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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › YS 120 seems to be running lean after rebuild??
07-30-2012 02:55 PM  9 years ago
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blucido

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Plano,Texas

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YS 120 seems to be running lean after rebuild??
Have flown YS120 since Jan ,aprox 40 gal through her no prob,so decided to put new bearings and ring in just because.Next time aint broke don't fix?? To my supprise the piston was as clean as a new one only some rust on the large crank bearing. Been running Rotor Rage 15 % and tuned to the 'T" like Robert Ables suggested. Now that it's back togather it's pinging no matter what settings I try,I did notice small bubbles in the clear line going from the pump to the carb,Don't think this is normal!I have taken it apart twice and checked gaskets ,put new fuel line on ,checked tank for leaks,not sure if these small air bubbles are the problem,anybody got any suggestions.
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07-30-2012 06:02 PM  9 years ago
knightofcarnage

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chicago

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The airbubbles in the clear tubing. I been battling it for a while. Vibration,foaming fuel and small air leaks in tubing cause it. Now I have 2 good solutions. The air bubbles seam to lean out the low side mostly, at least what i noticed.

1) Bit the bullet and use a ugly header tank (On 700N it will trow your cgy off).

2) (what i did) Fuel bladder, but a with a fuel bladder there some fun things watch out for too. Now the fuel is under so much pressures (after i fixed the 700N tank, its about 9.5 psi + contraction of the ballon,BTW the fix is very easy, just use an extra ballon for the second cork. Its just enough off a thickness to stop all air leaks around the cork.) going in the carb it cause the clear tubing to leak ( the clear tubing is very very soft). I had to replace all my tubing including the clear tubing and use hose clamps. everwhere. Now its happy.
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07-30-2012 08:33 PM  9 years ago
airdodger

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Johnston USA

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That is the way the piston should look,(as good a new one), if it is tuned correct. Pinging is usually not enough pressure might have a leak. I have seen posted by guys that checked the pressure it can be around 9.5 psi, did you use that much pressure? Did you use a new headgasket? The new ring might not be seating in the old liner this will haunt you if that happens to be the problem. It may or may not seat, you can put the old ring back in and retry if you still have it. You will need to know which side was up on the ring too so it goes back in the same place.

You reassembled correctly with the chamfer on the bottom of the rod to the crank face, the bearing fully seated. You used new fuel and a new plug to eliminate those as problems right? You were so right if it's not broken don't go looking for trouble. As stated any pressure leak will not be good. If you let the tank grommet dry out sometimes they don't reseal or it takes a while.
Chris
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07-30-2012 09:22 PM  9 years ago
blucido

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Plano,Texas

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thank you for your reply,you may be on to somthing about not enough pressure! It seems like when i pull the plug to let off the pressure on the tank it is 1/2 of what it use to be? I need to try and figure this out, Thanks.I'll try and let everyone know what develops.
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07-30-2012 09:57 PM  9 years ago
airdodger

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The ring can also be a cause of reduced pressure, keep that in mind. When I was using the YS 140's the reduced pressure caused a slower ramp up that is when I knew the ring was shot.Chris
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07-30-2012 10:13 PM  9 years ago
knightofcarnage

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chicago

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Here a good way to test pressure in your tank.

Get a 50cc syringe or bigger and pressure gauge for bikes etc.
1) Install the pressure gauge normal where you plug your pressure hose( on the 3 way line split)
2) plug your fuel line right where it plugs into the engine (you want to test the entire fuel line including the filters).
3) Now use the syringe to put pressure in your tank tru your 1 way vale. I have a 50cc syringe it takes about 4 full syringe of air to crate around 9 psi in 700N tank. (This also is a good way of test the 1 way valve) . Remove the syinge and your 1 way vale should not allow any air to escape.

I let it sit for about an hour and i see if there is any reading changes. There should not be.
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07-31-2012 02:59 PM  9 years ago
blucido

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Plano,Texas

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Does anyone have a line on a pressure guage small enough to measure the pressure comming out of the crankcase nipple on these rc engines. I'll also check the compression , there are compression guages on the market.
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07-31-2012 05:37 PM  9 years ago
airdodger

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Johnston USA

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This is what I use.

It is a pop off gauge for carbs.
Chris
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07-31-2012 09:32 PM  9 years ago
knightofcarnage

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chicago

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I will find out from my buddy , his screws in to the glow plug spot to measure compression.
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07-31-2012 10:39 PM  9 years ago
blucido

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Plano,Texas

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ya thats a compression guage,it measures cylinder combustion pressure, which is important and has some bearing on crankcase pressure,but i need a low volume air pressure guage which I think I've located at GRANGER'S for $11 ,much like the Carb pop off guage pictured above.
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08-03-2012 11:22 PM  9 years ago
ticedoff8

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Morgan Hill, CA. USA

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Air bubbles in the clear line between the regulator & the carb:

I have a YS 91SR-3DS and I noticed the same thing the other day. It is either the first time I noticed it, or its been happening for awhile and I didn't see it.

