Go Back  RCU Forums > RC Airplanes > Beginners
Reload this Page >

Rules for 2 stroke engine's break-in

Notices
Beginners Beginners in RC start here for help.

Rules for 2 stroke engine's break-in

Old 03-14-2010, 09:56 PM
  #1  
armody
Thread Starter
My Feedback: (10)
 
armody's Avatar
 
Join Date: Aug 2005
Location: Rockwall TX
Posts: 1,452
Likes: 0
Received 0 Likes on 0 Posts
Default Rules for 2 stroke engine's break-in

Hi ya'll,

I always wanted to find out and ask what exactly are the rules for engine break-in. I have ordered JBA .56 through knoxhobbies, still haven't gotten any shipping confirmation yet but it's scheduled to be delivered this week. How do we break-in the engine?

1. Use the recommended props?
2. How many tanks need to run through?
3. How should we let the engine run? Full throttle, half or quarter and do we have to keep moving throttle full to lower up down over and over again or some time delay?
4. What is high speed and low speed needle and where is it located? is it the one that we turn to make the engine run lean or rich.
5. After succcessful break-in which size prop should be used and mostly engine should be run on rich side or lean side? pros and cons of rich & lean.
6. Last question does break-in apply to all the 2 Stroke engines same way.

Thanks in advance, though I asked a lot of question but I gotta do it for the first time so I want to be sure before I do anything. As I always used pre-broken-in engines or running engines.

Mody
Attached Images  
Old 03-14-2010, 10:16 PM
  #2  
Gray Beard
My Feedback: (-1)
 
Join Date: Apr 2003
Location: Hemderson, NV
Posts: 14,396
Likes: 0
Received 7 Likes on 7 Posts
Default RE: Rules for 2 stroke engine's break-in

When you buy a new engine the break in instructions come with it along with the prop range that the engine can use. They usually have a prop size they recommend for break in then you can start testing any props within the sizes they state. New engine instructions are pretty good about walking you through everything step by step.
Old 03-14-2010, 10:22 PM
  #3  
armody
Thread Starter
My Feedback: (10)
 
armody's Avatar
 
Join Date: Aug 2005
Location: Rockwall TX
Posts: 1,452
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

Thank you GrayBeard,

Follow the instructions, and do not deviate?
Old 03-14-2010, 11:24 PM
  #4  
jimmyjames213
Senior Member
My Feedback: (2)
 
jimmyjames213's Avatar
 
Join Date: Aug 2008
Location: L
Posts: 1,655
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in


ORIGINAL: armody

Thank you GrayBeard,

Follow the instructions, and do not deviate?
heres what to do
put a small prop on the engine, this will keep the load down (aka heat) which can be bad for the engine at first
also used a high pitched prop not a 3d one, this will maxmize the airflow over the engine and help keep it cool
i would use a apc 10x7 for breakin or maybe even a apc 9x8.5
then when you start the engine go to full throttle as soon as possible, keep the engine in a rich two stroke (about half a turn from peak, maybe more) but do not let it 4 stroke EVER,
from their you could fly the engine as long as you keep some throttle on it (usually above half), dont let it idle around all day.
this helps keep the engine hot enough for the liner to expand, minimizing wear, dont worry about landings, you can go to idle due to the fact the engine has been heating up the entire flight, it wont damage with a 30 seconds of idleing.

what i usually do is keep my idle rich, and my high speed just lean enough so the engine can clear the rich idle. then i fly the engine around 3/4 throttle, every few min i drop it back to 1/3 throttle to let the engine cool off a bit (due to the rich idle) then its back up at 3/4

i can go into all the details if you want but im keeping it simple for now.
Old 03-14-2010, 11:25 PM
  #5  
Gray Beard
My Feedback: (-1)
 
Join Date: Apr 2003
Location: Hemderson, NV
Posts: 14,396
Likes: 0
Received 7 Likes on 7 Posts
Default RE: Rules for 2 stroke engine's break-in

That's a pretty good rule. The manufacture has done this once or twice and figured out how they think it should be done. Then they sell one to someone like me and depending on my mood that day I may feel I know better then they do and do it my own way. Problem then becomes when I pissandmoan about what a hunk of junk the engine is I have no one to blame but myself. It's been known to happen.
Old 03-14-2010, 11:47 PM
  #6  
bigedmustafa
My Feedback: (2)
 
bigedmustafa's Avatar
 
Join Date: Jun 2005
Location: Omaha, NE
Posts: 4,109
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

I own a JBA .56. It wasn't particularly hard to break in.

