Does anyone here know anything about a YS engine? This is a learning curve for me.

I bought the thing used and in great shape but the guy i bought it from could not get it to run. I found it to be a challenge.

I got it and replaced all of the gaskets, diaphragm, reset the valve clearance to between .004 and .01, and and did a thorough inspection. I then got on the net and found all the settings for the needles and regulator and set up the check valve pressurized fuel system. Used a syringe to check for leaks.

I fueled the tank up and started right up and ran like a dream for a min or two. As the fuel level started to drop the engine began to richen up. I chased the high speed all over the place and I could not get it to run correct. The engine bogged and died. I fueled it up again and again she ran great at first. then back to the same routine. I think that it either is a heat problem or something with the screwy fuel system.

I called a guy over to look at it that has been running YS engines for a while and he could not figure it out.

I just hope this rings a bell with someone.

Thanks to all

It sounds like a wimpy tank. Get a good solid tank behind it like a Hayes and it will likely solve your problem.

This engine was on my funtana 90. I might agree with the tank there but it does the same on my test stand and different tank.

Say again what you set the valves to. .004 inch or mm? They should both be at .003 INCHES.

Fuel type?
Prop size?
Plug type?

Before I set them the valves where at about .025. I have the OS valve adjust kit that has two shims. One is .004 and the other is .01. You should be able to fit the .004 and not the .01. They are now tight on the .004.

When on the Funtana I tried a APC 16X4W and on the test stand Im using a MA 15x6.

Fuel is Omega 15% I understand that this engine likes 30% 20/20 fuel.

OS F plug

Thanks
Andrew

That fuel should be fine. I run 15% Cool Power on all of my YS engines with no problem.

The Omega 15 isn't a good choice. Go to YS 20/20 or 30% heli fuel.

Get a piece of .003 shim stock or feeler gauge and use that in place of your OS shims.

Going to try Wildcat 2&4 15%. Can you explain why Omega 15 will cause to results that I am getting.

Gona do the .003 shims.

Tx

The Wildcat 15 probably won't work either. Go for the right fuel.

Dave

For some reason I'm thinking that Im getting to much pressure in the tank and it is flooding my engine.....

I understand your fuel concept but I have a friend that runs the same fuel in the same engine and no problems.




Tx

The pressure in the tank varies from engine to engine. That's why they have an adjustable regulator.

Go to www.ysperformance.com and follow the running instructions. If you can't figure it out from there, maybe you ought to have service look at it.

Dave,

I think i may have found the problem. In the regulator assembly there is that brass piece that looks like a valve with a flat top. The one the diaphragm rest against. Anyway, the total length of it was .013" longer than a NEW spare that a friend has. Being longer has a longer stroke, thus pumping more, thus flooding the engine.

I knew it has something to do with the regulator after I turned the screw in to its hard stop and it was still bad rich. I did a test that someone mentioned. He said that when it starts its rich problem unhook the pressure line and see if it goes away. It did.

Andrew

Keep us posted.

Well I finaly got a chance to run it with the shorter regulator "plunger" installed and that fixed the problem. Now to get it to run I have backed the reg screw out about a 1/16" past flush. I had to do that to get it to idle.

It runs fine in a mid throttle flight but it can not sustain full throttle for very long. Now it seems lean around the midrange and maybe lean on the highend.

Ant thoughts.....

You can fool around with and throw parts at it FOREVER, but a quick trip to our service dept. will get it fixed right the first time. Consider sending it in.

YS Service
1295 Industrial Court
Gardnerville, NV 89410

Phone 775-782-4562

Will this engine (91ac) handle a APC 16X4W? If not, what prop for a Funtana 90?

Thanks
Andrew

Maybe a standard 16x4, or maybe a 16x4W if it's a good 91. Shoot for 9000 to 9500 peak rpm.