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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › "dimple" on YS 50ST Piston?
08-12-2010 12:26 AM  8 years agoPost 21
airdodger

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Johnston USA

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The one at Ron's is number jrp970106 it has the screw threads on the fitting. They sell just the fitting too, the advantage is you can tighten the fitting and that causes the grommet to seal tight.

Chris

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08-15-2010 01:13 AM  8 years agoPost 22
dchekas

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Farmington, CT

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I'm still waiting for my new fuel tank.

In either case, I'm leaning towards this being the problem.

I took part of the carb apart, everything looks clean. I put fresh fuel tubing and a new plug on the exhaust port of the MP5.

I was going to reassemble the fuel system and test it, but the rubber stopper is very loose when I put it in. So much so, that I can't tighten the nut that holds it in place... The whole stopper just spins. I guess I'll find out when I get my new rubber stoppers sometime next week (Hopefully).

Thanks for all the help!

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-20-2010 12:47 AM  7 years agoPost 23
dchekas

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Farmington, CT

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Okay, I tried it out today.

Brand new tank/clunk line the whole sha-bang.

Same problem persists. I definitely get a "whooosh" when I take the plug out of the vent line, although it is not quite as much as my other YS50ST produces.

I swapped back to the old style carb, and it almost sounded like it was running better, but I was only able to idle it.... since I realized I was out of fuel, and then my starter battery died.

I won't be able to do more extensive testing with the older carb until tomorrow, but perhaps there is something wrong with this new style carb. I haven't taken it apart yet, but the two phillips head screws that hold the side plate on are very tight, and feel like the heads are stripping if I try to loosen them.

I originally swapped them because it seemed like my engine was always hotter then I'd expect when it ran good, but way too sluggish and would die if I richened it to where it was cooler.

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-20-2010 12:56 AM  7 years agoPost 24
airdodger

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Johnston USA

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You need to pressure test the fuel system!

Chris

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08-20-2010 01:30 AM  7 years agoPost 25
dchekas

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Farmington, CT

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Prime it as if I was going to start it, and check for leaks? I will check that tomorrow as well.

Thanks!

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-20-2010 01:36 AM  7 years agoPost 26
airdodger

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Johnston USA

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Get some kind of pump and put around 8 pounds of air pressure in the system and hold that pressure, squirt soapy water around all fittings and see if bubbles happen. The tank is usually the problem if you have it out you can just put underwater and check. Myself I use a pop off gauge for carbs and see if the system holds pressure for unlimited time without dropping.

Chris

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08-20-2010 02:27 AM  7 years agoPost 27
TMoore

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Cookeville, TN

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A vac pump for brakes works like a champ.

TM

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Drones = EVIL

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08-20-2010 09:12 PM  7 years agoPost 28
dchekas

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Farmington, CT

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I should be able to hook up a good air supply to it on Monday and do that type of test at work.

I tried it again today, I used some of the Foam hand wash soap and went around to every fitting. I started the engine and let it idle, although it was a pain to get started. Fuel is dribbling out of the muffler while I have it idling (Low speed needle is set around 7/8s of a turn out). I checked every single fuel fitting: The tank stopper, vent line, both Ts, the plugs, the bottom plate, the one way valve, everything. I didn't see any bubbles or signs of leakage.

I got very weak to no vent pressure when I vented the line... So I'm definitely in agreement that the problem is there is no pressure for some reason... But if I have it running, the engine should be creating pressure, and I should see it leaking out somewhere?

I've replaced the entire fuel tank assembly and all the fuel lines. I could try swapping check valves I suppose, but disassembly shows it being clear, and it is relatively new (~2 months old). I haven't changed my T fitting or my Fuel filter T, but those both are clear as well.

I'm stumped.... Could it be that the piston ring isn't sealing against the sleeve well and is not creating enough back pressure?

