Oil boiling?

[ajax]

89 XT600 Kicker

Question; 2x in last month motor (rocker box) sounded like oil was boiling after bike was shut off. Ride was not really that stressful nor long. Was driving 2 up (90lb kid) on a fire road mostly 2nd gear. Drove fine whole way, cooled it and drove back with no problems. Changed oil. Few weeks later same results after similar ride.
Seems to be fine but very curious as to this. Oil level checked fine. Has anybody else experienced this? I'll check the temp with a digital thermometer next ride to get a base.

Thanks
Greg

[juanvaldez650]

Are you sure it wasn't fuel?

[Jens Eskildsen]

Yeah, its more likely the fuel boiling.

Go faster

[javkap]

Fuel boiling where???

I have serious doubts that you can note the oil boiling in the sump on the bottom of the engine or in the reservoir and engine oil start to boil from 140ºC and up regarding type and viscosity…

For me sound like the suction of the carburetor inside the air filter box or even oil there from vent being suctioned…. Just open the box and check.

[ajax]

Its a sizzling sound. I have read before that it is probably fuel but it sounds like its coming from the rocker head.
I looked in fuel tank and all looked normal at the time of noise.
Oil that came out looked and smelled fine.
Thanks
Greg

[javkap]

Fuel can’t boil in the tank, okay maybe with fire under but you or your treasures will recognise it before to hear it boiling...
Maybe vent in the tank is clogged and you hear the air trying to go in or the fuel as opposite.
Or if sound comes from the rocker head could be the vent hose disconnected, fractured or there is a crack in the head itself…

[steveloomis]

What about the possibility of fuel boiling the the float bowl? I've seen aftermarket aluminum plates that bolt on the carb to shield the carb bowl from engine heat. It was said that it helped with hot starting, might be after a long hot ride the bowl could be very hot.

[Jens Eskildsen]

Originally Posted by javkap

Fuel boiling where???

I have serious doubts that you can note the oil boiling in the sump on the bottom of the engine or in the reservoir and engine oil start to boil from 140ºC and up regarding type and viscosity…

Engine oil doesnt boil anywhere near 140C, you need to atleast double that figure.

[2499]

On my xt600z 3aj the fuel boils in hose from the right fuel valve. The hose is just over the exhaust, and the bobbles can clearly be herd when the pass through the tank.

I cured by it wrapping the fuel line with alu-foil.