Kxf250 blowing white smoke

[2fitty]

My mate just bought an 08 kxf250 and it's blowing quite abit of white smoke could this be a blown head gasket? Is that a expensive excercise to repair, bike runs and starts well.

[FJRider]

White smoke is from water ... the trick is to know FROM where ....

Either there is water in the fuel tank ... or the water is from "Somewhere else" ...

Water going into the cylinder may cause a hydro lock. A sudden stop is then expected.

Drain the fuel tank (and fuel system ... cabs included) ... collect it and check for water. Replenish with fresh fuel and try. (Cheap option)

The head gasket is the next option. If the head is warped (or cracked) ... simply replacing the head gasket wont fix the problem.

[barty5]

check the radiator level if it low good chance it will be head gasket haven't seen a mx 4t with warped head in all the ones ive done yet.
coolant burning in the motor normally smells some what sweet.
other wise it could be burning oil.
either way can be expensive if you cant do it your self.
water in carb / fuel tank of any reasonable amount would make it hard to start other option is check the plug as long as its not new having coolant/ water going through motor can cause the plug to be washed clean if its using that much though the radiator should have been needing a top on a regular basis.

[2fitty]

Cheers guys, didn't have a lot of coolant in it and it was pretty brown and thick which to my limited knowledge means it's proberbly been overheated at some stage, flushed radiator and filled up with new coolant manual says 1.1l but wouldn't event take a litre and once started and warmed up was spittitng coolant from the overflow, drained all fuel cleaned out carb smoke has eased up but not gone completely and only smokes on accel.
Bike has done 130hrs and about 5 on new top end supposedly.
Gutted for my mate as it's his first bike and hasn't even ridden it yet, hope it don't put him off riding.


check the radiator level if it low good chance it will be head gasket haven't seen a mx 4t with warped head in all the ones ive done yet.
coolant burning in the motor normally smells some what sweet.
other wise it could be burning oil.
either way can be expensive if you cant do it your self.
water in carb / fuel tank of any reasonable amount would make it hard to start other option is check the plug as long as its not new having coolant/ water going through motor can cause the plug to be washed clean if its using that much though the radiator should have been needing a top on a regular basis.

[barty5]

run it for a bit if it keeps spitting it out rad cap try replacement cap ie swap with yours if pos if yours starts spitting coolant replace cap.
If it stops spitting coolant but level keeps dropping the it will need a head gasket check oil as well make sure its not all milky could be sign of bad water pump seal.

[2fitty]

Confirmed blown head gasket and water pump seal, good to go now, cheers for the input guys


run it for a bit if it keeps spitting it out rad cap try replacement cap ie swap with yours if pos if yours starts spitting coolant replace cap.
If it stops spitting coolant but level keeps dropping the it will need a head gasket check oil as well make sure its not all milky could be sign of bad water pump seal.

[2fitty]

Well that was short lived, gasket blew pretty much straight away, sent head and cylinder to nz cylinders and have confirmed a warped head bout a 2thou gap on exhaust side, so looking for a secondhand head now, if anyone has one lying around in their shed taking up space will happily take it of your hands!

[Ocean1]

Well that was short lived, gasket blew pretty much straight away, sent head and cylinder to nz cylinders and have confirmed a warped head bout a 2thou gap on exhaust side, so looking for a secondhand head now, if anyone has one lying around in their shed taking up space will happily take it of your hands!

What's so special about the head that it can't be machined flat?

[2fitty]

Alloy has gone soft and they can't guarantee it will hold up once it hits running temp again

What's so special about the head that it can't be machined flat?

[barty5]

Go and talk to Jared at GK Engine re conditioners 43 Jellicoe Road, Panmure, Auckland 1072 (09) 570 5336 when i owned Newmarket auto repairs he use to do all our work and all bike heads and cylinders etc is very help full and dose a good price may be able to retreat the head for you or at least give you a 2nd opinion. Ive rebuilt a heap of bikes with blown head gaskets etc never had one that failed that bad.
otherwise try ebay if you cant get it shipped to NZ can get it sent to me in Connecticut ill forward it for yah.
Also some good wreckers in aussie but they are normally expensive for parts there.

[motor_mayhem]

Alloy has gone soft and they can't guarantee it will hold up once it hits running temp again

Brand new at BTOSports for $270US - sounds like a pretty reasonable deal

http://www.btosports.com/p/moose-racing-replacement-cylinders

[barty5]

Brand new at BTOSports for $270US - sounds like a pretty reasonable deal

http://www.btosports.com/p/moose-racing-replacement-cylinders

except thats the cylinder not the head :Oops: