Go Back  RCU Forums > RC Airplanes > Beginners
 How to break-in engine >

How to break-in engine

Notices
Beginners Beginners in RC start here for help.

How to break-in engine

Old 03-06-2008, 12:24 PM
  #1  
Thread Starter
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default How to break-in engine

I'm wondering what people's methods are, mainly for securing the airplane, for engine break-in.

I'm going to be taking this thing for the first time, most likely alone, to a field just to burn a couple of tanks of gas and break-in the engine (following manual's directions).

What to you suggest for holding the plane down?

Any other tips?

Thanks.
Old 03-06-2008, 12:31 PM
  #2  
 
bingo field's Avatar
 
Join Date: May 2004
Location: Mt. Morris, NY
Posts: 1,732
Received 3 Likes on 3 Posts
Default RE: How to break-in engine

I use a tent stake nail with about 5' of cotton rope in a loop around the tail. Some people use a screwdriver to hold the rope. There are some manufactured devices available at most hobby shops that have a vertically oriented, cushioned U shaped bracket to hold the tail. The advantage to those is that it makes it nearly impossible to "accidentally" get the model to move, where as the rope version will allow the model to move forward if the rope had any slack in it when you fire up the engine. Either way, please be very careful with the prop area, and don't be too disappointed if the engine doesn't start with the first couple of flips. If new, they may take a couple of minutes to get started the first time. After you get them started a few times, and needles tuned, they usually start quite easily. Good Luck!
Old 03-06-2008, 12:45 PM
  #3  
 
bingo field's Avatar
 
Join Date: May 2004
Location: Mt. Morris, NY
Posts: 1,732
Received 3 Likes on 3 Posts
Default RE: How to break-in engine

I usually leave the needles where they were from the factory before I try to start for the first time. IF I can't get to start after about 10 min. of trying, I use this procedure on the engine. I have used this on engines that people have brought to me that won't run, and have managed to get almost all of them working well it, also:

Patience is the key, and make only small adjustments, one at a time!

PS: I didn't write it, and thank whoever did for it, it has been valuable to me.


How to setup the needles so you can get your engine started.

Remember the following rules about needles:

1. Low end needle affects the mixture below 1/2 throttle for most engines. Use it to adjust the idle and the transition from idle to full throtttle.
2. High end needle affects mixture above 1/2 throttle. Adjust it so engine is running 300-400 rpm shy of max lean rpm at wide open throttle.


Start by opening the high end needle about 4 turns from fully closed. This is just a starting point to ensure the high end needle valve isn't restricting fuel to the carb so you can adjust the low end needle setting.

The low end is easily set to a good starting point with the following procedure:

Close low end needle valve completely.

Install a clean piece of fuel tubing into carb fitting, make sure it is long enough for you to blow into it with your mouth.

Open carb to 1/5 open from closed position

Blow into fuel tubing while slowly opening up the low end needle valve. Stop turning low needle valve when you first feel air blowing into carb from your mouth or hear the sound of air blowing into carb. The flow should be restrictive and very small. We only want a small amount of fuel to flow (air to flow) at 1/5 throttle opening. This low end needle setting will get your engine running and may require further adjustment. THis is just a ball park setting.

Now close high end needle valve and open carb to full throttle. Blow in fuel tubing and simulataneously open high end needle until you have FREE FLOW of air into carb. You should not experience as much resistance to airpressure as you did on the low end. Your needle valve should be open between 2-5 turns (it all depends on the carb folks).

This procedure gurantees you don't have a blocked carb or closed needle settings for low and high. This will get you in the ballpark which then will require you to fine tune your low end and high end for best performance--highly recommend the pinch test .




Start engine and use the following procedure to fine tune your engine once it is running and warmed up:


Pinch test procedure:


First start engine this way:

Prime engine by opening up throttle to full and blocking exhaust with finger. With blocked exhaust, rotate engine until fuel just enter's the carb-watch fuel line to see fuel displacing the air in the fuel line.

Reduce throttle from full to about 1/5 throttle opening. Apply glow ignitor and rotate engine (hopefully w/ starter) counterclockwise (for 99% of all engines out there) until engine starts. When engine starts, move throttle to 1/2 throttle and then remove glow driver.

If engine won't start, try more throttle until it does. If engine will only start above 1/2 throttle, it means your initial low end needle setting was too lean. Richen it about an 1/8th of a turn until the engine starts at a low throttle (1/5 throttle) setting.

If engine will not advance to 1/2 throttle when glow driver is on then leave at 1/5 throttle with glow driver until engine is warmed up-about 2 minutes should do the trick.

Advance throttle again to 1/2 throttle slowly. If engine dies then your low end needle is probabably too lean. Richen by 1/10 increments.

Once you can get your engine running at 1/2 throttle then its time to remove the glow driver/ignitor. With ignitor removed, advance throttle to full throttle. Chances are your engine will be too rich and may even quit. If so, briefly pinch and release fuel line as you advance to full throttle to verify the mixture is too rich. If it is too rich, then in small increments lean it out until it will run at full throttle without quitting. This does not mean the high end mixture needle is set. This is just a starting point to ensure your engine is running at wide open throttle (WOT) so you can make the proper adjustments.

