I am helping a bud with his FS 90. On the back cover plate there's an area that is extended and you can see a small bearing go around and there is a flat head screw in the middle. You can see that go around too so it is connected to the crankshaft. My question is that this area is all open and could get dirt in it. Is this original or was there a cap over this that I am missing? Thanks in advance for any help. I hope the pictures show what I am dealing with.

Jeff

....you are missing the back cover. It looks like it snaps on.

My engine was in a horrific accident....the reason for the dents.

FBD.

You might could find a "Plug" at an old fashion auto parts store. I doubt that you will be received very well at Pep Boys or Auto Zone though

all you really need is to keep dirt out. The fact that it is missing should have a minimum effect on the way the engine runs.

If you has lathe or someone you know has lathe, it is not to make a new back cap of aluminium and press at place with light press fit.

Thanks!! Great info!! I am a toolmaker and will turn a cap. Thanks again for the help. Jeff

Hi!
Looking at the pictures you showed us the rear bearing has lots of rost and should be replaced (likely all the other bearings too).

With the glowplug facing forward on this engine, are you guys using remote glow or are you using a regular ignighter very carefully?

....I used a remote on mine, had to...the engine was inverted.

FBD.

Thanks Dave. Great pics in both your posts.

I have one of these engines mounted inverted on my mono-wheel taildragger Calypso and have no problem staying out of the prop with a 'standard' short reach plug igniter. Of course you have to pay attention to what you're doing as when starting any glow engine. Besides, the rear of the prop is a bit less dangerous than the front of the prop.

Terry in LP

I'll second that. The bearing you're looking at is the rear cam bearing. I got some hidden rust in that area of my FS .90 once long ago and it got into the valve lifters and stuck them, causing a dead stick at a most inopportune time. That area needs to be disassembled and cleaned.

CR

Hello; For some reason, I can't seem to upload pictures today or you'd be looking at my two OS 90's. I use an alligator clip to light up the glow plug. Attached to my flight box. I also have a few Enya four strokes, so it's nothing new to me. I have lost that back cap. A friend of mine who has a little metal lathe, machined a cap out of a dime and fitted it for me, problem solved. The same fellow made a muffler end cap for me whin I lost that on one of my OS 90's. He just turned out the inside of the muffler a little, then turned down the dime to make it an interference fit, then he set it in place and folded the sticking out aluminum around the dime. He used a dime because a washer costs 29 cents now.

Do your engines squeak

Do your engines squeak