rebuild question

[powercrazy3]

i just fired up my 06 kx250f from a fresh rebuild. it had been sitting for a couple months though. i fired it up and it was fine, then it was spitting some fluid ( looked like coolant in the oil) from the overflow tube that comes out of the right side of the motor. i shut it off immediately. i looked in the site glass and like i said it looked like it had coolant in the oil. tomorrow im going to change it and see what happens.....but my question is that is there a seal that could be bad?

thanks fellas

[SHLEPY]

water pump seal.

[sandblaster]

+1

[Motorrad]

[don46]

the oil looks frothy after running, but doesn't have water in it, not saying it doesn't just that the oil gets aerated looks funny. Sometime after rebuild they will spew oil out the overflow, I think the reason this happens is the rings aren't seated yet and you get blow by, the blowby adds pressure to the crankcase and cause oil to leak out the vent. after you run it it should quit. I had this happen several times after a new piston and rings, run it for a bit and you'll be golden.

[powercrazy3]

[powercrazy3]

It was also leaking from the valve cover gasket. Not a lot but some. About the same color also

[don46]

was the picture right after running or had it been sitting? I don't like the looks of your oil but it doesn't really look like water either. and as I said a new set of rings may not have seated and cause alot of crankcase pressure. oddly I never had issues with the 450 only the 250f

[powercrazy3]

That was after a minute or so of running.

[don46]

Top off your fluids, take it out and ride it pretty hard to get the rings to seat, I think that will be the end of your problems. I had one 250f that took 3 rides before it quit blowing oil out the vent. We not talking major blowby on the rings but enough to build pressure in the crankcases and I think enough to areate the oil

[powercrazy3]

I'm gunna change the oil and see if it does it again. Hopefully it's just being temperamental. I'm ready to ride!

[powercrazy3]

I started it today after work and it didn't leak at all. So I'm hoping all said is done now
What is a good setting for the fuel/air screw? 1 1/4 turn out?

[SHLEPY]

That's a good start depends on were you are altitude wise,1 to 1.5 in that range just check throttle response.

[don46]

On that bike it is a fuel screw not an air screw like most 2 strokes, it will rpobably be 2-2.5 turns out. What I usually do is raise the idle to about 2000-2500 turn the screw in till it starts to run erratic, then back it out, it will pick up rpm as it goes out until it starts running rough turn it in about 1/4-1/2 a turn and you should be good. Turn the idle down to where you want it, and then blip the throttle a few time to make sure you have no flat spots.

I am assuming you have an after market fuel screw, if not get one, its the only way to tune the carb. The other thing I always did to my 250f was to wire the accelerator pump, so when you give it throttle it shoots gas, stock they are sproing loaded and gradually shoot fuel.