Hello
I have a Moki(mark 1.35) and have used it for the past 4 months, coupled with a perry pump Vp-30
I think I has ran through 3 gallons or so of fuel.
It is swinging a 17x6 in anultimate 120 from carl goldberg, awesome power, Last weekend was the first I decided to fly it with the cowl on, very unsteady performance after 20 seconds of so airborne, is starts tumbling and sounding like it was going to give me a dead dtick.
AFter two failed attempts I removed the cowl for the fourth fly, and it just ran beutiful a lot of power and very stable.
I think that when an engine varies that much with and without the cowl is due to the overheating (i provided a lot of free space with moto-tool the day before) and my cwl looks like it is going to crack since is plenty of large room now bewteen the engine and the cowl (to ensure proper ventilation).
Nontheless I just start thinking that this engine has not yet broken in and it still needs a couple of gallons to go through.

Any experience anyoneone would like to share with this engine's break in?
Thanks in advance
Omar

Sounds like it is over heating?

You need baffles inside the cowl to direct all air through the fins. No air can get past the engine otherwise

I also have a 1.35 and it was a dead-stick queen until about the third gallon. Running nothing other than FAI or 5%. After about three gallons it started running great and is one of the better engines in the stable! Can't help on the cowl issue though as mine runs uncowled on an 86" Rebel.

Hello Happypappy,
Where did you find your 1.35? I had a new one in the box and gave it
a "heat treatment" with a product named "ER" (Energy Release).
It's a liquid I put in the new engine and then 300 degrees for 2 hours in the oven. In years past this worked great on new engines and greatly shortened
the break-in running time. But it ruined my 1.35 The engine locked-up,
with the rod frozen to the crank and corrosion throughout the inside of the
engine. So it's ruined. As I said, I've done this same treatment with many
engines in the past and nothing like this happened. I'm guessing they changed
the formula on the ER. I will never try this again.
Anyway, I want to use a 1.35 on a Balsa Nova 80.
Where did you buy yours? Do you know if they have any more?
Or do you think I should just go with an OS 1.20?
Regards
JC

I kept looking here for it until one showed up and bought it. There are still a few around if you are patient. As far as the OS 120 is concerned it is a fine engine with good running quality. The Thunder Tiger 120 Pro also falls into that category as well.

Here you go. Found this tonight. The Mark engines are the Moki engines you and I know. http://www.chiefaircraft.com/rcmsec/...Mark.html#m135