splashing up from a puddle onto the exhaust pipe. Keep an eye on the coolant level in the radiator in any event. If its less then there leak coolant leak in the car engine which is causing this problem....

SOURCE: White Smoke From Tail Pipe/Exhaust

It often means that you are burning antifreeze. You asked if it needs antifreeze, have you noticed any leaking out of the reservoir tank while you are running it? Sometimes when the head gasket goes it will produce a passage for the antifreeze to pass from the capillaries into the combustion chamber. It is easy to check if you have an air compressor. Remove one of the rear sparkplugs and the radiator cap. Fill the radiator and then push some air into the sparkplug hole (get a good seal in case a valve is open). Repeat with all the cylinders and watch for air bubbles coming up into the radiator. If bubbles come up or fluid is pumped out, the head gasket is blown and must be replaced. It is more likely to happen at the back of the engine because it is farthest away from the fan and therefore gets less cooling. Also check your oil for discoloration. If it is a brownish color it could mean your oil and antifreeze are mixing and has the potential to damage your bearings

SOURCE: thick white smoke coming from exhaust

I would think this will be a blown turbo.

These are fed by a small oil pipe and if the unit overheats (due to wear) - this oil fill feed directly into either the inlet manifold - or the outlet - exhaust.
If it is spilling oil into the hot exhaust - you will get a thick white fog. You can confirm this by placing a clear glass bottle or jar in the exhaust stream - and see if it gets a thick coating of oil on it. If it evaporates - it's water, if not - or feels oily - new turbo or overhaul.

Best get is sortd sooner rather than later - as you may be able to save most of it for an overhaul rather than scrap it if badly worn.