I have a Saito .72 on an Ultra Stick and the way the crankcase vent is situated, it makes a bigger mess than the exhaust does. What would happen if I put a "T" in my exhaust pressure line and connected the crankcase vent to the T (the exhaust pressure line)?

You cannot do that.

Just stick some fuel tubing on it and run the vent outside the plane(away from in front of the fire wall) by the muffler.

Jim

You could run a longer fuel tube from the vent and attach it the the muffler so it spays oil in the same place as the exhaust.

I considered trying something similar but decided I didn't want the byproducts contained in the blow-by going back through the engine.

If you were to put a "T" in the pressure line about all you would end up doing is vollying the muffler pressure with the crank in-coming pressure. The crank vent is a two-way valve. As the piston travels towards TDC from BDC air is sucked into the case via the vent. As the piston travels from TDC to BDC ring blow-by and air are expelled through the vent.

Hmmm... After a moment of thought... you would be creating a negative crank vent. In other words, tank pressure and muffler pressure will be forcing air into the crankcase not allowing the crankcase to vent properly. And, when the crank vent draws in air it will be drawing form the tank pressure.

Quite a few variables is this equation!

Since I don't own any Saitos I wonder if that much blow-by normal. If it is new the ring may not be seated yet. If it is old you may need a new ring.

The fuel tubing Jim suggested is by far the easiest option. It will not only divert the blow-by byproducts but also provide a means of lubricating the three front end bearings.

My 72 has the same problem. I thought it was getting better with time, chrome cylinder beaking in slowly, but now I have more than 10 gallons on the engine.

I tried to solve the mess by connecting the vent to muffler. See this pic http://www20.tok2.com/home/rc/data2/...22/html/17.htm

The problem with this setup was that vacuum sucked the valve train almost dry from oil. I checked it after 3-4 flights. In the end I have learned to live with the oil mess.

I was also concerned about having a problem with the ring but I doubt it. When comparing to the rpm figures I have seen here, my 72 seems to be on the strong side. It also starts and idles pefectly.

What are the sings of a bad ring -- nice to know If I choose to dismantle the engine.

On my Ultra Stick I ran an 8" length of tubing from the crankcase vent to the underside of the main landing gear. I secured it to the fuse with a couple of zipties.

Problem solved.

You can try to run a larger tube from vent nipple. You may have to use a connector to do this. But run the vent tube to a 2 oz tank that will collect the oil. Make sure the tank has a vent also. Keep all vent lines short as possible. Hope this helps John

:sunsmiley Depends how you look at it - might be messy BUT oil coming out the breather is a sure sign that the bottom end of the engine is receiving adequate & life giving lubrication. So, that's a positive thing. I for one, am happy to live with the "mess".

However, I have seen photos of modications to some 4 strokes in that the vent is connected (by way of a length of silicone tubing)to a nipple on the intake tube between the carby & the head of the engine. This way, the oil that leaves the breather is "recycled" back into the engine & leaves via the exhaust outlet. A closed loop system. From what I understand, the performance of the engine is not impeded in any way. Seems a pretty neat idea.

You would need to be careful though when tapping the intake tube for a screw in nipple as the wall thickness in this area is not great.

Anyone else tried that modification ??

My ASP FSR120s come stock with a nipple on the intake manifold for connecting with the crankcase vent tube. Curiously, ASP/Magnum's smaller displacement 4strokes don't have this feature. I wonder if it is just a matter of economics or smaller engines don't lend themselves well to this recirculation.

Sure seems like the products of combustion that is in by-passed oil would tend to rust the insides more. I say once it comes out -leave it out- but not all over the enviroment. Just run it into a 2 0z tankCaptin John