Kawasaki petrol has taken up smoking!

[Mith]

Kawasaki 12.5HP petrol engine. Air cooled.
It kicks out a load of black and white smoke when starting from cold. Like LOADS of smoke. It runs real rough, you drop the revvs and raise them and its smooth.
Runs sweet otherwise, is powereful, thought not as much as i would expect, so possible loss of power.
Its kinda hard to start and you need to turn it over quite alot

Whats wrong with it?
(its history is of abuse and suchlike, but ive serviced it ect)

thanks for any help

 

[ZJ_HR]

Clodged air filter???

 

[Rch]

A strategy with rough running gas engines that has fixed the problem with minimal fuss and I do before going deeper is the following: start it up with not much fuel in the tank , run it ~1500 -2000 RPM and pour lacquer thinner into the gas tank till it just starts to run ragged and run it for a few minutes. Lacquer thinner is the active ingredient in carbureter cleaners like Gumout. I've had gas motors gain 75 RPMs, smooth right out within a a few minutes from this fuel system cleaning manuever. I then fill the tank with gasoline to dilute the lacquer thinner. This is especially helpful if the engine has set awhile and gas has evaporated.

 

[Ozarker]

Sounds like a flooding issue. Maybe fuel is leaking past the needle and allowing raw fuel to pool in the intake when it is sitting. This would cause way too much fuel to the cylinder on startup and that would account for the massive black smoke and starting difficulty.

 

[Mith]

Ok, cheers, ill try that
The air cleaner is quite clean, maybe ill invest in a new one
Ozarker, would i notice this by beieng able to start from cold with no choke?

Thanks!

 

[Mith]

Well Ozarker wins first prize!
Tried starting it this morning without any choke and el viola no smoke! So i guess it doesnt need the choke.
I did take a look inside the carb (the aircleaner is kinda dirty btw) and there was oil there /forums/images/graemlins/confused.gif
the air filter is very oily and there ws a small amount of oil in the bottom of the carb below the air filter, is this right? /forums/images/graemlins/confused.gif

 

[Rch]

If there is a lot of blowby(piston rings leak compression), oil from crankcase gets pressurized and sucked in to the intake air PCV (positive crankcase vent) valve and dirtys the air cleaner and and deposits in the carbureter. An overfilled crankcase will do the same by whipping up and aerosolizing the oil thus sending alot of oil through the PCV valve into the air intake. The PCV system is designed to burn oil fumes and replaced the old crankcase breathers that discharged said fumes into the air.
The PCV valve prevents a backfire from going into the crankcase and possibly igniting gasoline fumes that that leaked past the rings ( maybe if flooded or the rings are shot) down in the crankcase. That happened to me on an old 1937 Plymouth and the oil filler cap ( friction fit) was lauched is if a bullet . It hit the ceiling /forums/images/graemlins/shocked.gif They are screw in now for a positive no leak closure.

 

[Ozarker]

Maybe just use half choke in this mild weather.

There shouldn't be a lot of oil in there. I am not familier with your specific engine but oil in that area indicates that it is being blown in or is leaking in from someplace. As Rch pointed out, excessive blowby causing excessive oil fumes to enter through the PVC would be the first suspect. It may be time for your mechanic to check it out.

 

[Mith]

Thanks for the replys
Its got good compression so i guess it probably not blowby /forums/images/graemlins/confused.gif maybe ill test it tomorrow
Im thinking it may either be cos the air flter was too oily and its seeped down, or its overfilled, OR, its meant to be like that, you know, to catch any last dirt particles.
It turns out its pressure lube, dont know if that makes a difference, its a strange engine

I am my mechanic /forums/images/graemlins/crazy.gif its what i do, fix lawn tractors, just never come across one thats like this, so i asked before i screwed it up bad

sounds like its either nothing or something hard to fix, if its hard it works so its staying like it is, unless its a REAL easy fix...... It works well so im happy /forums/images/graemlins/laugh.gif, it was cheap, and the gearbox is a pile of

ill drop the oil level to 'add' and clean it out, change the filter for clean un oly and see if the oil comes back

thanks

 

[Rch]

If it runs good and has power, oil is cheap in that size engine as are fiters, Douching the carb with lacquer thinner then running some crankcase/oil cleaner like Alemite CD and a short hard run at tempature may free up some rings' oil channels etc. I'd drain the hot oil and change the filter then and fill with a good grade of synthetic and see what I end up with. /forums/images/graemlins/tongue.gif And clean that PCV valve too