Engine Break-in

roc111672

3D Farm Bartender
I was wondering how long it will take for an engine to break-in if i use 50:1 Stihl Ultra HP from day 1 ? Also how can i tell when the engine is broken in ?

Thanks , Rusty
 

earlwb

Active Member
I typically don't use 50:1 on a new engine right away. But it depends on the engine manufacturer as to what they suggest. I use something like 32:1 at first for a few fuel tanks of fuel on a new engine on a test stand. Then later as the engine gets broke in more switch to the fuel/oil ratio the engine manufacturer says to use. A engine typically takes a hour or more or run in time to get broken in. But you really want to finish the break in process flying the engine in a airplane so it is subjected to flight loads and stress reather than on a test stand in a static situation. I run the engine on the rich side when flying a new engine and gradually over time I can lean it out more. Some engines are very long wearing and don't wear out very fast at all, and these engines may not get broken in good for several hours or more of runtime.
 
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BRUTUS

Plank Junky
Lifetime Supporter
Is there any real advantage to breaking an engine in on Synthetic? I know it would take way longer to break in, so I don't understand the benefit.
 

Jaybird

Wishin' I was at the farm
BRUTUS said:
Is there any real advantage to breaking an engine in on Synthetic? I know it would take way longer to break in, so I don't understand the benefit.
The only benefit to me is just using one fuel can/mix for everything. I fly enough that break in taking a little longer isn't that big of a deal to me.
 

Tired Old Man

Staff member
What reason is there to break an engine in on a faster oil? I break all engines in using the oil and ratio they will be using for the life of the engine. My break in methods are pretty similar to what a particular company does in their break in process. After a little over 8,000 engines I figure they have all that figured out by now.

Total break in time will be between 5 and 10 hours at 50-1 using Stihl HP Ultra. About the same using 40-1 Redline, which will be about the same as 32-1 Pennzoil. Bottom line you want the engine to experience numerous heat cycles, not be over heated, not be run rich, not be run cold, and flush break in debris from the engine using the oil evacuation process that is natual to a two stroke.

You have to break in a glow engine if you want to obtain maximum life and performance from it and that also takes time, along with considerably more work to do it right. I don't understand some people's desire to force a mechanical device the requires close tolerance lap fitting to wear faster than it needs to in order for it to reach maturity faster. It's like using 80g paper on a finished wood product just to pull the material down faster. Nor do I understand why people fail to understand the heat cycle process also has considerable impact on the metalurgical condition of cast engine parts such as the cylinder, and witrh many high end engines, the case. An engine where someoone has tried to expedite the break in process will not be as good as one that was handled correctly. The truth to that can be found in all the stuck rings and burnt cylinders removed from new engines sent back for warranty work. There are a very great number of them to choose from. Those that do this stuff every day tell you to do things a certain way because it has been proven to work, work well, and work all the time.

People can do things with their engines any way they want to. They bought and own it, so have at it. OTH, those of us that do this professionally have a lot better running engines than you do and they last a heck of a lot longer. That frees our time up by minimizing repairs in our engines so we can do the repairs in yours.
 
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Classclown

Well-Known Member
And for God's sake, tune the engine from the very beginning for top rpm, don't run it rich, it's not a glowtard engine.
 

BRUTUS

Plank Junky
Lifetime Supporter
Thanks for clearing that up Pat.

So, like everyone says- tune it for peak, fly the snot out of it. Run whatever oil you like at the recommended mix, and heat cycling is important.

Got it.
 

Classclown

Well-Known Member
I never broke any of my dirt bikes in on different oils either. Didn't baby them. My friends that broke their bikes in, taking it easy, ended up with slow bikes. Just don't over heat them. Many heat cycles, break a motor in properly.

When I started flying gas, the DA manual said to use Lawn Boy, like a jacka$$, I did. Momentary lapse of reason...
 

