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HelicopterCentury Radikal G20-30 N640 Hawk Predator › Smoked an OS .50 - need advice!
03-13-2003 04:47 AM  14 years agoPost 1
rdoupe

rrNovice

Long Beach, CA.

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I just grenaded my .50 OS engine and need an opinion as to what went wrong. Here are the facts...

Equipment

1) Engine = OS .50 SX-H
2) Fuel = PowerMaster YS 20/20
3) Fuel Pump = Perry
4) Heli = Raven 50
5) GV-1 Governor

Action

1) Strapped bird down on table in driveway
2) Started engine, engaged governor (1800 rpm headspeed)
3) Slowly increased pitch up to 8 degrees to load down engine.
4) After a few minutes a loud metallic snap was heard.
5) Engine quit, melted down fan shroud and glow plug socket.
6) I wasn't sure whether to feel stupid or seek warranty on engine.

Summary

I'm new to helis and I wonder if the load I subjected the bird to was too severe, or perhaps the mixture was to lean? Or, maybe the piston locking tool ( used to install clutch )hosed the piston?

Please advise - I'm sorry to ask such a lame question, but I am new to this...


Here's a picture of the piston...


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03-13-2003 04:51 AM  14 years agoPost 2
raptorkid

rrVeteran

Maryland Posts:10000

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Piston Locking Tool

I think that was from the piston locking tool. Most people here use a toothbrush through the carb bacause a piston locking tool puts too much pressure on he piston.

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03-13-2003 04:59 AM  14 years agoPost 3
Twobeers

rrKey Veteran

Toronto, Canada

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You done gone and blowed it all up sir.
Send it in for warranty service and play dumb. Maybe it will work.
Would you hold down your car in one spot and trump on it, hold the speedo at 90mph and not expect something to break sooner then later.

I lost my infamous tag line.

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03-13-2003 05:04 AM  14 years agoPost 4
inventory

rrApprentice

CA

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I'm no expert, but it seems like pulling 8+ degrees pitch at 1800 RPM, you're lucky you didn't rip the landing gear right off.

If I may ask, whats the point of loading it like that anyway?

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03-13-2003 05:17 AM  14 years agoPost 5
vitek

rrKey Veteran

Corvallis, OR

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Whoa, was that your break-in procedure for a new motor?

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03-13-2003 05:28 AM  14 years agoPost 6
jimmyhua

rrVeteran

Guam

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Well, looks like a combination of problems.

Piston locking tool prolly scored the piston. And then you done ran it at max or close to max power off the engine on it's very first run! That piston head looks like you ran it for many many 100s of tanks of gas. But if that's the result of 1 tank of gas, you were a bit aggressive on the needle.

For your first tank of gas. I recommend running the blades at 0 pitch, and then richening up the motor so that it's so stinking rich that it can't turn the blades around too fast. (say like 50 rpms, that's right 50 rpms, that's no typo). Also, don't got beyond 60% throttle. Change your throttle curves so that you can't

After that, lean it out so you just have enough power to hover around.

Disable that governor for the first 5-10 flights, until you get that engine properly broken in, for the first 2 flights, change your throttle curve so you can go beyond 70% throttle. After that, sets yourself a sane throttle curve and take it real easy with the heli (hover around only for the next 5 flights). Then optimize the needles (usually between 1-1.5 turns from fully closed, and idle needle in stock position), and THEN activate the governor and have yourself a blast.

Also, Enya#3 plugs or Enya#4 plugs are good.

I wouldn't use YS20/20 fuel on anything other than a YS (waste of good money). It should be fine for breakin though.

Jimmy

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03-13-2003 05:35 AM  14 years agoPost 7
Safe_Cracker

rrKey Veteran

Chicago, IL

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But...

By him doing that is no different then strappig it to a runup stand.Chances are that was caused by thie piston locking tool or it went lean.This very problem has been happening with the OS 70s also.I do believe you need to break them in good before putting a heavy load on it but as far as OS's opinion they say you don't need a break in period.I have been using runup stands for a while and in the right hands they can be a very useful tool.The idea is load the engine down in a somewhat similar way as in flight to get the engine mixture close to its ideal setting.Strapping it to a bench isn't the best because it is still in ground effect and as for a runup stand, is much better because it is out of ground effect (away from the ground).Slap it back together and play stupid!Goodluck..

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03-13-2003 05:35 AM  14 years agoPost 8
Geo

rrApprentice

Australia

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Rdoupe

You can get a short motor, OS 50 SX from Justengines UK

49Pounds

Try again richer and not bolted down

Geo

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03-13-2003 05:38 AM  14 years agoPost 9
rdoupe

rrNovice

Long Beach, CA.

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The break in the piston does seem to come from the center - where the locking tool rested. I must admit that I thought using the tool might cause trouble, but then I decided to use use it and be really careful to not put too much pressure on the piston. Oh, well - a lesson learned.

I won't try to get warranty on the engine because I'm sure it was my fault and I have already ordered another one that should arrive early next week.

The purpose of loading the engine was to verify proper governor operation and mixture under load. The problem is that I didn't have enough time to do that!

By the way - how do you set mixture on these things? Before this heli, I have always flown airplanes with four strokes and I would use a tach to set the mixture properly. The problem with my heli is that I'm way too afraid to get anywhere near the thing when it's running to make any adjustments. With an airplane, you make sure the prop size /pitch won't allow the engine to overspeed and then wide open the throttle using a tach to reach peak and then back off a bit.

