FJ1200 base gasket leaking

[racerrad8]

Actually I was thinking along the lines of a sealed catch can (not vented) This would allow the oil to condensate and collect before routing thru the carbs. Fill the can with scrub able stainless steel to help separate the oil out of the blow by vapor. Have a drain at the bottom of the can where you can periodically drain off the accumulated oil.

We use this set up in turbo Miata's all the time. It works well. Not exactly CARB approved 'thou...

I'm mean, jeeze, we got all this room now that the airbox is removed. We can come up with something.

I'm tired of a stinky bike at stop lights.

Sure that is what you use on the Miata, but you do not put that contaminated vapor in front of the throttle plate do you? If yes, then that would mean the turbo pressure would be pressuring the breather tank too if that was the case.

Maybe we need to re-install the air box which will do everything that needs to be done.

Randy - RPM

[aussiefj]

But I love the induction sound and ease of maintenance with the pods, never happy are we Randy, that's the problem once you catch the 'moditus' virus, but still it's good for business mate.

John.

[Pat Conlon]

Noooooo not the air box.....perhaps that smell isn't so bad after all....

Yes, on the turbos the crankcase vapors are pulled in between the filter and the compressor intake, thru the compressor, thru the throttle plate into the engine.
Folks also run the vented catch cans but they have noticed that the engines seem to run better with a slight negative pressure in the valve galley.

[Flynt]

I'm tired of a stinky bike at stop lights.

Maybe we need to re-install the air box which will do everything that needs to be done.

I had the same "stinky bike" and even had some oil vapor coming out of the vents beside the carbs...  I tried moving the breather back to the tail area, but that just relocated the stink/vapor.  I moved it back to under the pods, and this time made it fit right under the center two (I have 4 individual Uni filters) as close as possible to the carb intakes hoping the blowby would get sucked in through the pods mostly...  

IT WORKED!  No more stink or smoke, just a happy FJ breathing it's own fumes...  Might give this a try Pat.

Frank

[FJscott]

I'm tired of a stinky bike at stop lights.

Maybe we need to re-install the air box which will do everything that needs to be done.

I had the same "stinky bike" and even had some oil vapor coming out of the vents beside the carbs...  I tried moving the breather back to the tail area, but that just relocated the stink/vapor.  I moved it back to under the pods, and this time made it fit right under the center two (I have 4 individual Uni filters) as close as possible to the carb intakes hoping the blowby would get sucked in through the pods mostly...  

IT WORKED!  No more stink or smoke, just a happy FJ breathing it's own fumes...  Might give this a try Pat.

Frank

I did the same thing, zip tied the breather so it was almost touching the uni-pod...no more fumes and with the breather hose almost vertical I would imagine any condensed oil vapor would easily drain back to crankcase.

Scott

[movenon]

That's the way I set mine up also. It is back about 2 inchs from the pods up high, tied to the frame cross brace. Never noticed a problem. 
George

[Pat Conlon]

Ok! Thanks guys, I'll give it a go.....

[aussiefj]

I will give it a go as well.
John

[Fj.itis]

Me too! Hate that drifting smell at the lights.

[FJ_Hooligan]

I knew I read this recently, but I have seen it repeatedly in the general motorcycle literature for several years now.

In the April issue of Sport Rider from their test of the 2014 Kawasaki Ninja 1000, they mention:

"Windows between the cylinder cavities in the crankcase reduce pumping losses at high RPM..."

It may not have been the cause for the original base gasket failure, but it is an issue that engine manufacturers are addressing.

Pat,
The pressure results from having to move air under the piston.  The piston is moving fast and that air has to go somewhere.  If it doesn't move fast enough to the cylinder(s) moving in the opposite direction then pressure will build.  Manufacturers have tried to relieve this by boring holes in the side of the cylinders (near the bottom where the rings never get) to aid the airflow between cylinders, but there's only so much they can do.  The rest is physics.  

I don't understand this at all.

The cylinder protrudes well beyond the casing into the crankcase, the base gasket is not subjected directly to this pressure, only general crankcase pressure.
The cylinder already has a hole to relieve the pressure from the descending piston, a 3" hole directly under it. How can the pressure build when there is nothing to restrict it.
The bottom of the cylinder is open to the crankcase with no restriction, the pressure has plenty of places to go and the FJ is a short stroke engine anyway.
If you've got a 3" hole directly under the piston I can't see how small holes around the base of the cylinder are going to achieve much in terms of expelling air from one cylinder and drawing it into another, unless you're talking extreme performance engines where every 000001% helps.
I wasn't aware manufacturers considered this a problem on production engines.
Then again, possibly I'm just out of the loop with what's going on.

Noel

[racerrad8]

"Windows between the cylinder cavities in the crankcase reduce pumping losses at high RPM..."

Which Yamaha addressed already beginning in 1984...

You can see the "windows" or pressure differential ports between the two outer cylinder cavity webs.

Randy - RPM