BRUTUS

Plank Junky
Lifetime Supporter
All Aeroworks engines are still run on Lawnboy... From day 1. They pull them out of whatever proto they are on, slap them into the next proto and do it all over again.
 

ben_beyer

Junior Member
I use the Quicksilver Premium 2 cycle oil (it's also rated TC so it's good to go in air cooled engines but don't grab the Premium Plus). I use this mixed at 32:1 and then switch to synthetic at 40:1. I'm sure the non-synthetic Stihl oil would be another good option for break-in.
 

roc111672

3D Farm Bartender
Well I run Stihl ultra HP 50:1 from day 1. Have t had a problem yet so I will keep it like that.
 

terickson

50%s speedbuilding school
I thought oil threads were only allowed for wintertime entertainment when it's too crappy to fly!
 

Tired Old Man

Staff member
I'm sure the non-synthetic Stihl oil would be another good option for break-in.
The non synthetic is indeed a good oil but I can assure you it is not tolerant of lean tuning or hot running. I found that out when using the stuff to break in a new Taurus engine some years ago. It started to stick a ring in the first three hours of run time.
 

earlwb

Active Member
I do not have a problem using Stihl Ultra oil for a new engine. When you think about it, the manufacturer suggests using their best 50:1 oils on their new utility engines anyway. it is in the owner's manuals. So using the better oils is not a problem as far as I am concerned. I prefer to use a higher oil ratio for the first few fuel tanks the engine is run though. Since the engine may be a bit rough and more coarse on the inside the extra oil helps out some as you don't know how much the internal parts were oiled to start with, and I want it oiled up good, especially for the connecting rod. Plus I take it a little easy at first too. I know some guys break them in hard and it tends to work. But I still see people trash new engines trying to max them out for that first flight too. So I prefer to be a little easy on the engines at first. Your choice.
 

Tired Old Man

Staff member
Most new engines are not oiled at all unless the maker ran it before they shipped it. So you are correct to use caution with a new engine. But there's a way around that. Before you install a spark plug run a few (like several) drops of your oil of choice down into the cylinder and rotate the crank a bunch of times to get the stuff flowing down the cylinder walls.
 

earlwb

Active Member
Yes I do that with the new engines too. But even though the newer engines use lower oil ratios, I like to ensure the connecting rod bearings are oiled up good. I would hate to have one get galled up from being dry on that first engine run. So sometimes I remove the reed block assembly and oil up the insides good. With cheap engines flushing out the insides is a good idea as it is pretty common to flush out some little metal bits and pieces left over from manufacturing. On a couple of occasions some really big pieces of metal fell out of a engine on me before. That had me trying to decide if I needed to tear the engine down for a closer look or not then.
 

BRUTUS

Plank Junky
Lifetime Supporter
I put some bowman rings into an old DA-100, and man those things were a TIGHT fit. There was bordering on zero ring gap, and even with some light oil in the jugs the first start while flipping the motor over the rings were creaking in the jugs- but after 2 seconds of run time the oil in the fuel did it's job and the motor started running smooth as silk.

As a side note, I only have a gallon or two through the motor so far, but the compression is at least double what it was before the new rings. The motor itself had a complete top end rebuild shortly before I upgraded to Bowman rings, but I left the main crank bearings alone due to budget constraints. Within one hour of run time with the new rings the old (like 12 year old) crank bearings started feeling a little gravely if you know what I mean. Not related, but I suspect the better compression and power output pushed the old bearings over the edge. Motor should be arriving at DA for new bearings tomorrow.
 

JohnBer

Well-Known Member
think the bowman rings are needed on a DA? I put em in my china motors and like the results increased comp on all. but my DA has great compression stock. I am sure the fit is better than the china motors. kinda one of those "if it aint broke" deals. wonder if DA gives ya (or sells ya) a new set of stock rings.
Not sayin anything bad about bowman rings, i am impressed with em.
 

RTK

Well-Known Member
I'll throw in my 2 cents on my break in procedure.
Tune needles on the ground for good transition and running, use same oil I do in everything.
Take it easy for the first couple of tanks and re-tune the needles if needed for in flight characteristics.
Then beat it like a red haired step child, normal flying.

No one breaks in a chainsaw, weed wacker etc. As long as you don't over heat and run with a proper mixture all will be good.
 
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