[Cougar429]

Not so much. You can move things around inside the fuse, (battery, etc.) to balance out the weight of the motor if it throws lateral balance out, but adding just a slight amount to one wingtip works just as well or better.

[OLD PRAIRIE RED NECK]

The reason That I chose to mount the engine inverted on my Slow Poke (see avitar) was to lower the vertical center of mass so that it would be closer to the center of lift. By mounting it inverted you not only lower the weight of the engine but also you have to lower the fuel tank and it's associated weight in the fuselage. A double advantage!

Now I must admit that on this plane it is probably a bit over kill to worry about but you pattern guys know what I'm talking about! It helps make the transition between upright & inverted flying more neutral.

The only down side I have experianced with it is the glow plug is in an awkward place! Could be fixed with a remote connection though...

[Generalwolfe]

Can I kick this thread open again with a question? I am trying my first 4-stroke - a Saito 62 - and the only way it's going to fit is inverted. It's a tight fit but not bad and the cowl trims nicely for goog ventilation. By the way, it was the information in this thread that encouraged me to go this route. The one concern I have is that the crankcase vent nipple now points up instead of down. Is this a problem? Should I run tubing from it to direct it downward? When I had the engine on the test stand for break-in a fair amount of oil drained out of the crankcase through this nibble. In the inverted position how will this residual oil drain?

[JKovats]

That's a great question that I don't thing there is a written answer to. I have a bunch of Saitos upright, sideways and inverted and the nipple on the newer ones points in many different directions. Never had a problem.

That is a vent line and develops a fair amount of pressure when the enginge is running and I believe it will blow any excess oil out.

There are no cautions about this in any Saito literature that I have ever read. If it mattered, I believe Saito would say so.

[Cougar429]

Only recommendation on the vent line is to keep it short or go with a larger I.D. tubing as close to the engine as possible. If too long and/or too small an I.D. it will simply keep cycling the bypass oil back and forth and not drain properly.

Here is a pic of the Saito 125a installation in Rare Bear. The large diameter cowl mandated the drain run to where it can exit.

[Generalwolfe]

Thanks Cougar, but the picture you attached shows the crankcase vent on the backplate, so regardless of the engine orientation, the vent is always in the same place. On the Saito 62 (and I believe on most of the more recent Saito single cylinder engines) the vent nipple is on the bottom of the crankcase pointing straight down so when you invert the engine the nipple points straight up. To drain the the crankcase out the bottom of the cowl I will need about 8 inches of tubing with 180 degree bend in it. I could try and vent it to the side as that would only require a 90 degree bend. Your comment about longer tubing requiring greater inside diameter - this gets at the heart of my concern. Throw in the 180 bend and I worry there will be inadequate venting.

As JKovats points out in his comment, Saito literature is silent on the issue. But that literature does say a 4 inch length of tubing can be attached to the nipple. Does that mean that more than 4 inches is not recommended??

[Cougar429]

Sorry, perhaps I could have been more specific. The pic was added simply to show the larger diameter tubing attached to the vent. This way it breathes better with a longer run to outside the cowl.

In your case the 90 or 180 degree bend would have to be made as close to the engine as you can to prevent as much bleedback as possible. If it is not breathing correctly one indication is oil leakage out the cam housing or valve covers. I imagine you will get a bit from the covers due to the inverted mounting. All my 4-strokes have been side mounted.

One other consideration with inverted mounting, (and one that is pretty much standard with them inside a cowl) is a remote glow connector. It will be a bit more difficult with the glow on the bottom even if not partially covered with the cowl. With remote glow you can mount it in a more accessible location.

[mrrandyman]

Hi Folks,
Good thread.
I have a Saito 82 inverted and it smoke to beat heck. It runs fine but all the smoke has me concerened.
Is it that the oil has no where to go and is being burned off through the muffler?
I just don't want to cook the engine.
Also what would be the smallest twin a person can get.
I think it would look good in another Great Planes Cub?
Thanks
Randy

[RAMJET]

what I would do is go to the field ,find a guy running your intended setup that is having no problems and watch what he is doing .I have never had a 4cycle that would not run better than a 2 stroke in any orientation but starting procedure and engine setup can be a bit tricky for a new guy and this is not something you can teach easily .the best way is to be shown.remember be sure to ask the guy having no trouble. I don't know how many times I have seen a new guy approach a bunch of guys messing with a motor they can't get running and ask them for help, why is this,ask the guy having no trouble.
4 cycle motors are amazing but you need a good teacher .
one piece of advice ,if they pull out a electric starter find someone else.
a 4 cycle will start 1st flip every time without fail unless you are doing something wrong or the motor is too hot.electric starters will destroy a 4 cycle motor in no time and IMO are dangerous if you slip when the starter kicks you off as your wrist will likely go through the spinning prop.

a few pointers - use only OS f-plugs /use only 4 cycle fuel ,2 cycle with the same nitro has too much oil, I found coolpower green to work well/start engine only by flipping engine backwards, bouncing the prop against compression.(but get help, don't try to learn this yourself) if you see someone starting there engine this way ask for there help.

[OLD PRAIRIE RED NECK]

Originally Posted by mrrandyman

Hi Folks,
Good thread.
I have a Saito 82 inverted and it smoke to beat heck. It runs fine but all the smoke has me concerened.
Is it that the oil has no where to go and is being burned off through the muffler?
I just don't want to cook the engine.
Also what would be the smallest twin a person can get.
I think it would look good in another Great Planes Cub?
Thanks
Randy

Question #1: If it's smoking, it means it,s getting lubed! When it stops smoking is the time to be worrying about "cooking" your engine! All glow engines should show a little smoke trail in the air.

Question #2: Saito .60 twin. Great running little engine!