engine breather problem. FE650

I was just pointing out a known issue regarding the cam follower bearings. I did the above other work as preventative maintenance. Changing out the valvetrain components is cheap (kind of) and easy insurance.

At high rpm oil WILL collect in the airbox, especially if the level is too high.

The only way it can get there is up through the breather.

Drain a little oil out of the engine so it's just barely visible in the glass when dead cold. About 3-4mm up the glass max.
That's where I've always ran my oil level. Your bike must be perfectly level when checking the level.

Idle said:

I was just pointing out a known issue regarding the cam follower bearings. I did the above other work as preventative maintenance. Changing out the valvetrain components is cheap (kind of) and easy insurance.

At high rpm oil WILL collect in the airbox, especially if the level is too high.

The only way it can get there is up through the breather.

Drain a little oil out of the engine so it's just barely visible in the glass when dead cold. About 3-4mm up the glass max.
That's where I've always ran my oil level. Your bike must be perfectly level when checking the level.

Click to expand...

okay, right now im making my own breather, with a filtre and a catch can.

that did not work at all, the bike didnt run good at all, and the damn filter fell off, and engine oil came out of the open tube all over my engine..

im thinking now it has to be the piston rings, thats the only logical explination. im gonna order a new piston kit and hope to change it in a weekend..

Step away from the motorcycle and take a deeep breath.

When your breather was as stock, did you try riding while keeping the revs down?
Did that keep the oil out of the airbox?

The black course foam filter, it needs to be placed above the rear part of the breather y-pipe. If it was smashed down in there, it would let oil right past it.

I'd suggest setting it up stock, as it was and adjust the oil level until it just shows in the window.

You can rebuild it later if you want to, but it won't fix your current issue.

Idle said:

Step away from the motorcycle and take a deeep breath.

When your breather was as stock, did you try riding while keeping the revs down?
Did that keep the oil out of the airbox?

The black course foam filter, it needs to be placed above the rear part of the breather y-pipe. If it was smashed down in there, it would let oil right past it.

I'd suggest setting it up stock, as it was and adjust the oil level until it just shows in the window.

You can rebuild it later if you want to, but it won't fix your current issue.

Click to expand...

yeah, if i keep the revs down theres no oil in my airbox, its only after i ride it really hard, like if i have a long straight and i give it full throttle and and do 170-180 kmh so that im at high rpm for a long time, thats when the oil is spitting.

what do you mean if it was smashed down in there ? i took it out to check it, and it had clear marks from the pipe from the frame, but it didnt seem unfonctional. but i have never seen one in perfect order so maybe im wrong.

do you think my problem is this foam filtre ?

am i the only one who thinks my problem is because of compression blowing past the rings ?

Idle said:

Step away from the motorcycle and take a deeep breath.

When your breather was as stock, did you try riding while keeping the revs down?
Did that keep the oil out of the airbox?

The black course foam filter, it needs to be placed above the rear part of the breather y-pipe. If it was smashed down in there, it would let oil right past it.

I'd suggest setting it up stock, as it was and adjust the oil level until it just shows in the window.

You can rebuild it later if you want to, but it won't fix your current issue.

Click to expand...

the filtre was gently placed inside the tube, right underneath the frame opening.

im feeling helpless. rerouting the breather tube made my bike run like ****. and everyone agrees its not because of blow by past the piston rings. and no one can give me any ideas about what the problem is.


i see other people having similar problems with their 650's but it seems like their only problem is that their curiouse why theres oil in the airbox. my bike starts coughing and almost skipping beats because of it after i do top speed tests.

if i ride normally theres no problem, but if i accelerate evenonce up to 105-115 mph the bike starts coughing and i find a pool of oil in the manifold and the inside of the frame is soaked.

please someone tell me what the problem might be, and dont tell me whats not the problem -.-

i thank you all for every idea, even if you are wrong someone might be right! because my best guess is blowby of compression past the rings, altough i hear no slammering from the rings and the bike runs properly untill the oil reach the carburettor.

today the bike have been parked all day and i havent even tried to do anything. im out of ideas, i took my old bike without a licence plate out for a ride yesterday just to ride a bike that runs clean. and parked the bike to take some photos, a long way from town. and when i turn around the cops are right behind me. im not in a very good mood anymore. my yamaha runs like a dream but the cops didnt really like me riding it-.-

When I got my bike, it had the same problem. Oil would collect in the airbox and it had a puddle at the intake boot.

That puddle was just what was unable to go through the carb to be burned. I wasn't too worried about it, but still didn't like that it was burning the oil that the breather allowed into the airbox.

It used quite a bit a few times when doing long highway trips. If I remember correctly, about 100ml per 4-5 hours is what I had to replace. Even if just riding normally I would still have to add a little oil before it was time to change it.

