Gas blowing out of breather.. please help!!

Bike is a 81 yamaha maxim 650.
I got rid of air box and putting on the pod filters. Already jetted the main jets, pods are on there way.. I go to try it out.. start the bike.. and gas starts blowing out of the breather (i cut the og tube that went to air box and put a small k&n filter at the end)
Please someone tell me what is going on here. Thanks in advance for your help I'm learning as I go
cheers!

 

I'm going to assume you mean gas as in exhaust gas.

This probably is the cause of piston ring blow by. You probably only noticed it because you cut the tube. Your rings may be worn to the point exhaust gasses are passing past them, and into your crankcase.

 

What you mean exhaust gas? It was just fresh gas coming out. Like a a lot of it..

 

Wouldn't that make it just leak out of the carb? Ok I'll check it

 

Well, you said gas blows out of the breather, I didn't realize you meant fresh gas, instead of exhaut gas, or another type of gas. I've seen it happen with exhaust gas and worn piston rings where exhaust gasses actually shoot into the crankcase and come out the port.

My suggestion is to change your oil, because gas coming out of the crankcase breather means your oil is also contaminated.

 

Do this: http://www.xjbikes.com/forums/index.php?threads/in-the-church-of-clean.14692/

There are many causes for fuel getting into the crankcase, and all of them have to do with a combination of dirty carbs, and a petcock that needs to be rebuilt.

You also need to read: http://www.xjbikes.com/forums/index.php?threads/the-information-overload-hour.27544/

Get the valves into spec, clean the carbs, rebuild the petcock, replace the brake lines, pads, shoes, and rebuild the master cylinder.

 

I always thought that after removing the breather tube from the crankcase to the airbox (and then adding a breather filter) would always result in some visible vapor/fumes coming from the breather filter.

It was my understanding that these are the fumes that would normally be cycled back into the airbox, and so seeing them come from the breather is a normal occurrance after removing the hose...

 

Gas was blowing out of the breather. .a lot of it at a time

 

Starting to regret real quick here on going to pod filters ... should had left everything stock
quite a hefty read There. . bit overwhelmed. . I really don't want to bring it in to a shop..
I cleaned out the carbs already. . Changed the main jets.. as for the petcock rebuild you can just clean it? How would that affect it coming out of the breather?
Brake lines. . Master Cylinder. . Pulling my leg here??

 

Change it after iv identified the problem?

 

Frenchtracker: I am not clear on exactly which "breather" you mean. The tube that is spewing fuel, where exactly does it originate? The tube that is often referenced on this forum as spewing fuel due to bad petcock and/or float needles is the AIRBOX drain tube, but you have removed the airbox, right? And you have put a filter on the crankcase breather which came up (formerly) to the airbox. There are also fuel line and vacuum line from petcock to the carbs and intake. I just want to make sure we're on the same page here for diagnosis before I put in my over-priced two cents. And which Vancouver are you in? I live between them.

 

it is the crankcase breather.
I'm in vancouver b.c

 

If it's the crankcase breather, then your engine is full of fuel. You should absolutely not start your engine. Pull the oil filler cap and give it a sniff. Smell like fuel? Gulrock is right. Change your oil and filter BEFORE you run it at all. Check your float needles and their seats and replace them if necessary. Also put a fuel filter on the line from the petcock as your problem may just be crud from the tank holding a float needle open. This shouldn't discourage you from doing pods, it's unrelated to that choice. They are old carbs and need some love now and again. That said I think there are other good reasons not to do pods. I got my bike for $300 because of exactly this problem and all I did then was flush them clean and install a filter. It's all been good for 3 years now. You can test for which needle/seat is leaking by using some clear hose on the bowl drains like you're doing a fuel/float level test on the carb; and putting the petcock on prime. Expect to spill some fuel in the process. Do one at a time. On prime, open the drain screw. The needle should seat, stopping the flow of fuel beyond the float level spec (3mm below the bowl gasket IIRC, better look that up). Better check if there's any fuel left in your tank, too. And switch it off prime when you're done. One good thing about pods is it's way easier to get the carbs off at least. Good luck. BTW, I'm just across the line, in the south end of Bellingham.

 

One more thought. You re-jetted. Did you put the floats back in upside down? Or do something else a little off that has the needles not closing? You wouldn't be the first.

 

so the "gas" you are referring to is not gasoline, but crankcase vapors? it sounds like you are getting a lot of blowby past the pistons. meaning the rings are bad (a compression test and or a leakdown test might be in order). does the vapor smell strong of gasoline?

FU

 

is this the filter you are talking about? And which is the correct floater position?

 

I am not talking about the stack on the petcock in your hand. I think it looks like there is an inline fuel filter on the hose exiting the photo to the right, toward the top. That's what I meant. More importantly though, in that photo, it appears that the float nearest your hand is upside down. That would either never let the float needle seat or it would never let fuel flow, not sure which, but it sure as hell won't work.
This is an awesome writeup that may help you: www.xj4ever.com/setting%20fuel%20levels.pdf

 

yeah theres a filter on that already maybe get a new one?
yeah i know the first one is incorrect just checking haha

 

The crankcase breather is on the left hand side, and is near the gear selector.