I've never blown an engine before today! I am really careful (at least I thought I was)

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03-13-2003 05:40 AM  14 years agoPost 10
Smokinjo

rrApprentice

Memphis TN

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Send it in to Hobby Services with a letter indicating you bought it and installed it and that was the result. Do not forward any other info (ie..as what you stated in the above post) and they will probably send you a new one if you have a valid receipt where it was purchased here in the USA.

Good Luck

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03-13-2003 05:50 AM  14 years agoPost 11
Gearhead

rrMaster

Vt

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you really burned-up the baby didn't you !! seems everything you did on the table was all wrong, you work that baby to hard without a brake-in, look at all that black on the piston, she got really hot !!

want to sell the carburetor ??!

Jim

Jim
Buzz Buzz Buzz

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03-13-2003 06:29 AM  14 years agoPost 12
rdoupe

rrNovice

Long Beach, CA.

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Hey, I did break the engine in. I ran a little over two gallons of 10 percent through it over a three week period. I never attempted to load it down until after that period (which included a couple of flights) and Ihad the governor set up. I did get quite hot - I could hear the unburned fuel boiling on the inside. Hey - the crank, sleeve, crankcase, head, carb., bearings, and rod are all fine! If it was a lean run, I would think that the brearings would have been damaged, but they're fine - along with everything but the piston. Go figure! I don't want to sell any parts - I'll keep them for spares, but thanks...

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03-13-2003 12:02 PM  14 years agoPost 13
Jim C

rrVeteran

PA

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damn!!! that looks the same way jagboys piston did when it went in his 50.... im nervous now.. i have one and i really dont feel like hearing it shell out... what is up with those pistons.. but yours however looks like it was run pretty lean if that is a brand new motor it shouldnt be that dark that quick.. i have an os 65 la and i have 30 flights on it so far and the top of the piston is still shiny as a mirror.... would it be possible that since the gov hides a poorly tuned motor that it could be the cause of these failures?????? or am i just smokin crack?? if the motor was lean the gov is gonna make it run what you tell it to and therefore something is gonna give if it isnt tuned correctly... right???


jim

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03-13-2003 12:51 PM  14 years agoPost 14
vetrider

rrElite Veteran

Daleville, AL​(Ft.Rucker)

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The piston locking tool and TOO much muscle did this engine in for ya. but it was about to score the piston anyway as it was leaning out from getting TOO hot while being under TOO much load. Also, you do NOT have to run a new engine TOO "slobbering" rich for it to get a good break-in and last a long time. Usually less than 1/4 turn more on the MAIN needle.
The tooth brush trick or a crank locking tool is the safest way to get the fan and nut tight on the crank.
Do NOT tie the heli down and breakin the motor, just fly it around and vary the power regularly. Also land about 4 times for a 10 min tank of fuel and let the heli idle for a min. This will heat cycle the engine which is good also. No prolonged full throttle climbout for a couple of tanks.

Weed thru the BS on here and with a little luck you'll have a great running engine for a LONG time.

Nolan

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03-13-2003 01:19 PM  14 years agoPost 15
woppini

rrApprentice

Dublin CA

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Pistion locking tool? hmm, take a close look. If thats a mark in the piston crown, then it not from that. The mark isnt centered. Maybe some metal dislodge from overheating and got sucked through the port

my wifes cooking is so bad, the flies are sewing the holes in the screen door

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03-13-2003 01:44 PM  14 years agoPost 16
Pete

rrApprentice

Mcdonough, Georgia

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locking tool

just as another way to deal with holding the piston without scoring the thing is to position the piston to just above the ports then feed in soft cord thru the plug hole till the chamber is full then turn the crank till the piston compresses the string/cord and it will evenly hold the piston with no chance of scoring the piston. (use this on an auto engine to keep valves from falling in when removing springs ) You can also remove the head and pack part of a paper towel in the chamber then put the head back on and crank away !

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03-13-2003 02:08 PM  14 years agoPost 17
aeromorris

rrApprentice

Murfreesboro, TN

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rdoupe,
I'd like to congradulate you on your honesty . I think a lot of folks here would just throw the engine in a box and say it was defective. I believe it takes real character to admit that you may have done something wrong. With that said, do a search on proper break-in proceedures for ringed engines on this or one of the airplane forums. In general OS's are fairly forgiving. Hope you have better luck with your next one!
-J

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03-13-2003 03:01 PM  14 years agoPost 18
rdoupe

rrNovice

Long Beach, CA.

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I've always been impressed with OS engines and this one is no different! I think the poor thing held on for dear life and then it just couldn't take it (me) anymore. I did use the piston locking at least three times on that engine because I kept taking the flywheel off for magnet mounting and balancing. The dark piston color is really a "rainbow" color. The area surrounding the hole is depressed - even more so around the exact center.

I did notice that the piston is thin, but then again, these engines do run at a very high rpm and maybe the piston really needs to be that light. My conclusion (based on replies) from this is that OS engines are very tuff and run great and I need to take it easy with them until after the run in. I'll also go down to 15% nitro and keep the needle on the rich side.

Thanks!

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03-13-2003 04:10 PM  14 years agoPost 19
helimike77

rrApprentice

La Habra, CA

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I was always told not to use a govoner until all engine tuning problems are solved. You might want to just make sure everything is set at factory settings. My came shipped to me with only a quater turn out on the main needle when the book says to start with two. I just hovered for a couple tanks and its been runnig great since.

Mike

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03-13-2003 05:48 PM  14 years agoPost 20
rdoupe

rrNovice

Long Beach, CA.

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Hi Alex, what caused your 70 to blow up? Was there any other damage?

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HelicopterCentury Radikal G20-30 N640 Hawk Predator › Smoked an OS .50 - need advice!
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