Use an 11x5 or 11x6 2-bladed prop for your first few tanks. Remember that APC props are heavier than most other brands, and they may not be the ideal prop to use for break-in unless you go an extra size lower in diameter or pitch. This will allow the engine to rev up comfortably without overloading it. Once the engine is broken in, you can try a heaver loading prop like 11x7, 12x5, or 12x6. You'll want to use lower nitro fuel (5% to 10%) during the break-in period; you can try 15% nitro after the engine has 3 or 4 tanks through it.

Tune the high speed needle so you can find peek rpms at wide open throttle, then turn it back about 1/2 turn counterclockwise to richen it back up. Run the engine with the high speed needle set to that 1/2 turn rich-of-peek setting on the ground for a tank or two. You don't want to run it very rich, the engine needs to heat up so the piston liner can expand. While running the engine on the ground, if you have ear protection, you can alternate the high speed needle from 1/2 turn rich of peek to 1/4 rich of peek then back to 1/2 turn rich of peek again. You want to alternate the high speed needle every ten to fifteen seconds. This will let the engine heat up properly without getting overly taxed. If you don't have ear protection, just leave the engine at the 1/2 turn rich of peek setting then walk away while it burns through a whole tank of fuel at wide open throttle. The engine will break in more quickly if you alternate the needle as described, but it isn't worth damaging your hearing.

After two tanks of fuel run through it at wide open throttle, you can try to set the low speed needle to provide a reliable idle. You want the rpms at idle to be low enough that your plane won't roll on pavement under it's own power, but not so low that the engine bogs down and dies while it's sitting at idle. To get your low speed needle set properly, use the "pinch" test.

The pinch test involves leaving the engine at idle speed and pinching the line to the carburetor. If your low speed needle is set correctly, the engine will rev up notably for a second or two and then start to sputter and die. If the engine continues to run and run at the same speed after you pinch the carburetor line shut at idle, your low speed needle is too rich. Turn the low speed needle clockwise an eighth of a turn to lean out the low speed needle, then try the pinch test again. If you pinch the carburetor line shut while the engine is idling and the engine dies almost immediately without speeding up a bit first, your low speed needle is too lean. Turn the low speed needle counterclockwise an eighth of a turn to richen the low speed needle, then try the pinch test again. Continue adjusting the low speed needle in small increments until you get the brief rev up then sputtering and dying previously described.

After about three tanks of fuel, you've run the engine for two full tanks at nearly wide open throttle and then adjusted the low speed needle to get a good low rpm reliable idle. You're now ready to fly.

Fly the engine at that 1/2 turn rich of peek setting you originally started breaking it in with. The prop will unload and the engine will turn faster in flight than it does on the ground. Flying at 1/2 turn rich of peek will keep the engine from peeking even after unloading a bit during flight. After flying three or four more tanks in the air like this, you can begin adjusting the high speed needle back toward 1/4 turn rich of peek for more power. The engine will be very well broken in after this and you should only have to make minor adjustments as weather conditions change.

Feel free to ask any additional questions if any part of this ABC break-in procedure seems unclear. This technique will work well for most any ABC engine, I've only specified prop ranges with regard to the JBA .56. Breaking in a ringed engine requires a completely different technique. Do not use the break-in procedure described on a ringed engine.

Good luck and good flying.
Old 03-14-2010, 11:57 PM
  #7  
jimmyjames213
Senior Member
My Feedback: (2)
 
jimmyjames213's Avatar
 
Join Date: Aug 2008
Location: L
Posts: 1,655
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in


ORIGINAL: bigedmustafa

I own a JBA .56. It wasn't particularly hard to break in.

Use an 11x5 or 11x6 2-bladed prop for your first few tanks. Remember that APC props are heavier than most other brands, and they may not be the ideal prop to use for break-in unless you go an extra size lower in diameter or pitch. This will allow the engine to rev up comfortably without overloading it. Once the engine is broken in, you can try a heaver loading prop like 11x7, 12x5, or 12x6. You'll want to use lower nitro fuel (5% to 10%) during the break-in period; you can try 15% nitro after the engine has 3 or 4 tanks through it.

