pre-mix oil in air boot?(and other thoughts)

[r.2 stroke]

Hi all,
Just to put my mind at ease,i seem to remember a thread i read a couple of years ago,that it was ok/common to find a little oil sitting in the bottom of the air boot.Every time i pull out the carb and clean out the inside of the air boot itself,i would soak up about a couple of tea-spoons worth of oil with a rag,the oil looks exactly like Motul 800,which is what i use for the pe-mix.
The bike does run a little rich maybe('04 200,stock pipe,airbox lid drilled out,stock main jet,pilot #45,stock needle in second from top position,pre-mix 40:1,riding elevation pretty much sea level)
I am going to get a #58 main jet,and a #42 pilot and try that shortly.Most of the riding i do is in deep sand, or tight sand based woods areas at sea level,and i don't mind running a bit rich and erring on the side of caution,but any advice anyone has to offer is most welcome concerning the oil in the airboot,or any jetting thoughts.Does anybody run an in-line fuel filter?
Cheers,
Rog.

 

[oldguy]

I doubt it is Premix you are finding. It most likely is Filter oil that dripped off the air filter inside the boot.
That is unless you are referring to the collar between the carb and the reeds as the boot.

 

[ridejunky]

I'd be more concerned if it wasn't there, although a couple of tea spoons does seem excessive.

 

[r.2 stroke]

I doubt it is Premix you are finding. It most likely is Filter oil that dripped off the air filter inside the boot.
That is unless you are referring to the collar between the carb and the reeds as the boot.

Hi,i'm resonably sure it's Premix,as its red coloured oil in the boot im finding(between carb and air filter box),just like the Motul 800 2t im using,and my air filter oil is a bright blue colour and quite tacky.....hmmmn.

 

[oldguy]

Sounds unusual for it to be pre mix at that point as fuel/oil is not introduced before the carb into that path. It would have to be blowback of some sort for premix to reverse direction out of the carb.
The color differance is strange tho
I'll back out gracefully and let someone more familiar with the KDX chime in

 

[joebiodiesel]

Anyone ever ride one of the old snowmobiles with the air horn sticking out towards your stomach? If you did, then you remember getting home with premix all over the front of you. Those old piston port engines sprayed nearly as much fuel backwards as they did frontwards. I'm sure an engine with reeds doesn't do that nearly as much, but I don't think finding premix in the air cleaner would scare me. Not as long as it was running well.
That said, there are a bunch of guys on this forum that are familiar with every square inch on their bikes that can tell you whether they've seen that or not.
Joe

 

[BigRedAF]

If you put your hand near the back of a two stroke carb and rev the engine when it's on the way back down to idle it will spit back a mist of fuel and oil. The fuel will evaporate and leave a light oil film. The engine is making high vacuum when you close the throttle at high RPM and the slide is shut. For what ever reason it does spit back a mist. Sounds like yours is a bit rich. I run Amsoil, it's red and my filter oil is blue. I too have a light film of red oil in my boot.

 

[ridejunky]

Anyone ever ride one of the old snowmobiles with the air horn sticking out towards your stomach? If you did, then you remember getting home with premix all over the front of you. Those old piston port engines sprayed nearly as much fuel backwards as they did frontwards. I'm sure an engine with reeds doesn't do that nearly as much, but I don't think finding premix in the air cleaner would scare me. Not as long as it was running well.
That said, there are a bunch of guys on this forum that are familiar with every square inch on their bikes that can tell you whether they've seen that or not.
Joe

Wow thats a hillarious but perfect example, sometimes you forget how bad those old sleds were, helmets too.

 

[AwfulSmokey]

Hi all,
Just to put my mind at ease,i seem to remember a thread i read a couple of years ago,that it was ok/common to find a little oil sitting in the bottom of the air boot.Every time i pull out the carb and clean out the inside of the air boot itself,i would soak up about a couple of tea-spoons worth of oil with a rag,the oil looks exactly like Motul 800,which is what i use for the pe-mix.
The bike does run a little rich maybe('04 200,stock pipe,airbox lid drilled out,stock main jet,pilot #45,stock needle in second from top position,pre-mix 40:1,riding elevation pretty much sea level)
I am going to get a #58 main jet,and a #42 pilot and try that shortly.Most of the riding i do is in deep sand, or tight sand based woods areas at sea level,and i don't mind running a bit rich and erring on the side of caution,but any advice anyone has to offer is most welcome concerning the oil in the airboot,or any jetting thoughts.Does anybody run an in-line fuel filter?
Cheers,
Rog.

I have an 89 KDX200 and i just got done jetting my carb with lots of help from peeps. I'm not sure the differences between the years but anyhow. My bike used to have oil like you say. My bike was running way rich.Since jetting the oil has gone away and my bike smokes almost none now. the 45 pilot sounds a little off, i would try a 42, but the main sounds way rich. I have a 152 in mine and it's working extremely well with a CGK needle 2nd clip from top. My bike is pretty much stock except for power reeds and lid removed. I went from running a 158 main and a 48 pilot to a 152 main and 42 pilot. I might possibly have to lean a little further but i'm going to live with it and wait for the temp to build back up( yes folks it can get cool in Florida brrrrrr )

 

[steve.emma]

mate all 2stroke bikes seem to do that to an extent. the amount of oil you see will depend on the design of the air boot and how the bike is ridden etc..
the reason for the oil i believe is to do with the intake air being pulsed into the carb as the reeds open then shut. when the incoming column of air hits the closed reeds it then bounces back out of the carb into the airboot causing a mist of fuel. the fuel evaporates but of course the premix is left behind until its cleaned off. very normal stuff, dont worry about it. :cool:

 

[D_Moen]

Yup it't normal for some fuel to be aspirated out of the carb, usually at lower throttle settings (which KDXs seem to seel a lot of!) I fly RC airplanes, and on my favorite, the engine is not in a cowling, it sprays fuel/oil on the airplane when in flight. :(

 

[AwfulSmokey]

Yup it't normal for some fuel to be aspirated out of the carb, usually at lower throttle settings (which KDXs seem to seel a lot of!) I fly RC airplanes, and on my favorite, the engine is not in a cowling, it sprays fuel/oil on the airplane when in flight. :(

Thanks, that's good to know.