With engine running at full throttle, slowly and carefully lean the high end needle valve until the engine is spinning at its max rpm. This can easily be determined by sound alone-no tach needed. This is where engine is producing most power but the mixture setting will cause the engine to run too hot and overheat. So, as a safety feature, always richen the mixture about 300 rpm shy of max lean rpm. Verify this by briefly pinching and releasing the fuel line to the carb. If the pinch test causes the engine to speed up and back down, then you have correctly set your high end needle setting. If engine doesn't speed up much or dies then you are still to lean and need to riche the mixture slightly until it passes the pinch test.

You are almost there. With high end needle setting set about 300 rpm rich of max lean rpm, recheck idle and transition. Let engine idle for 30-60 seconds and then snap throttle to WOT. If engine hestitates in the transition, fine tune mixture so that the transition is snappy and idle is reliable. I personally like a lean idle mixture so I can idle for long periods without fuel pooling up in the crankcase which causes stumbles when transitioning to full throtttle. You can also use the pinch test when the engine is idleing. Pinch and hold fuel line with engine at a fast idle. Engine should speed up and die about 4 seconds. If it takes longer, your low end needle is too rich, if it takes less time or if your engine dies instantly, you are to lean and need to richen your low end needle. After every adjustment to the low end mixture, you must recheck the high end mixture. Otherwise you don't get the correct settings, and the next time you check your high speed needle, you'll screw up the low end.

Once low end needle is set, you will probably never have to adjust it again. However, your high end needle should be checked before every flight by doing the pinch test at WOT to verify the mixture is slightly rich. This 5 second test and adjustment, if necessary, will gurantee you a reliablie engine that will last a long time. Our carbs do not adjust for changes in temperature, humidity, barometric pressure, etc... and a small change of 5 degrees in temp can cause a properly tuned carb to be out of tune and possibly too lean (or too rich depending on whether it gets hot or cold outside).

Hope this essay helps the newcomers to our hobby and prevents them from becoming one of the set it and forget it crowds that do not benefit from optimum tuning for the best engine performance and longevity out of an engine.



PS An engine may not idle or transition as it should when it is new and not fully broken in. Use these instructions to get your engine started and then do the appropriate break in (rich 2 stroke if it is an ABC type engine or even richer if it is a ringed engine or 4 stroke engine).
Old 03-06-2008, 12:53 PM
  #4  
Senior Member
 
goirish's Avatar
 
Join Date: Dec 2005
Location: Litchfield, MI
Posts: 5,130
Likes: 0
Received 0 Likes on 0 Posts
Default RE: How to break-in engine

I know on one of these threads they advocate breaking it in on the plane. I like to use the bench method only because I can be breaking in a new engine while I am building or assembling a plane. That way I have all of the bugs worked out and it is ready to fly when I take it to the field. Also, I don't get all that slobber on my new plane from running so rich. Just my 2c worth.
Old 03-06-2008, 12:58 PM
  #5  
Thread Starter
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default RE: How to break-in engine

goirish I hear ya, I just don't have a place for an engine mount; much easier to build plane (on the dining room table) take it to a field and break it in.
Old 03-06-2008, 01:00 PM
  #6  
 
bingo field's Avatar
 
Join Date: May 2004
Location: Mt. Morris, NY
Posts: 1,732
Received 3 Likes on 3 Posts
Default RE: How to break-in engine

It's funny that you mention the slobber clean up.. On my Venture, when I broke in the Saito 91, I ran a short chunk of old garden hose into a quart oil container to collect almost all of the stuff. Just cut a 3" notch in the end of the hose that goes in the oil container so there is no backpressure. I had nearly a half quart when I was done. The reason I do it on the plane is because I do it outdoors anyway, and I get to find out if the tank is in the right position along with the final plumbing.
Old 03-06-2008, 01:01 PM
  #7  
Senior Member
 
goirish's Avatar
 
Join Date: Dec 2005
Location: Litchfield, MI
Posts: 5,130
Likes: 0
Received 0 Likes on 0 Posts
Default RE: How to break-in engine

Got it. We make do with what we have, Right. Humm!!! wife won't let you mount it on the dinning room table. Geeze just not a lover of the sport. Tell her it would take the place of a fan in the summer
Old 03-06-2008, 01:03 PM
  #8  
Senior Member
 
goirish's Avatar
 
Join Date: Dec 2005
Location: Litchfield, MI
Posts: 5,130
Likes: 0
Received 0 Likes on 0 Posts
Default RE: How to break-in engine

makes sense to me Bingofield. How did you come about that screen name. Do you fly the Bingo and Big Bingo?
Old 03-06-2008, 02:31 PM
  #9  
Senior Member
 
Missileman's Avatar
 
Join Date: Feb 2006
Location: Poland, OH
Posts: 3,204
Likes: 0
Received 0 Likes on 0 Posts
Default RE: How to break-in engine

In answer to your original Q. I do the same as post #2. Put a stake SECURELY in the ground, take a pirce of rope wrap it around the tail and tie it to the stake. At home I tie off to the picnic table.
Old 03-06-2008, 03:16 PM
  #10  
 
bingo field's Avatar
 
Join Date: May 2004
Location: Mt. Morris, NY
Posts: 1,732
Received 3 Likes on 3 Posts
Default RE: How to break-in engine


ORIGINAL: goirish

makes sense to me Bingofield. How did you come about that screen name. Do you fly the Bingo and Big Bingo?

Navy origin for an alternate place to land in the event you can't make it back to your originating carrier. I fly at my own field, and it started out as a very makeshift field, so that's what I used.

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
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Thread Tools
Search this Thread

Contact Us - Manage Preferences 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.