400ex Crankcase Venting

[KAWSAM62]

Hello has any one removed the crankcase vent tube on the intake boot on a 400ex it is attached to a white plastic bottle via a hose to the engine, it pulls a vacume on the motor so if you go to a aluminum air box do you end up disconecting it from the air boot and if you do , do you plug the whole in air boot and what do you do with the breather hose ? or do you just leave it alone staying factory let me know please tx :confused:

[DGR Designs]

correct me if i am wrong... but you need that tube and if you go to an aluminum airbox, the airboot still has to attach to the carb from the airbox. the vent tube stays the same if you have an aluminum airbox then wtf does that vent tube have to do with anything? just throw you airbox in and hook up the boot like you normally would with the OEM airbox. duh... am i wrong?

[KAWSAM62]

IT PROBLE STAYS FACTORY BUT IF YOU NOTICE THE PLASTIC BOTTLE HAS OIL RESIDUE IN IT ,IF YOUR QUAD HAS ANY MILES ON IT, LIKE MINE YOU WILL GET OIL BLOW BY CAUSED BY THE VACUM WHICH IS WHY YOU ALWAYS NEED TO ADD OIL TO THE MOTOR IT IS BASICLY BEING SUCKED OUT AND IN TO THE CARB THRU THE MOTOR 400EXS USUALLY DONT LEAK OIL THEY SUCK IT IN THROUGH THAT TUBE SO IF YOU DISCONNECT IT WILL THE OIL CONSUMPTION STOP JUST A THOUGHT;)

[BadA$$440]

you can disconnect it but dont ride with out pugging thehole in the airboot cus dirt can get in there. Just leave it on, its doing its job, i have alot of oil resude in mine to, its normal

[L.Vegas400]

as things heat up they expand. this is how the pressure is released. as the oil heats up and gets slug around the inside of the eng. it creates a mist if you will, that is where the residue in the 'bottle' comes from. vehicle engs have these as well, called a pcv valve.

as i wrote this i thought of another expination for the vaccum. if there was no vent or vaccum, you would build up pressure in the eng., and where would be the easy exit for the pressure, the many seals and gaskets, causing a constant leak that cant be stopped

my $.02

[KAWSAM62]

thats what i really thought but i wanted to see if anyone knew anything different you dont know unless you ask and you never know what you can learn on these forums ive allready gotten lots of good info tx:D

[KAWSAM62]

tx to all again:D

[BadA$$440]

Hey KawSam, i see you live in Jacksonville, florida. Do you go to the FTR races? I live on the SW coast in cape coral ( 2hours below tampa)

[KAWSAM62]

no i have not but im working my way there no preconceived notions just would like to try it once or twice so i am trying to join a local club that some of its membership have done hare srambles or endurose and the such

[kineo3]

Oil in this bottle is normal? How much oil is considered normal? On my 400ex oil flows though this crankcase overflow and into my airbox. It also saturates my airfilter with oil. It sounds like other 400's have this problem, just not to the extent that I do. I have taken it to the shop and they are stumped, as am I. It has great compression and does not smoke. I am considering just putting a cap on the end of the hose, but I am afraid that pressure build up will be released somewhere else. Any one have any thoughts? I have asked before but I am still looking for that elusive answer.

[KAWSAM62]

IS YOUR OIL LEVEL CORRECT TO MUCH OIL IN THE TANK COULD CAUSE EXCESS OIL TO PUSHED IN TO YOUR BOOT AND AIR FILTER OR POSIBLE BAD RINGS ON THE PISTON CREATING EXCESS BLOW BY JUST A THOUGHT:confused:

[kineo3]

The oil level is actually a little low if anything. I too thought it might be bad rings, but the compression is perfect and it does not smoke a bit:confused: :confused: :confused: :grr

[KAWSAM62]

hello does the oil level in the tank go down with the increase of oil in the air box just a thought maybe what your seeing is a overly oiled filter that ozing oil happened to me once when i oiled a filter and didnt wait a day for it to dry a little before install it dripped oil all in the air box scared me to death hope this helps:cool:

[kineo3]

I had that same thought. I went and purchased a new filter and oil was still in the airbox. I can see where it fills the crankcase overflow (plastic bottle) and flows right into the airbox. I have to drain the plug at the bottom of the airbox after about 20 minutes of riding. It runs awesome other than this unfortunate mystery problem. This is why I was considering just blocking of the crankcase breather hose but I am unsure of the potential consiquences. I wish I could just diagnose the problem and fix it. I am reluctant to tear the motor down, replace rings and still have the same problem.

