Carl.E

I tore down my YS 91FZ to look it over after it had been acting up and not running descent, which in turn caused my G-202 to crash. I ordered a new diaphram and a gasket set. My question is this:

In putting the cylinder head back onto the body, is there supposed to be a clear plastic gasket that goes between the two? They gave one to me in the set, but there isn't mention of one on the exploded parts drawing. And of course I don't have the faintest idea if I took one off when I took it apart. It makes sense to have one there, but since it's not included on the exploded view should I leave it out? I'm not sure what to do...or could it just be a head-shim for using really high nitro?? The gasket set is actually for a 91AC, but it's the same basic design, so maybe the AC used it but the FZ doesn't? I'm not sure. Somebody that knows please help! Or somebody with a 91FZ take a look at theirs and tell me please!
Thanks!

Carl

Traxxas_Tech

My Feedback: (22)

If its hard plastic, its a head shim, if its a soft silicon-like gasket, It mey be needed for sealing the chamber correctly. If you already have the paper head gasket the engine, you dont need that plastic one. If you are running 15-30% Nitro you will be fine. I wouldnt put it on and am comfortable with that decision. I mean, it will not hurt your engine... Hope this helps & good luck, Coulter

Carl.E

Thanks Coulter. It isn't a soft silicon gasket like the other gaskets...it is more of a harder plastic like a shim. I'm leaning towards not using it unless somebody else here knows for a fact that I should...

Carl

deputydog

The previous thread obviously does'nt own YS or he's never taken one apart.
Depending on which generation of YS 91 you own is the deciding factor. The older version has a clear plastic type gasket between the head and the crankcase. The newer version crankcase is beveled and they have installed an o-ring on the outside of the piston sleeve to seal the head and crankcase. Sounds like you have the older style!

Hope this helps.

Traxxas_Tech

My Feedback: (22)

Actually, I have several YS engines, and have repaired and overhauled a few for myself and others, YS 91 included. Dont go bashing other people like that, its hateful, rude, and doesnt make people like you. Just give him the helpful info.
His 91FZ may be either at this point, he hasnt given enough info really. If it shows any flat type gasket at all, it is the older one, if its the new FZ, he should show an o-ring. That why I said leave it out. Mine has the o-ring version and notes it on the exploded view. Since his doesnt show it on the paper, He doesnt need it in his engine. I'm not trying to start a quarrel, please take this as a friendly discussion.

Coulter

Traxxas_Tech

My Feedback: (22)

Carl E:

If you can take a picture of the cylinder liner and head, we can tell you exactly what you should do.

Carl.E

Yes guys, it does have the black silicon rubber o-ring...it is a 91FZ. I have already put it back together without the flat AC gasket, so everything is in order. Thanks!

Carl