If you have gasoline blowing out of it, then you will have contaminated oil. You must change it before you start your engine. This problem is related to the carburetor, or petcock . Since you put pods on, the only why gasoline is getting into your crankcase is seeping past your pistons.

If you have exhaust gases coming out of the crankcase breather than you have engine blow by, which constitutes an engine rebuild.

 

I haven't put the pods on yet.. that wouldnot affect it would it?
Also how do you rebuild the petcock
only thing I did to the carb is clean it and put it bacK together.
deff gas in the oil I'll change it.. but ill have to keep changing it every time I start it up if the problem isn't fixed ha..

 

This is an interesting topic. So, gasoline (LIQUID) blowing out of this breather tube (Or Filter, whichever one might have installed) is obviously bad, and deals with a bad petcock and/or leaky float bowls that allow gas to accumulate in the crankcase.

But visible vapor (GAS) exiting the crankcase breather filter constitutes an engine rebuild?

If I'm sitting at a red light and looking down at my crankcase breather, and I give my bike a bit of a rev, a little vapor can be spotted leaving the filter. This constitutes a rebuild?!

Sorry, this is becoming confusing because I'm not sure if we are talking liquid gasoline, or gas gas.

 

It's gasoline. Liquid pissing out.
What would be wrong with the petcock..dont really understand the prime on it.. you need to get a new one or what?
As for the float bowl.. How would it leak?
sorry for my lack of knowledge

 

The stock petcock lever has 3 positions. ON, RESERVE and PRIME. ON and RES are vacuum feed and draw from that whitish stack that sticks up into the tank. ON draws from higher up and when the fuel falls below that, you switch to RES and fuel is drawn from down lower. The vacuum feed means that the hose that comes from a nipple on top of one of the carb intakes must be hooked up to the petcock and, with vacuum from the intake action, it "opens" the petcock and fuel flows. PRIME is just gravity function. Open the tap and fuel flows with or without vacuum. It is there to prime your carbs after an overhaul or running out of fuel. Your petcock MAY be fine. If it's just been on prime the whole time, and if a float needle isn't sealing, then you get an engine full of gas. That's a carb fix. Do this: put the petcock back in the tank, hook a hose to the bigger nipple on the petcock and into a container, move the lever to each of the three positions. Hopefully ONLY on prime does fuel flow. It should take connection to a running engine for fuel to flow on the other two settings. Do you have TWO hoses from the petcock to your carbs and intake?

How about a picture of this breather that is pissing fuel? I am still not quite sure that we're all on the same page. Some think you might mean something different from where I'm going. And a bunch of these guys definitely know a LOT more than I do.

 

May have found the problem.. dont know if related to gas out of breather but what I'm thinking is might have had it on on or res. . Never had a bike with prime so didn't know what was for.. so If I fill er to the top ... it shouldn't leak out on on or res? Just prime? makes sense

I'll do an oil change.. gotta wait for tomorow to get a oil filter.. Also what kind of oil do you use?
And I'll just try again tomorow see what happens
here's couple pics

 

I'll go back to my first post in this thread.

You will keep getting raw fuel in your crankcase until you remedy the problem with your carb(s) float valve(s) not shutting fuel flow off.

Use any JASO MA rated oil of 10W-40 or similar weight. I prefer Shell Rotella Triple Protection 15w-40. 20W50 is a good summer choice.
http://xjbikes.com/forums/index.php...orrect-oil-for-a-wet-clutch-motorcycle.43702/

Also I would like to repeat with great emphasis:

You did not buy a ready-to-ride motorcycle. You have 30 years of maintenance to catch up on.

Do not "try again tomorrow." Become familliar with the machine. Inspect it to find out what it needs. Fix those things, and then you can go riding.

 

This might not be exactly the same as yours but....

http://www.xjbikes.com/forums/index...ng-the-yamaha-vacuum-fuel-valve-w-pics.25058/

And you will probably need to do your throttle shaft seals and fuel rail seals.

http://www.xj4ever.com/hitachi throttle shaft seals.pdf

And then your gonna need to set your fuel levels.

http://www.xj4ever.com/setting fuel levels.pdf

If you haven't your gonna need to do your vavles at some point. This should be done first most likely or at least checked.

http://xjbikes.com/forums/index.php?threads/airhead-valve-adjustment-with-pics.14827/

And you will need to do your brakes. Front and rear.

And I probably forgetting something. But...

You have a old bike and it's gonna take some work to get it running correctly and safely. You will be rewarded with a fun bike when your done.

These links can all be found in the diy section of this site. Compliments of the great people from this site.


Good luck and have fun!!

 

Slow down the advice. There is nothing to indicate that either the fuel rail o-rings, or the throtttle shaft seals need to be replaced (though there is no harm in doing so proactively).
One step at a time.