[KAWSAM62]

cant beleive the dealer cant help maybe you should try calling some of the companys that do hiperformance 4 strokes they would surely have had this problem before:confused:

[KAWSAM62]

also i guess you didnt have the extended warranty if so id take it to the dealer and make them fix it also you cant blk off the tube it has to vent or oil will pore out of ever seal on the motor:confused:

[KAWSAM62]

just got a thought on the top of the oil tank there is a vent hose that runs upward on the frame i think its function is to keep the oil tank from pulling a vacum and act as a overflow if there is to much oil in the system maybe its pluged or pinched forcing oil out your breather line the hose is small and attaches with a clamp not the threaded oil return line but right next to it on the top of the oil tank:confused:

[kineo3]

I will take a look at the hose on top of the tank. I beleive it is somthing simple such as that. I do have the extended warranty, but I imagine that only covers certain things on the 3rd full moon after the second sunday if it was raining out.:D thanks for your help. where do you live in Fla.? My parents have a house in titusville I visit in the winter.

[KAWSAM62]

live in jacksonville and i do think your ext warranty will cover that problem my dealer told me when i bought mine that if i drowned it in a lake it would be coverd you need to put presure on them to fix the problem call there boss ,distict manager somebody make them fix raise some @ell good luck:grr

[L.Vegas400]

Originally posted by kineo3
I had that same thought. I went and purchased a new filter and oil was still in the airbox. I can see where it fills the crankcase overflow (plastic bottle) and flows right into the airbox. I have to drain the plug at the bottom of the airbox after about 20 minutes of riding.
i always over oil my filter, as in it drips like crazy on the bottom of the box. imo there is something wrong if you have to empty the rubber after 20 min of riding.
a side question. do any of you apply a thin coat of filter oil to the inside of your box as an added dust collecter?

[kineo3]

KAWSAM62, Do you have the factory Honda extended warranty, or is it from your dealer?

[KAWSAM62]

factory ext warranty ,if those guys wont fix it there not withit try another dealer if you can but get on the phone and let them know your not getting satifaction your a potial futer customer and they need to take care of you if they want future bussiness side note i dont put more oil in the box to catch dirt it always has a little excess from the filter dripping off also if the filter is oiled to much it will make the machine run differnt in my experence always ring the air filter completely out of excess oil good luck:cool:

[YZROOSTINYA]

your wasting oil and losing power if you have oil dripping off your filter, it doesnt need to be saturated, just moist , or lightly coated throughout

[boogiechile]

kineo3, A set of rings should fix the problem if the cylinder wall is still ok, even if you have good compression. As far as a fix without going into the engine, you can do one of a couple of things but the best would be to seperate the vent and intake systems. Remove the vent from the intake and plug the hole to keep trash out. Then run a long plastic or rubber tube (I use the clear kind from the hardware store) from the vent right on the engine up to a place high on the frame and put a crankcase filter on the hose at the top end. You can get a filter about anywhere. Looks like a little K&N pod filter. Zip tie or mount it to the upper frame somewhere. You wont need the res tank anymore. A small amount of oil may seep from this filter but if a bunch of oil is blown out the filter all over your quad (not likely) then you need some rings for sure.

[kineo3]

boogiechile, That sounds like a pretty good idea. I was thinking of something similar, but I like your idea better. I am not exactly sure what you mean by a crankcase filter, is that the official name for it? I am assuming this "filter" will allow air to flow through and not the oil.

[boogiechile]

Thats right, not much oil will make it all the way up the tube and the higher the tube the better. the filter will just bleed or vent the pressure from the crankcase. and yes it is called a crankcase filter. K&N and others make them.

sorry for the late reply, I don't check here that often.

[ChadEXer]

This is confusing for me! Now that I run Methanol in my bike Fast By Gast said I will need a fuel pump to feed Meth to the engine fast enough so I bought one from them. Its a vacuum fuel pump. They said that I can hook the fuel pump up to the crank case vent for the vacuum. I have heard that the crank case vent also pushes air out, which would make the fuel pump not work right. Does anybody know if this is OK to do??

[JD400exrider]

I have seen a few people running a very small K&N filter on the crank case hose. I was told this hose draws air, alrthough if it is considered a breather hose I would think some suction of air has to be coming out. Anyone tried the little K&N type filter on the end of the crank case breather hose ?

[mikeboone]

I do have the K&N Breather filter. The crankcase does indeed push and pull air as the engine 'cycles'. The filter setup will eliminate the dirty air being sent back through your intake as this air is warm-hot and hot air doesnt make power albeit in small quantities. You can check Auto Zone or Advance Auto in the 'import performance' section. They have a cheap knock off that will work in place of a K&N. You just leave about 3-4 inches of rubber hose and connect the filter.

[ChadEXer]

Mike, what did you use to block off the hole in the intake boot??

[mikeboone]

I still have the white plastic hooked up to the air boot with the open end taped off.