Dear fellow forum members: Thank you for such a great, informative site. Your input is invaluable. I have a question here that has stumped 2 local dealers:
I have a 2000 king quad that ran like a scolded horse for 1500 miles. However, it started blowing white smoke after 15 minutes of use and would die. If I let it sit for an hour, it will run perfect for another 15 minutes. I have noticed that it will blow smoke if I take it high speed around a corner or up a steep hill then die.
Here is the kicker: I had the carb rebuilt and the top end rebuilt. After over $1,000.00 it acts the same; running great for 15 minutes then dieing. Any suggestions will be greatly appreciated. Life just isn't the same without the beast.

Thank you,
DOCRYDER

 

Any ideas??

 

White smoke is water, we know that. If it was blue, it'd be oil, but it's not. After 15 minutes, you've reached max operating temp in most situations, that means that after 15 minutes, the heat of the engine running has changed something. Heat causes metals to expand. If there is a crack in the water jacket on the jug, you will have water leakage into the combustion chamber or the crankcase. Is there water in the oil? No? Tear down your engine, have the head inspected and the jug inspected for any cracks. There is a process called magnafluxing. There are a couple other methods, but I think this is the most common.
Crack in the jug/head. That's my guess.

 

Oh yeah, is the KQ 300 water cooled?? And did they MAKE a KQ300 in 2000? I thought it was a 500 then.

Or was that the Quadmaster?

???

 

Oops, magnafluxing only works on cast iron. I guess it's pressure testing or dye.

 

Drain your gas tank.

The old King is air cooled. No coolant to burn off.
The tank has a two step outlet and the main tank draws gas from a raised stalk inside the tank while 'reserve' draws from the bottom. I'll bet there is water in your gas. The gas will ride on top of the water so you get straight gas until you start riding it and sloshing it all around and then the water gets mixed in and drawn into the motor, steaming up the exhaust.
When you let the bike sit for a while the water settles back down to the bottom and it will run clean again.

Drain and clean that tank from the bottom valve outlet and fill with clean gas and I bet your problem goes away. And replace that hose on the gas tank that pokes down intio the steering head. [img]i/expressions/face-icon-small-smile.gif[/img]
Every tankful, put a spoonful of methyl hydrate in the gas and it will emulsify and get rid of any residual water that accumulates in the tank from condensation.
Keeping the tank near full helps reduce condensation.

 

I would try A NEW sparkplug an change the gas like glen livet said.The newer oxygenated gasolines are hydroscopic an attract water like brake fliud.The next things I would think would be either improper break in,not suppose to scream a new engine,due to cross hatch on cylinder glazing over,then ring an piston will never break in it will lead to poor oil control due to no ring or poor ring seal..it almost sounds like a bad coil/cdi unit bike gets up to operating temperature or hot an ignition is affected an quits,that is telltale sign coil or electrical system is to blame then it cools down an does same thing.Electrics usually dont like heat or too much of it at least.White smoke is usually coolant or condensation but since king quad is air cooled maybe there is crack in cases lettting in moisture or water somewhere.Good luck an keep us updated on what you find or how you make out.