 

Ditto what K-moe said: "You will keep getting raw fuel in your crankcase until you remedy the problem with your carb(s) float valve(s) not shutting fuel flow off."
You're about to waste a bunch of oil and time by hooking up bad carbs and dumping fuel into the engine. And you don't need to FILL the tank to test the petcock. Just a little will do. A full tank will make next steps more difficult. The petcock having been on ON or RES is not a problem. That's how it is supposed to work. You need to get diagnostic. Positively identify the problem with the tests suggested. Fix it. Then change oil and fill tank. Then ride a little cuz it's fun. Then do as much of the other maintenance as you can stand. It is all good stuff to do. And I ain't going anywhere near the dreaded "which oil" question. Do use some though.

 

Update...
filled tank up. Petcock is good. Only comes out in prime mode

Fired er up quickly.. revd up real high so I shut it off.. Gas and oil spewing out again of breather

Took the carb out. Looked in bowl and only 1 was fully flooded. Other ones were dry or half dry (tthe float)

The seat on that one.. The filter at the end didn't sit flush onto seat.. maybe that may be the problem. And part of gasket is cracked minorly

Will get new parts for it see what happens thanks for all the help guys

 

Back to what k moe said---
You have raw gas coming out of the tube. You MUST FIX THE PROBLEM.

The ONLY way the gas can get there is via the crankcase, which will also dilute your oil

The ONLY way gas can get into the crankcase is by running past the cylinders in great enough quantity to fill up your crankcase with that much gas.

The only way it gets to run past the cylinders is to fill the chamber with enough gas to run through

The only way it gets to the cylinder is through the carb. Good, accurately set, float valves stop the fuel flow regardless of petcock.

The only way gas gets to the carb is through the petcock.

SO..... If you left it on PRI, good floats would have stopped the flow anyway. Therefore you DO have a float issue/fuel valve needle issue.

You MAY have petcock issues, but that becomes secondary to the floats/fuel valve issue.

Petcock settings:
ON-fuel flows only when engine runs
RES-fuel flows only when engine runs
PRI-free flowing all the time

This is NOT a Pods issue......

 

You also have a maxim 650?
Do you know the float level? And do you measure from surface where gasket sits on to the top of float?

 

Float level is 17.5mm from gasket surface on carb body to highest point of floats.

 

But only as a starting point.

Correct fuel level is critical, and cannot be achieved by measuring float height alone. The floats must be wet-set. You only have +- 1mm of fuel level to play with before the level is out of spec. It only takes a very tiny change in float height to move the fuel level that 1mm.

http://www.xj4ever.com/setting fuel levels.pdf

 

Minor correction to that-- it only takes a very tiny change in float tang adjustment to move the fuel level that 1mm

 

That's what I typed. How did it get into your post and not into mine? Darn internet gremlins

 

Thanks dudes! I set it all roughly to 17.5 except one of the floats is Basicly bottomed out.. doesn't sit like the others with some play.. bought new seat and needles .. tried putting different needle and it was fine so it must be a faulty needle?
Also what is wet set?
And I thought I read somewhere that the gasket had to be removed so it wouldn't be on the surface of it..?

 

For wet set you need to get some clear 6mm tubing and place it over the nipple on the front of the carb bowl, tape the tubing along the side of the carb body. get the carbs completely level side to side and forward and back, set your petcock to pri, unscrew the drain plug from the side of the carb bowl and check the level at which the fuel stops along the side of the carb. I forget what the measurement should if someone could fill him in. but you need to check where the fuel comes up to and measure that height, i think its like 3mm from the gasket surface? (don't quote me on this i'm probably wrong). And if it's lower or higher than that then you need to adjust the float by lightly bending the float needle tang up or down. Make sure all your floats are installed the right way, in the picture you posted of your carbs one of them was upside down. someone mentioned the piston rings a couple time which could definitely be a posibility if gasoline is getting in your crankcase. I dont know how to check that but im sure someone else could tell you.

 

He already said he knew the one float is shown upside down... As far as rings--- if there is gas in the crankcase, the only way it can get there IS BY SEEPING PAST THE RINGS. ( well, I guess someone COULD pour gas in through the oil filler cap.....)
That doesnt mean the rings are bad though.... Raw gas pooling in the cyls will seep down. But, get the gas problem corrected, make sure valve flearances are in spec, then do compression tests/leak down tests to determine cylinder chamber/piston rings conditions.

 

my bad, icouldnt remember if someone said something about it. Has anyone mentioned getting a service manual? it helps a shit ton

 

Don't need a service manual to diagnose this .... It's been explained several tines

 

He should still have one

 

When you say 3 mm from gasket surface... you mean where the gasket sits on? Because obviously couldn't see where the gasket is once the bowl is bolted on.
I've set the height already I'll try wet setting it today

 

No.... All measurements are taken from the carb body platform surface, not from on the gasket sealing ridge.

 

here's picture of the fuel level section in the haynes manual. sorry, i was at work and didn't have access to the book.




hope this helps.

 

this is why i told him to get a service manual so he can do procedures like this without making new threads, almost all the info he'll need for future work can be gotten from this book. Not trying to be stubborn, just making a point.

 

Or people could read the link that I posted on how to wet-set floats. It has pictures and everything.

 

Drained the oil.... I'd say 75% gas :S
Any thing I should do to make sure it's all gone ?

 

Do another oil and filter change within a few dozen miles after you have it running.