I was going to post my own thread on it, but I noticed this one.

Since I already run a header tank and I don't really want to add a bladder, is there a 3rd option?

One of these responses here seemed to suggest running higher pressure in the tank - How would that help?

I just assumed it was a pin-hole - but I pressurized the system with my mini air compressor (I use it for vacuum bagging wings too) to about 9psi and I couldn't find a leak.

I guess I really don't know what psi I am actually running in normal flight, but the 1-way check valve seems good - lots of "whoosh" as I uncork the vent after a flight.

I checked the regulator diaphragm and it looks okay and there is no "leak-down" of fuel into the carb while the system is pressurized and the engine is stopped.
+ > ÷
Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!
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08-06-2012 01:47 PM  9 years ago
blucido

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Plano,Texas

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still having pining issues,have tried all new fuel line in tank and outside ,even on carb regulator,taken motor completley apart and cleaned carb and needles,has new ring and bearings in engine,tried with and with out check valve,this motor use to purr like a kitten and run great, haven't tried a blatter or side tank ,it ran perfect before the rebuild,and my other one runs perfect without a side tank or bladder?? gonna contact Rich at YS and see what he says.
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08-06-2012 03:32 PM  9 years ago
knightofcarnage

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chicago

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Go with the bladder. It easy to make and it works. Gets rid of the pinging.
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08-13-2012 02:54 AM  9 years ago
haha

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Woodstock,GA

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sget rid of that motor, i went through TWO YS 120z and blew both of them in the process of tuning. People will say i dont how to tune but i had a 91SR-3DS and i got that thing tuned so well that my friend, who had a 91HZ-R, had to upgrade to OS 105 to keep up in term of power. I agree the 91SR-3DS and the YS 120 are two different engine but i have no idea how they can be that much of different in term of tuning. Having said that, I recently switched to an OS105HZ-R and ALL I CAN SAY IS "WOWWWWWWWWWW". Easy to tune and power output is crazy.
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08-13-2012 02:18 PM  9 years ago
blucido

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Plano,Texas

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well I'm gonna send it back to YS and see if Rich has anything for it,I've tried new fuel line in and out of the tank, a header tank,a fuel magnet,different plug,checked my vbar gov. settings,taken the motor completly apart twice,checked the fuel regulator gaskets,& diaphram,taken carb apart,we'll see , I have another one and it runs great like this one did before I put a ring and bearings in it,mayby somthing I messed up???
It only seems to run lean at idle/hover and comming off Idle 2 and landing , I know I don't fly in this mode but it should not ping so bad.I'll keep you guys posted ,don't want to give up on this motor but am considering a 105 just to see the difference.
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09-20-2012 08:40 PM  9 years ago
blucido

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Plano,Texas

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ys120
well told you guys i would report back, after sending the 120 to Rich at YS he tore it down & said he could not find anything wrong and ran it on his test bench??? he then sent it back to me, no charge! I put it back in my Rave #2,to my supprise it started up rather quickly and on two 1/4 tank test hovers in my back yard it's runnning like the old days,PERFECT,I had to richen the idle needle to about 3/4 but so far so good? he must have
tweeked something but what I don't know. I'm gonna put her to the test this weekend at the Southern Rotary Classic ,keeping my fingers crossed . wish I had more to report to help those having issues ,but so far both my 120's are good.
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09-21-2012 12:53 AM  9 years ago
helipulse

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Toronto, ON, CANADA

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I have been flying my whiplash with YS120 and using OS91SZ-R carb on it and it files awesome. Has Insane Power. I am using the 15% masters blend, Hatori pipe, OS 8 plug and this thing idles for ever.

Using oS 10 plug, Enya 5 plug I think is all BS. YS needs to fix their carb.

The YS carbs are a problem, The OS carbs are awesome. Use them together and you have one awesome combo.

Will post some pics soon.
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09-21-2012 12:53 PM  9 years ago
Kyle Owen

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Florida

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You did what???? ^^^^sponsored by overtime
Formerly known as MADROTORZ
THANK A VETERAN, PUNCH A POLITICIAN
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09-21-2012 01:34 PM  9 years ago
GScott

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Lewis Center, OH

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Buzz at Magnum Fuels has an adaptor for the 120 that allows OS carbs to be used. He is also working on one for the YS60.
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09-21-2012 02:59 PM  9 years ago
Kyle Owen

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Florida

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Im going to have to check that outsponsored by overtime
Formerly known as MADROTORZ
THANK A VETERAN, PUNCH A POLITICIAN
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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › YS 120 seems to be running lean after rebuild??
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