Just out of curiosity, why is it that a DA-50 needs 5 gallons to break in (at least mine did when I had it a couple years ago) and so does a DA-100? Each cylinder in the 100 is only seeing 2.5 gallons.

Just curious.

My DA 50 manual says at least 2-4 gallons..my first one I did 4 and my second one I did 3..

I break all my DAs in with at least 5 gals of amsoil at 80 to 1 . Thats from the start. Have never sent one back>

Kent

I guess they changed the manual since I had my 50. Makes more sense now.

Cheers.

It's an arbitrary number anyway, the WAY the engine is run has more to do with it than how long...
CYA for DA...

Ralph,
Could you please elaborate on that statement some? The reason I ask is because I'm currently breaking in a small gas motor and I'm looking into building a 50cc gasser. I hate that nasty black spotty Lawnboy Ashless crap all over the bottom of my current airplane that I have to clean up when I fly, but I know it will go away one day. My question is, is it possible/feesable/practical to break in a gas engine on a test bench to avoid all the nasty problems you get while breaking in on a plane? If so, how would you do it. (Run times, throttle, needle settings ect.) I plan on buying my 50cc gasser a piece at a time (as funds become available) and if I can break-in on a bench I'll buy the engine first so I can run it in while i'm collecting the rest of the parts.
Thanks in advance for any advice you can give.

Josh

Running on a stand will let you get familiar with your engine before you put it in a plane...The only parts of a gasser that change with use are the piston rings and bearing seals, nothing else in the engine changes much...There is no break in on ball and roller bearings...
Zenoah recommends running the engine in the plane, just a little richer for the first few tanks..
When you can look at the piston rings and the finishing marks are gone they're as good as they will ever get, the engine is broken in....
Maybe the DA engines are set up with closer tolerances between the cylinder and piston...Running rich and not quite so fast lets the high spots on the piston wear away without the engine getting hot and seizing..
I make sure the high needle is set just a little rich and the low as lean as possible for good transition, then fly...

Because 5 divides into 50 evenly, It's a DA 50. [sm=bananahead.gif]

Seriously now, I have a DA50 with 2 1/2 gallons and I was thinking of doing the switcharoo a little early. I can use my two remaining cans of Lawnboy ashless in my Lawnboy lawn mower and weed wacker. I'm still trying to decide which synth oil to use. Probably the Amsoil 100:1. The other contender is Bel Ray with their HR1 or MC1.

RCIGN1 what do you use?

Pennzoil 2 stroke or Blue Marble..
We use Klotz KL200 in the race engines, 8 oz to a gallon...

Im breaking in my DA100 with Mobil Mx2t synthetic right away at 32:1. I probably have a little over 2 gallons on it. After talking to Brian from DA at the Wram Show and finding out that he prefers to break in his engine with non synthetic. I am considering switching to non synthetic for the rest of the break in process. I am wondering if it is a bad idea since i already used synthetic oil? Would it cause any harm on the engine?

Smokey

Thats what I did on me second DA 50..I ran 3 gallons thru and went with Amsoil at 80:1 and its running perfect..My first one I ran 4 gallons of Lawnboy..

Hmmm... a guy from DA told you the same thing the manual says... interesting concept...

So - how do you know when your engine is broken in?
--
What would happen if you simply adjusted the engine for best overall performance -then simply kept it from overheating?
Is it even remotely possible that ---the engine might survive and actually suffer no damage?
Perhaps even perform extremely well from then on ?

No doubt about it.

First time I started my DA, it was on Amsoil @ 75:1. I heat cycled it a few times, just blipping the throttle easy and getting it good and warm, but not too hot. Ran a tank thru doing that. Next tank I trimmed out the needle settings for best stick response and highest rpm. (then added just a touch more fuel on the high needle) Then I started flying. It ran flawlessly from the get-go, continues to run flawlessly, and I expect it to keep doing so for quite a long time. My Brison got the same "break-in." As they have accumulated run time I have had to lean out the low needles on both a little bit, but there have been no dramas at all. I basically don't even have to clean my planes, since they aren't blubbering oil pukers.

All this fancy recommended break-in is just wasted time and oil on a nikasil cylinder engine, that's my (a full-time engine builder) opinion. The manufacturers recommend what they do just for CYA. That way inexperienced users get at least 5 gallons of flying before they get happy on the fuel needles and detonate the thing to destruction.

Last 3 posts, Couldn't have said it better

This is my favorite part. I couldn't agree more.

Detonate the thing to destruction, thats it. Then it's broken in!

I still don't find that my motors get any stronger with time like many people seem to claim. RPMs from day one or two don't change all that much from what I experience. ZDZ, Brison, and 3W, all still making the same RPMs from new.

Its more like this hunk of scrap motor better get stronger or else

Wishfull thinking!

Wow.....that's strange.

Karol

It probably gets strong after they start to actually tune it.

Only way it can get stronger is better tune, like he says, or if the engine was really tight at first...Claims of 800 more rpm are highly suspect...
Most of the G26s turn around 9000 out of the box, maybe a little more with use...

I think you just hit the bull's eye

Karol

Though this is a bit off track from the original post, do gas engines unload in the air as glow motors do, and if so by how much.

Karol

About 1000 RPM. You know that really loud ripping sound you hear at part throttle? That's unloading.

Depends on the prop and the plane..Our GT80 stock engines unload from 7500 on the ground to 9000 in the air..The race versions on methanol unload from about 9000 on the ground to almost 12,000 in the air...
Our 289 racing twin unloads from 7200 on the ground to over 9000 in the air..
We use data loggers and telemetry so these numbers are valid...