Tune the high speed needle so you can find peek rpms at wide open throttle, then turn it back about 1/2 turn counterclockwise to richen it back up. Run the engine with the high speed needle set to that 1/2 turn rich-of-peek setting on the ground for a tank or two. You don't want to run it very rich, the engine needs to heat up so the piston liner can expand. While running the engine on the ground, if you have ear protection, you can alternate the high speed needle from 1/2 turn rich of peek to 1/4 rich of peek then back to 1/2 turn rich of peek again. You want to alternate the high speed needle every ten to fifteen seconds. This will let the engine heat up properly without getting overly taxed. If you don't have ear protection, just leave the engine at the 1/2 turn rich of peek setting then walk away while it burns through a whole tank of fuel at wide open throttle. The engine will break in more quickly if you alternate the needle as described, but it isn't worth damaging your hearing.

After two tanks of fuel run through it at wide open throttle, you can try to set the low speed needle to provide a reliable idle. You want the rpms at idle to be low enough that your plane won't roll on pavement under it's own power, but not so low that the engine bogs down and dies while it's sitting at idle. To get your low speed needle set properly, use the ''pinch'' test.

The pinch test involves leaving the engine at idle speed and pinching the line to the carburetor. If your low speed needle is set correctly, the engine will rev up notably for a second or two and then start to sputter and die. If the engine continues to run and run at the same speed after you pinch the carburetor line shut at idle, your low speed needle is too rich. Turn the low speed needle clockwise an eighth of a turn to lean out the low speed needle, then try the pinch test again. If you pinch the carburetor line shut while the engine is idling and the engine dies almost immediately without speeding up a bit first, your low speed needle is too lean. Turn the low speed needle counterclockwise an eighth of a turn to richen the low speed needle, then try the pinch test again. Continue adjusting the low speed needle in small increments until you get the brief rev up then sputtering and dying previously described.

After about three tanks of fuel, you've run the engine for two full tanks at nearly wide open throttle and then adjusted the low speed needle to get a good low rpm reliable idle. You're now ready to fly.

Fly the engine at that 1/2 turn rich of peek setting you originally started breaking it in with. The prop will unload and the engine will turn faster in flight than it does on the ground. Flying at 1/2 turn rich of peek will keep the engine from peeking even after unloading a bit during flight. After flying three or four more tanks in the air like this, you can begin adjusting the high speed needle back toward 1/4 turn rich of peek for more power. The engine will be very well broken in after this and you should only have to make minor adjustments as weather conditions change.

Feel free to ask any additional questions if any part of this ABC break-in procedure seems unclear. This technique will work well for most any ABC engine, I've only specified prop ranges with regard to the JBA .56.

Good luck and good flying.

that would work just fine, although i would use a higher pitched prop for more airflow over the engine
the key to remember on a ABC, ABN, ABL engine is to
1 use a smaller prop than normal lessen the load on the engine which minimizes heat
2 use a higher pitched prop to help with airflow
3 dont set the engine to rich (maybe 800-1000 rpm drop max if your useing a tach, 600ish should be plenty), it wont heat up enough to expand the liner causeing the piston/liner to wear a whole lot more than usual, never ever 4 stroke it
4 keep the RPM's up, this will help the liner expand as well

other than that if you follow those rules you really cant screw it up, abc/l/n engines are relitivly easy to breakin, some people like different methods and while one method may be a little better follow those rules and you will never tell a difference
Old 03-15-2010, 12:02 AM
  #8  
bigedmustafa
My Feedback: (2)
 
bigedmustafa's Avatar
 
Join Date: Jun 2005
Location: Omaha, NE
Posts: 4,109
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

I don't disagree with anything that jimmyjames213 has said.
Old 03-15-2010, 04:02 AM
  #9  
Korps
Senior Member
 
Korps's Avatar
 
Join Date: Oct 2008
Location: Wellington, SOUTH AFRICA
Posts: 438
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

Sorry for hi-jacking the thread. Don't want to start another one unnecessary. I need to break in 'n ASP 75 2 stroke...Would a 12x6 prop be fine for this?
Old 03-15-2010, 08:25 AM
  #10  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Likes: 0
Received 8 Likes on 8 Posts
Default RE: Rules for 2 stroke engine's break-in

A 12x6 is a little small. Maybe a 13x6. I run a 14x7 on my 75AX and that's what I broke it in with
Old 03-15-2010, 08:58 AM
  #11  
HighPlains
My Feedback: (1)
 
Join Date: Mar 2003
Location: Over da rainbow, KS
Posts: 5,087
Received 4 Likes on 4 Posts
Default RE: Rules for 2 stroke engine's break-in

also used a high pitched prop not a 3d one, this will maxmize the airflow over the engine and help keep it cool
i would use a apc 10x7 for breakin or maybe even a apc 9x8.5
I don't think this is a good idea. You want good airflow over the engine, and when you use a higher pitch prop you just don't get this.