My solution was to install a one way high speed check valve referenced in the thread I linked in my previous post.

I blocked off the frame and the rear breather port on the valve cover with a rubber cap. Then used a short piece of heater hose from the front port to the check valve, and another short hose to route it to the right side between the tank and radiator.

I fitted the black course foam in the top of the upper hose, and used wire to retain it. The wire goes through the hose and the filter. I also had to ziptie it back so it didn't contact the radiator. Here's a pic:



I had a K&N breather filter on the end, it was glued and ziptied, but it fell off and got lost. That's what the white stuff on the hose is. (where I had glued it)

The only drawback is that in wet weather, (riding in the rain) moisture causes the black foam to collect oil vapour and it plugs it up a little.

It's not a big deal, I just pull the whole thing off and clean it in the sink with hot water. In the wet months, at every valve check (30-40 hours), I clean it. Sometimes it needs it a little more often. (20 hours).

The check valve stops the in-out pulsing of air that is from the piston rising and falling. It allows air out, but not in.

This creates a slight vacuum in the crankcase. So, once running and under vacuum, there is far less air going out. The pulses of air are absent due to the vacuum. With no in-out pulses, there is no oil escaping.



I don't ever bother adding any oil, as it just burns a tiny bit now. Not enough to worry about. Maybe burns 50ml by the time 10 hours is up and I'm changing it at that point.


IMO, that's the best fix.

i dont think thats a fix for my problem, you too never had a problem with the engine burning oil you said, mine starts coughing and runs like **** !

i tried to make a seperate breather with a kn filter and the rear tube blocked. but that made me loose alot of power !

if rerouting the breather hose as i described earlier makes the bike run like dooky, then there is a problem elsewhere. you could completely remove the system, and other than getting oil all over the place, shouldn't affect how it runs. the main reason it was originally routed to the frame was for neatness and an efficient way to reburn any oil mist. it became a problem as the rings wore. a simple hose routed in an upside down U does nicely.
if the bike runs poorly at wfo throttle, look at your jetting.

i can assure you that my jetting did not change while i was doing the breather mod

i checked the carb, when i took the bottom pkug of the carburettor out the jet came falling out aswell , so i screwed it properly in, and now that problem is fixed. but its still getting oil into the filtrebox, i talked with another guy i know that has a 650 and he said he never had this problem, he has a 2006 mod.

maybe i should try to make my own breather again xD but i think its weird that he doesnt have this problem and i do, and still people tell me to just modify the breather instead of finding out what the real problem is

after you fastend the jet in the carb, does it still run bad after full load-runs ?
or is it only the "a bit of oil in the frame/carb" problem left ?

P-son said:

after you fastend the jet in the carb, does it still run bad after full load-runs ?
or is it only the "a bit of oil in the frame/carb" problem left ?

Click to expand...

now it runs fine again, but the " a bit " of oil in the frame/carb is the main issue. it makes the bike cough and ****. im gonna do a engine rebuild because there has to be something thats making preassure in the crankcase and im guessing the rings.

you know what happends if you put oil into the carburettor right ? the spark plug doesnt really like that. and when your spark plug is constantly getting oiled up that is a very irritating problem !

Re: Sv: engine breather problem. FE650

Ok, nice.

Cant you try to do some cind of catchtank on the breatherhose that prevents the oil from gettibg into the frame but still gets vetliated?
From the catchtank you can then lead the oil back to the engine?

// Andreas/P-son
using Tapatalk 2

Re: Sv: engine breather problem. FE650

P-son said:

Ok, nice.

Cant you try to do some cind of catchtank on the breatherhose that prevents the oil from gettibg into the frame but still gets vetliated?
From the catchtank you can then lead the oil back to the engine?

// Andreas/P-son
using Tapatalk 2

Click to expand...

interesting idea, but why not fix the problem instead ?

$$$$

I think it says in the book not to hold it flat out for long time in top gear.
I have a 08 450 and if i hold it flat out on the road racing a mate back to our cars on the road at the end of the day she will toss oil up into the carby, so when i wash it and fire it up she blows white smoke like as if she is rooted. but it's just oil sitting pooling before the carby. he has a 07 650 berg but does not have a problem at all with his and it has about 12000km up on it. his is higher geared and not reving as high as mine and this maybe why he does not have the problem.
If i fanged it real hard on the tracks from new it would blow smoke as well. so i would only put about 800 ml of oil in it and that helped a lot. but 800 ml is f all :cry:

Some oils may be more prone to climbing up past the gorge into the airbox as well i thinks.
I think it can be a combination of blowby and type of oil but this engine is not meant for holding flat out for long runs and she has only f all oil.
Maybe if the air filter is cloged more so, that may help suck more oil into the air box. :? i hate that as well so i just don't hold it flatout on the road any more. :angry: