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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › help with lean running hyper 50
09-21-2009 01:54 AM  11 years ago
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busyflyin

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Cadillac, MI USA

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help with lean running hyper 50
I blew a hole in the top of the piston due to a hole in the clunk line of the header tank and the engine leaned out in flight. I replaced all fuel line, piston and ring, and honed the sleeve. The engine is now very hot even with needle out 3.5 turns. Back plate is too hot to keep my hand on it, but the motor is blowing smoke. however, it doesn't seem to be running very rich. I'm thinking that I should just replace all of the "o" rings in the carb in the event I smoked those too. What do you think?
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09-21-2009 02:18 AM  11 years ago
Jafa

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Sydney, Australia

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Also replace the back plate gasket and ensure it mates well

Check the exhaust pressure is not being lost

Strip the carb down and blast it clean with compressed air and brake/carb cleaner
Then replace o rings just in case

Check head gasket and ensure head bolts are tight

It's a bit of a pain but you've got to resolve it

Protos | Logo 400 & 500 | Sceadu Evo | Freya Evo | Trex600N | Avant FX
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09-21-2009 02:58 AM  11 years ago
bigwolf1

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USA

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sounds like you sucking air from some were. Jafa hit it. take it back down and ck every thing. I missed getting the head down on one and it burnt it up.MAH blade Rep
Trex700LE
Magnum fuels
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09-21-2009 11:11 PM  11 years ago
busyflyin

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Cadillac, MI USA

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I ordered all new O rings and gaskets today from RCheliworks. I'll replace everything and see how it does. Thanks!
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09-22-2009 12:44 AM  11 years ago
BarracudaHockey

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Jacksonville FL

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While its possible those are the causes, when you hear hoof beats think horses not zebras. Check the fuel system, including the clunk line, pressure check the tank and replace all the lines.Andy
AMA 77227
http://www.jaxrc.com
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09-22-2009 12:56 AM  11 years ago
busyflyin

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BH: done that... still lean. Thanks!
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09-22-2009 02:37 AM  11 years ago
airdodger

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Johnston USA

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You may have ruined the piston to liner fit with the honing. The honing may have been too coarse or too smooth, or the crosshatch incorrect. It's very easy to taper a liner or bellmouth it at the top where the fit is most important. Honing is one of the most important things in an engine. You might have ok results if you just break a glaze, but if the engine needs anything more then that it is probably best to replace the liner too. What did you set the ring end gap at? What grit stone? Get the needle settings close and try again. Too much fuel can cause the engine to run too hot also, excess oil can generate a lot of heat trying to compress it.Chris
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09-22-2009 03:07 AM  11 years ago
busyflyin

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Ring end gap? Grit stone? Who does that?
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09-23-2009 01:57 AM  11 years ago
dkshema

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Cedar Rapids, IA

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The motor originally died from a lean flight. You fixed the motor, it's still running lean. Look for those horses that Barracuda mentioned.

After making sure you don't have air leaks in the plumbing, that the muffler is tight, and you don't have a leak in your tank, remove the needle valve from your motor, open the throttle barrel, hook a length of fuel line to the carb input nipple, and blow and suck on the hose a couple of times. Cover the hole where the needle valve came out of with your finger. If you have anything in the needle valve spray bar, this will usually pop it out and you can easily tell when it's gone.

Make sure your carb body is firmly seated on the crankcase, and that the rubber O-ring is intact at the carb's base.

If you used a brake cylinder hone, you didn't kill the sleeve. You would really have to grind away to kill it, after all the stones are nearly the length of the cylinder. Very difficult to get a weird taper at either end.

If it's lean, you have an air leak somewhere either in the fuel system or motor assembly itself, or the tank vent line is plugged somewhere along the way.
-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz
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09-23-2009 02:58 AM  11 years ago
airdodger

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Johnston USA

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dkshema [quote]If you used a brake cylinder hone, you didn't kill the sleeve. You would really have to grind away to kill it, after all the stones are nearly the length of the cylinder. Very difficult to get a weird taper at either end. end [quote]
I am going to assume that you are moving the stones to get a crosshatch, just dwell a little too long at the top of the liner you will have a bellmouth, the worst place to take material away. There are a lot of drawbacks to doing anything but breaking the glaze. There can be hard spots in the liner, you don't have enough pressure on a break hone to overcome these. The ring is made to seat using a specific grit stone and a specific crosshatch and the proper honing fluid. Unless you have a bore gauge you have no way to check if you damaged the cylinder. As the ring seal is the most important piece in the engine to produce power everything has to be correct to achieve max power. It's just my opinion if you really need to hone the cylinder I would replace the liner.
Chris
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09-23-2009 04:27 AM  11 years ago
dkshema

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Cedar Rapids, IA

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Nice theory, but the proof of the pudding is in the eating. I've honed a few cylinders in my lifetime, haven't used exotic tools, and saved quite a few bucks in the process. Clarence Lee, when he wrote the "Engine Clinic" column for RC Modeler taught me a lot.

Imagine this -- a finger, some 280/320 grit emery cloth, and some elbow grease. Or you can go the hone route as noted in the link below.

http://www.mecoa.com/faq/piston/scored/scored.htm

or perhaps those silly folk at MECOA have just gone plain nuts. What could THEY know about these motors?

I think Terry Moore here on RR prefers the emery cloth/finger or wood dowel route, if I remember correctly. Not very scientific, not very pretty, but then it is a technique that simply works.

http://www.runryder.com/p2098810/

Sometimes he uses a deep-well socket, too

http://www.runryder.com/p3252818/

Terry's one of those old geezers like me, only he knows his way around CNC machine tools and metallurgy a lot better than I.

It would seem that these little two stroke engines really aren't magic after all. Common sense with simple tools goes a long way.

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-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz
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09-23-2009 04:54 AM  11 years ago
Santiago P

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Dayton

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busyflyin

I also agree with the BH and dkshema. Something must be wrong in the fuel system. Take a small needle or drill and poke the pressure tap on the muffler, make sure is not clogged. If you haven taken the carburetor apart, remove the high speed needle and power flushed the carb with a syringe of fuel pump to blow any particles caught in the orifices.

Also carburetors have gunk build overtime, normally when left sitting for a while with fuel on the lines. Check for anything at this point.

If you have access to a carburator from another OS50, try it to see if it helps anything.

Good luck

Santiago
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09-23-2009 11:32 PM  11 years ago
airdodger

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Johnston USA

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dkshema So the manufactures go through extensive testing, engineering, machining, and we spend many dollars on exhaust systems to get the last bit of power we can extract from the engine, then we go hone the cylinder with sandpaper, I must be missing something. I have had conservations with Lee about getting more power out of these engines, his answer was he would not even try to get more power out of the engine with the amount of engineering they do on the engines. I said breaking the glaze is not a problem I have used emery paper and oil numerous times and had ok results. I have owned many Lee engines none were honed with emery paper. I have also been around longer than you and that gets me? The point is that many on here have some knowledge on engines and some have limited experience and wouldn't know not to use a hundred grit stone, others would use any hone they happen to have that can lead to problems. Meoca has some questionable info on their site for sure. I guess that OS could just hone the liners with a socket and you would be happy, I would not, even if the engine ran ok I would still be bothered that it was not done as good as could be. Depends on if you are looking for as good as can be or just ok. I tried many things to get the computer to work correct I can't even make a second reply to a post. lol I guess I am a lot more interested in the engines running correct than the computer, I must be using the wrong grit on the board.Chris
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09-24-2009 12:05 AM  11 years ago
labont

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sudbury, ont, canada

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Honing is just to create microscopic scratches to hold oil and allow the ring to seat. You're only supposed to hone long enough to create these scratches then stop. It doesn't take much. You're not even removing cylinder material... you are only raising/lowering the surface with them. Honing is not intended to fix any cylinder issues other than a place for the oil to sit and help seat the ring. Considering they are only superficial microscopic scratches I can't see any reason a finger and some 280 grit sand paper can't do the trick. If honing did more than this, like helped round a cylinder, the obviously a finger can't do it.

I've seen crosshatching still visible on some of the two-stroke engines I have been in over the years still visible after a couple thousand miles. And that is a good sign, not a bad one like some people think. The longer they last the longer the thin film of oil can exist to keep your ring and piston skirt healthy.

But again, they are just superficial abrasions. I would not worry too much about how they get there, as long as they are there. All my humble opinion of course. I love discussing engines
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09-24-2009 01:11 AM  11 years ago
busyflyin

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Cadillac, MI USA

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Boys.. boys... not that big of a deal (kinda fun when people get cranked up on an issue). I honed it with a brake hone. I mostly know what I'm doing.. good cross hatch, and I used plenty of oil. The hone hardly touched that hard material. I haven't had a chance to tear the engine down again cause I'm waiting for all of the o rings and gaskets I ordered. I'm pretty confident that the problem is either a leaking head/carb, or some other fuel related prob. The muffler tap to the tank is clean.. at least I can easily blow air through it. Thanks for all of the input to the solution and I'll use most of it to help resolve the issue.
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09-25-2009 11:04 PM  11 years ago
busyflyin

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Cadillac, MI USA

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I've replaced all o rings, head gasket and backplate gasket. I have the needle 3.5 turns out and it smokes like my ol gramma used to. But, it's still hot at the back plate. It's also running rough like rich so I know it's not sucking air. What now? Run it til it's broke in?
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09-26-2009 12:35 AM  11 years ago
BarracudaHockey

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Jacksonville FL

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Is the backplate scatched up like the crank pin is rubbing?Andy
AMA 77227
http://www.jaxrc.com
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09-26-2009 12:49 AM  11 years ago
busyflyin

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Hmm.. have ta look. I'll take a look in the morning.. good thought.
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09-26-2009 02:41 AM  11 years ago
airdodger

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Johnston USA

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09-26-2009 02:15 PM  11 years ago
busyflyin

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Cadillac, MI USA

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Here's a few pics of the back plate. It's scratched, but I'm not sure how bad it is.. take a look

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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › help with lean running hyper 50
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