Why? Because a higher pitched prop has more of the blade stalled when it is not moving through the air. The tips are moving air, but that air is outside where the cylinder is located.

Use an 11x5 or 11x6 2-bladed prop for your first few tanks.
Good advice for the initial run. Light load gives a broad needle range. Depending on what the airplane is, I would fly with 11-7 or 12-5 or 12-6 to start with. Also remember to open up the needle half a turn or more when you put on a bigger prop before starting.
Old 03-15-2010, 09:33 AM
  #12  
downunder
 
downunder's Avatar
 
Join Date: Oct 2002
Location: Adelaide, AUSTRALIA
Posts: 4,527
Likes: 0
Received 1 Like on 1 Post
Default RE: Rules for 2 stroke engine's break-in

There are a couple of myths being perpetuated here but not to worry, they won't really harm the engine.

The first myth is about never running a new ABx so rich it 4 strokes. This doesn't do any damage at all but isn't quite lean enough to start the running in of the piston/liner. Optimal mixture is around where it's just breaking between the 4 and 2 stroking on the first tank or so. A healthy dose of added castor is a good idea though because it's very kind to the rod bushes.

The second myth is prop pitch. A fine pitch (lightly loaded) prop as mentioned by HighPlains cools the engine just as well as a coarse pitch. Because of an extended argument about this some time ago in RCU I carried out an experiment using a 10x8 APC prop and a slightly trimmed ~12x3 3/4 APC (trimmed to give an identical load) and there was no difference whatsoever in head temp. However for running in it's best to use a fairly small prop, the smallest diam/pitch recommended for a particular engine is fine although I go a bit smaller still.
Old 03-15-2010, 11:10 AM
  #13  
Korps
Senior Member
 
Korps's Avatar
 
Join Date: Oct 2008
Location: Wellington, SOUTH AFRICA
Posts: 438
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in


ORIGINAL: MinnFlyer

A 12x6 is a little small. Maybe a 13x6. I run a 14x7 on my 75AX and that's what I broke it in with

Would you then suggest going straight to a 14x7 or first the 13x6 for break in period? The 12x6 even looks to small on that plane. It actually looks odd to be quite honest, it barely extends over the cowls edges. The reason for going 12x6 is because of the recommendation on the ASP "manual" which comes with the engine.
Old 03-15-2010, 11:22 AM
  #14  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Likes: 0
Received 8 Likes on 8 Posts
Default RE: Rules for 2 stroke engine's break-in

It's never a bad idea to use what the MFGR suggests. If it were me, and I didn't HAVE a 12x6, I certainly wouldn't go out and buy one, but since you have it, and they recommend it, go ahead and use it.
Old 03-15-2010, 11:53 AM
  #15  
flyinrog
Senior Member
My Feedback: (1)
 
Join Date: Sep 2002
Location: Burlington, NC
Posts: 7,183
Likes: 0
Received 1 Like on 1 Post
Default RE: Rules for 2 stroke engine's break-in

I would suggest you remove the cowl, if your breaking in an engine....heat is good in small doses,,,even if you break it in in the air,,remove the cowl....the problem with 4 stroking an engine, is that it raises compression and cools the engine down and just puts more work on brand new surfaces...I have several Norvels, wierdest breakin ever,,soak the engine liner in motor oil for 24 hours, before you crank it up...but after about the 3rd tank, you can actually hear that engine come to life in the air, its like flippin a switch, anyone who's heard it knows......ooop there it is!!....she's broke in now....a week ago I cobbled together a cox .049 out of several engines and if fired up and ran good, third tank, it locked up tight,,but cooled down and still runs fine and I use extra castor in all my engines....just some ramblings....Rog
Old 03-15-2010, 12:00 PM
  #16  
armody
Thread Starter
My Feedback: (10)
 
armody's Avatar
 
Join Date: Aug 2005
Location: Rockwall TX
Posts: 1,452
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

It's ok, you have not stolen the thread, but you used it for free which in this economy I can't afford, pay $49.99 asap, then you can post as much as you want lol

Just kidding

Everybody has a right to ask questions on top of thread, and I do that too.

