YS engine questions.

[Bamm-o]

Hey FG peeps.

I bought a YS 91AC engine from a clubmember that I am going to be using in my Hanger 9 Spitfire. I have a few questions about this engine.

Question #1: This engine has a funny looking piece that is sandwitched between the regulator housing and the bottom of the engine case (see pictures) what is it and what does it do? It's not stock thats for sure.
Question #2: From looking at the stock engine diagrams, there is supposed to be 4 nipples total on the engine. There is only two coming out of mine and where the other 2 are supposed to go they are pluged with a scew (see pictures). I'm guessing that funny looking piece replaced the nipples with the piece's own nipples coming out the side of it (see pictures)
Question #3: What prop would be best for performance and fastest speed? I want this thing to be fast .

Any help will be appriciated!

EDIT: I just read somewhere on the internet that if you screw the diaphram screw to tight it will mess up the diaphram... I did scew the diaphram screw untill it stoped and didn't go any farther or didn't put any hard torque on it. I just wanted to count how many turns out it was. did I scew up my diaphram?

Thanks!

-Dan

[3Dguy]

Interesting, I never had a YS. Keep us informed!

[MikeS]

Someone has made some modifications to your engine, for whatever reason. I have a .91FZ and a 91AC and they have 4 nipples each. As far as I know no one modifies these engines to make them run better, except maybe YS performance themselves, and I'm sure they did'nt do that to your engine.
Have you considered sending that engine to YS perf to get it restored back to normal?

[BreadBowl]

Dan,

I know this is late, but hopefully I can answer some questions for you.

Get rid of that block, and put the nipples back in their correct places. I have no idea what on earth that could have been used for. Make sure that the nipple holes just have screws in them, and there's nothing on the back side that could prevent fuel flow. I doubt anyone could get in there and put anything on the backside, but be sure that nothing got in there.

Also, if you're worried about your diaphragm, check it. If it's torn, you tightened it down too tight. More than likely you didn't since you just screwed it in all the way, and didn't tighten it further. You do need to make sure that it's readjusted before you try and run the motor. Make sure the screw is flush with the case.

I won't be very good at reccomending a prop for speed, I'm sure you can search around.

Lastly, I would strongly reccomend that you send that in to Richard at YS. If it has been sitting for a while, bearings may be bad, gaskets and o-rings may need replacement, and who all else knows, especially with that retrofitted block. Good luck with it.