oil leak

[guyom]

i've got a question.. i remove the airbox from my R65 1981 and put some K&N filter. Work properly just need to adjust the carb. Then, but it was here before, there is a hose that come from the carter air hole (on the put of the motor when you remove the cap on the motor which protect the starter etc... so i put a air filter also on that hose... (after cleaning everything) but i always had a bit of oil leak from that hose... come from the motor... so question :

it is normal... too many oil in the motor (i am just above the minimum) ? i changed the hose long time ago : it is too short ? I do not understand because there is a piece of metal that protect the hole when you remove the piece where the hose is locked on (ouf... hope you follow me again ;-)) i mean i think to prevent oil leak.. but no working. I mean after a road trip of 200-300kms i always had oil on the gearbox... coming from this hose...

Any suggestions... (except photos ;-))
i added one picture where you can see on the right the end of the black hose...

Thanks for time,

Guyom

[Bob_Roller]

That hose is for crankcase ventilation .
There needs to be a way to route the crankcase gases, or you will just  end up venting the crankcase into the area around the starter .
Creating an oily mess on the engine  and transmission .

[marcmax]

Guyom, When I took my airbox off I had the same issue. I put a small aluminum catch can to catch the oil vented from the crankcase and just empty it every few months

[mrclubike]

Your best option is to reinstall   the air cleaner and crank case ventilation system and plug the air injection system 

If you have removed the air injection now you need to plug the vacuum ports on the bottom of the carbs  with the screws

You   just screw the screw into the nipple
And remove to balance the carbs

[marcmax]

I never likes the way the black airbox looked. That is why I removed mine, not for any imagined performance gains (doublful). I tried a old style clamshell airbox and while I thought it looked better than the original black one, it also made the engine/gearbox area look like a massive block of aluminum. I settled on pod air filters and a sloping epoxy starter cover.

[guyom]

HI guy thanks for answer. Does anyone tried to do something to end up venting the crankcase into the area around the starter ? I plan to increase the length of the carter hose first to retain a bit the oil.

Also certainly a naive question but can i close the carter hole ? That stops ventilation... and stop oil leak... ;-)but what should be the impact of that ?

[Tony Smith]

Also certainly a naive question but can i close the carter hole ? That stops ventilation... and stop oil leak... ;-)but what should be the impact of that ?

The pressurized crankcase would simply find somewhere else to leak, probably somewhere you would like even less than the current arrangement.

[georgesgiralt]

And if the pressure does not find it's way out, it will slow down the two big pistons coming in in a smooth air cushion fashion... You will have an hell of a job making the engine stay running at idle and it will have... poor performance to say the least.
But nothing beat first hand experience...

[Barry]

The idea of the breather valve is to let air out when the pistons go inwards and not let the air in again when they go outwards.  In a perfect world the crankcase would pump down to a partial vacuum and minimise pumping losses. In practice there is always some blowby past the rings which means always a flow of air out of the breather.

[guyom]

thanks a lot for answers ! i have some ideas for this problem, will try them soon and send you pictures of.

Guyom

[nhmaf]

What can happen without a functioning crankcase vent is that the engine eventually makes one out of the rear main seal.  This is a highly undesirable situation.

Highly recommend keeping the crankcase vent system in place, or using a catch can to collect the blown out oil mist if you don't want to burn it by routing back through the carbs in the original design.

The engine is a big compressor/air pump, remember, and there is air on both sides of the pistons..