Guys Thank ya'll for great advices. I'm gonna follow those.

Mody

Happy flying
Old 03-31-2010, 08:59 AM
  #17  
kristj179
Senior Member
 
Join Date: Apr 2009
Location: bear, DE
Posts: 101
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

hello fellas
i have a question about my o.s 40 la engine. the question is this, is this a abc,or a abn engine? is their a way to tell by looking at the piston on the exaust side of the engine? thank for your help
Old 03-31-2010, 09:46 AM
  #18  
RCKen
RCU Forum Manager/Admin
My Feedback: (9)
 
RCKen's Avatar
 
Join Date: Jul 2002
Location: Lawton, OK
Posts: 27,759
Likes: 0
Received 27 Likes on 24 Posts
Default RE: Rules for 2 stroke engine's break-in

The OS 40 LA is an ABN engine.

Ken
Old 03-31-2010, 10:36 AM
  #19  
armody
Thread Starter
My Feedback: (10)
 
armody's Avatar
 
Join Date: Aug 2005
Location: Rockwall TX
Posts: 1,452
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

Today I'm getting my Magnum XLS .46 2 Stroke engine which I need to break in and I'm gonna follow the manual that comes along with 10% Nitro fuel I have. Recommended Prop is 10X6. Can I use 11X6 APC prop, or should I go and get a 10X6 prop Master Airscrew or wooden prop for break in?

Also I wanna know what exactly the engine's position should be on the mount, how far does the crankshaft have to stick out from the sidewalls of the plane. I'm going to install this engine on my Escapade.

Thanks

Mody
Old 03-31-2010, 10:58 AM
  #20  
gunneredwards
Senior Member
My Feedback: (4)
 
Join Date: Mar 2009
Location: Austin, TX
Posts: 291
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

If the break-in calls for a 10x6 then that is what i would use. After break-in, an 11 will probably be ok. The only drawback might be a delay in the engine winding up. As far as mounting location, I would leave a minimum of 3/16" from the rear of the prop to the sides of the body. You will probably have some thrust angle, if it is built into the firewall like most, just measure on the short side. Balance will also affect some of the measurements here, you should have about 3/8 to 1/2 inch of adjustment to aid in balancing.
Old 03-31-2010, 11:36 AM
  #21  
armody
Thread Starter
My Feedback: (10)
 
armody's Avatar
 
Join Date: Aug 2005
Location: Rockwall TX
Posts: 1,452
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

I'd go for the recommended prop 10X6 prolly MA and 3/16" means 16th of an inch? Is that the distance from firewal or what. I'm sorry I did not exactly get it.

Thanks

Mody
Old 03-31-2010, 04:10 PM
  #22  
j.duncker
My Feedback: (2)
 
j.duncker's Avatar
 
Join Date: Jun 2004
Location: Sailing in the Eastern Caribbean
Posts: 4,047
Likes: 0
Received 1 Like on 1 Post
Default RE: Rules for 2 stroke engine's break-in


ORIGINAL: armody

6. Last question does break-in apply to all the 2 Stroke engines same way.
Nope

Engines come with piston/liners of 3 basic types SEE [link=http://www.mecoa.com/faq/abc/abc.htm]CLICKY[/link]

An ABC or ABN or AAC Engine needs to be at normal operating temp ASAP

A ringed piston engine can get by with cooler operating tempretures but needs the ring to get bedded in over a period of time..

A lapped cast iron piston running in a steel liner needs a longer period of running in then either of the above.

Please note that running in practices often result in very heated arguments amongst modellers. There are some long threads on RCU about this. A search should give you an evenings entertainment.

Do note though that ONE LEAN RUN resulting in a higher operating temp can ruin a piston and liner. Get your local engine guru to alert you to the sound of a lean run and a "sagging" engine on its way to an early grave.

Old 03-31-2010, 04:23 PM
  #23  
armody
Thread Starter
My Feedback: (10)
 
armody's Avatar
 
Join Date: Aug 2005
Location: Rockwall TX
Posts: 1,452
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

Thank you,

It's very informative.
Old 04-04-2010, 01:48 PM
  #24  
chashint
Senior Member
 
Join Date: Dec 2001
Location: Rowlett, TX
Posts: 1,309
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rules for 2 stroke engine's break-in

I am another that thinks following the manufacturer's instructions is a good idea.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.