Smoke from breather tube?

[reorx911]

Hello,
I have a 1982 gs750e and after a long ride noticed a little smoke accumulating under the gas tank coming from the breather tube (out the filter) running above the carbs. I did top it with a little oil before the ride and noticed the exhaust burning a little oil too. Have i over filled it? or am i crazy and trying to ignore a more serious issue? I removed the amount of oil i added and the exhaust seems to have calmed down on smoking but the breather is still smoking when the engine is hot and running.
Any info would be greatly appreciated.

Thanks guys!

[49er]

Sounds like your breather tract inside the airbox may be blocked. Is the airbox metal or plastic on your bike. The metal ones often form rust inside the tact, eventually blocking off any crankcase ventilation.

What level is the oil in the sight glass, when the bike is on the main stand and sitting on level ground?

[Nessism]

The "smoke" is blow by gas (combustion mixture that is slipping past the rings) plus oil mist. That breather tube is supposed to go into your airbox, or a catch container of some sort if you don't have an airbox anymore. Sounds like your engine is getting a little tired since more blow-by occurs, and more oil burning, when the rings/cylinder gets worn.

[jknappsax]

Check the compression on each cylinder to determine if the rings are at the end of their life cycle; I think that the lower limit is 100 psi. Best to check valve clearances; if they're tight, they may not close completely, giving you false low readings. The 1979 GS 1000 I'm working on read within limits, but low when I first checked them, with one being at 105 psi cold. Once the valves were in spec, the cold readings were all in excess of 180 psi. You may have blowby from worn rings, or there could be water condensate that's evaporating out of the oil once it heats up and comes out the breather. Good luck, I hope you don't have to pull the jugs and do rings and all that entails.

[BassCliff]

Greetings and Salutations!!

Hi Mr. reorx911,

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Thank you for your indulgence,

BassCliff

[reorx911]

Thanks so much for the help guys. I dont have an airbox that encloses the breather. There are individual filters on each of the four carb tubes that are exposed. Oil level is on the low side when in center stand. Ill check compression. Think i should "create" something to enclose the breather?
thanks again guys. Yall rock

[49er]

As suggested, do the compression check. If they check out at 125 psi or better, you're still good for many more thou miles.

Your next check is to see if the cam covers still have the fine meshed gauze filters fitted to them that reduce the amount of oil misting that naturally occurs during high rpm operation.

You should fit a breather filter/catcher to your crankcase vent to control oil misting too.

[BassCliff]

Hi,

From J.C. Whitney:

<<Click the picture.

There are other solutions at other vendors too.


Thank you for your indulgence,

BassCliff