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-20-2010 10:50 PM  7 years agoPost 29
airdodger

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Johnston USA

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The higher the rpm the more pressure is produced to a point. You really don't need any pressure for the engine to idle.

Chris

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08-21-2010 12:38 AM  7 years agoPost 30
dchekas

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Farmington, CT

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So at idle, little to no pressure is generated by the engine?

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-24-2010 01:22 AM  7 years agoPost 31
dchekas

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Farmington, CT

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Well, I hooked it up today at work to our air test stand. I pressurized it with 8 PSI.

I checked every fitting again, using our leak detector solution. I couldn't find anything. I put my ear up to the engine and thought I heard a small leak. I check around it and couldn't find anything. I depressurized it and repressurized it and the sound was gone.

I had to stop after that, but I guess I still can't conclude anything. I would like to try it one more time and see if I can't get it to leak again tomorrow.

I'm all but 100% sure the leak is not in any of my fuel lines, fuel tank or carb inlet.

I'll try checking maybe around the carburetor and the head of the engine.

I thought maybe the glow plug was loose, but upon checking it for tightness, it was tight for sure (And the ring is in place!)

I'll report back what I find tomorrow, thanks again.

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-24-2010 01:27 AM  7 years agoPost 32
airdodger

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Johnston USA

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It would be worth checking the tank under pressure and moving the line connection..

Chris

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08-25-2010 04:12 AM  7 years agoPost 33
dchekas

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Farmington, CT

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Got to play with it some more today, and noticed a small leak from the pressure fitting on the fuel tank!

Now were getting somewhere... maybe.

On the previous tank, I had used some thin CA on the pressure fitting to "seal it". But when I swapped over to this tank, I just threaded it in place.

Perhaps:

-The CA in the previous tank didn't quite seal that well, causing the initial problem

-I'm continuing to see it due to another leak.

The leak is pretty small, but I will epoxy in the fitting and give it another go, fingers crossed.

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-26-2010 02:09 AM  7 years agoPost 34
dchekas

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Farmington, CT

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I tried it again today it seemed to be running better.

Unfortunately, I put my Knight 3D in pretty good when the RX battery came unplugged.

The resulting crash took out several of the cylinder head fins. Fortunately, the inside of the engine looks okay.

Nevertheless, I'm leaning towards dumping the motor and replacing it with another. Anyone want a YS50ST?

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-26-2010 02:22 AM  7 years agoPost 35
airdodger

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Johnston USA

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I would think someone here on RR has a cylinder head.

Chris

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08-26-2010 03:04 AM  7 years agoPost 36
dchekas

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Farmington, CT

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Not a bad idea either, they appear to be less expensive then I first thought. Unfortunately, it appears all the big dealers I looked at are out of stock.

Thanks for your help airdodger

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-26-2010 03:28 AM  7 years agoPost 37
airdodger

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Johnston USA

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Try a personal add asking if anyone wants to sell one. Everybody here will help as much as possible, you are welcome.

Chris

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08-28-2010 01:05 AM  7 years agoPost 38
cutter

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Greensboro,N.C.

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Does it matter which side of the connecting rod goes against the crank? I can't tell the difference between the 2 sides, except that one side looks kind of scratched up,like maybe it should go against the crank..I should have marked it I'm rebuilding a ys .61..Thanks

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08-28-2010 01:36 AM  7 years agoPost 39
dchekas

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Farmington, CT

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I wound up sending my YS50 in to be checked out. Hopefully I'll get it back from YS Parts and Service soon.

I also sent my GY601 in for an inspection as well.

Perhaps it was better that my Knight went in as hard as it did (Both frames broke in the crash), it gives me a chance to rebuild it fresh and inspect everything.

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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08-28-2010 03:48 AM  7 years agoPost 40
airdodger

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Johnston USA

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Cutter, yes it matters which side of the rod faces crank. Look at the bottom of the rod, the side that has a radius on the bushing goes to the crank face.

Chris

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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › "dimple" on YS 50ST Piston?
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