YS 1.20 problems

n-doering · #1 02-14-2010, 02:58 PM

Hi everyone, I am new to this site. I have read through some other forums already and still have some questions in regards to my YS 1.20. First off, I bought this engine off ebay. I have it bench mounted and found the owners manuals online, I have verified the tank check valve is working properly and installed in the proper orientation. I am running Cool Power Heli 15% nitro with 17% syn oil. Now hold on!! I have mixed in caster oil by volume to bring the oil content to 22%. (Higher nitro'd fuel is hard to get around here.) I also installed a new OS F-type plug. My problem is I can get it to start, but cannot maintain a running state. After about 10 seconds, it is like the engine loads up and dies. I have tried to get it to idle and have also tried to start it and open it up, no luck. This is with the igniter left on. Any suggestions on what I can do to get this thing running? One last note. I set the high speed needle valve to manufacturer spec, but I am unsure which adjustment is for the low speed needle. The manual does not state which one it is. Can someone point me in the right direction?

Mike Gabbard · #2 02-14-2010, 09:52 PM

which 120 do you have?

Most likely your Lowspeed needle is the one on the opposite side of the throttle arm a little screw in the middle of the barrel unit. Set the low speed for idle and high speed for top end power then use the pump screw to set the transition. Dont try to set the transition from the lowspeed needle like other glow engines.

One more thing the Low speed needle mat be backwards in the way you need to turnit to lean and richen than other engines; example you may need to loosen the screw to lean the lowspeed.

n-doering · #3 02-15-2010, 02:59 PM

Ok, I am not sure which 120 I have. I have taken some photos of it. Maybe it will help someone identify which model I have and wether or not I am hooking up the lines properly. First photo is the left side of the engine. So the little screw in the middle of the carb barrel to the right of the high speed needle is the low speed adjustment? The second photo is of the right side of engine, just to maybe help identify which 120 this is. The third photo is the top left of engine. I have included this one to ensure I have the fuel lines connected properly. I have the fuel supply line connected to the top left fitting on the crankcase (the line is connected in this photo), and the top right fitting is what I am connecting to the pressure port on the tank. (no line connected in the photo.) I am running a pressure check valve on the pressure port hose to keep pressure in the tank and a filter on the supply side. I am going to remove the regulator and check for debris. Thanks.

BBW Walt · #4 02-15-2010, 03:30 PM

I have had 2 YS120's and neither had a low speed adjustment. Look on the bottom of the case in the front of the engine right behind the prop driver. There's a brass slotted plug. This is the low speed adjustment or pump pressure adjustment. It should be flush with the aluminum case for starters. Also this engine should be run on 20% nitro and 20% oil. Also synthetic oil s a must as the pump diaphram is silicone and petrolium products will deteriorate this..Start engine and let idle, if it continues to go slower and slower till it blubbers and dies, turn the pump pressure adjustment clockwise slightly while looking at the bottom of the engine. Fire it again and continue till it clears up. After each adjustment, readjust the Hi speed 200 RPM's rich from max and try again. Once the pump is correct you will never have to mess with it again..My experience may differ from others, it works for me over the years

BBW Walt · #5 02-15-2010, 03:35 PM

you can check the pressure check by blowing on it. Air will pass one way and not the other. Side you can towards engine, side you can't goes to the tank side. Nipple on case bottom is a vent drain, run a hose to the outside of the plane off this nipple. Be sure you got a good tank and its correctly sealed. YS's can produce in excess of 5 lbs pressure in the tank

n-doering · #6 02-15-2010, 10:30 PM

BBW Walt, I had a look at my engine, it has the same brass screw your photo has. mine is turned in past flush. Should I back it out to flush and start adjustments from there? Also, there is a screw on the throttle body behind the throttle arm seen in my right hand photo. I believe this is a set screw for the throttle plate stop. (?) Is there a recommended setting for this screw and what exactly is it's purpose?

Mike Gabbard · #7 02-15-2010, 11:55 PM

They're 4 or 5 diff ys120 I know 2 of them have a lowspeed needle the ones i know of that do have a ls needle the needle is where that black philips screw is next to your high speed needle in the first pic. I cant tell if that is one of them or not.
Walts explanation sounds good to me except I would run 30% nitro 24% low viscocity oil heli fuel from wildcat fuel in those ys engines.

BBW Walt · #8 02-16-2010, 06:17 AM

Quote:

Originally Posted by n-doering

BBW Walt, I had a look at my engine, it has the same brass screw your photo has. mine is turned in past flush. Should I back it out to flush and start adjustments from there? Also, there is a screw on the throttle body behind the throttle arm seen in my right hand photo. I believe this is a set screw for the throttle plate stop. (?) Is there a recommended setting for this screw and what exactly is it's purpose?

I would try backing out the pump to the flush position and try from there. Keep count how much you move the pump to know where your at. These YS's are very tempermental with the pump not correctly set. You motor is a "pre" air chamber engine, maybe 1st or second design.

Mike Bargman · #9 02-18-2010, 10:50 PM

This is why Walt is "THE MAN"