I have a Moki 2.10 that gave me problems on Sunday.
It has 1.5 gallons through it and it is a strong running engine. However I was on my 2nd flight of the day flying the pattern when I thought I would try to perform a blender. After the maneuver I noticed that my Moki was making a sputtering sound. I immediately landed figuring that it needed some needle adjustments as it is still in the break in .

I landed, took a 10 minute break, topped off the tank and tried to start it. It wouldn't start. Finally after about 15 minutes it started. However as soon as I would try to transition from idle to full throttle, it shut off. Each time it shut off it took 15 minutes to start back up.
Any idea what could cause this behavior?
I let it sit for about 1/2 hour figuring that maybe it was overheated. That didn't make a difference. I'm puzzled. I don't think it is the low end as it ran perfectly on the first flight.

Could the blender have caused an overheating problem?
I am running byron 5%
K&B1L plug.
Bambula 20x8

Have you tried a new plug? Checked the clunk line in the tank to be sure it didn't flop to the front of the tank?

John

I removed the K&B1L and stuck in an OS#8 with no success.
I didn't check the clunk, however the tank was full and when I pumped the gas from the tank it pumped out fine.

I had a similar problem the first time I took this plane out to the field. It was overheating. I added a little baffeling and the next 2 times it was fine. Although I hadn't done any 3D with it. Basically I just flew the pattern at 1/2 throttle.

I guess that I can try starting the engine again tonight and if it runs ok it must have been an overheating issue. Would you agree with that?

If that is the case. Is there anything I can add to the Byron fuel that will help the engine run a little cooler? I have 1/2 gallon of 5% left and I will drop down to 0% which will also help.

If the clunk line is partially kinked, it will restrict fuel flow, but maybe not enough to tell when you are pumping the fuel in. Can you fly the model with the cowl removed? This will tell you if it's over heating or not. If you can see the back of your tank while it's in the model, you should be able to see the clunk swinging near the back of the tank. Since you didn't have any problems until you tried some 3D stuff, this is why I immediately thought of the clunk.

From what I have seen, Byron fuel measures the oil content by weight, not volume and many have said that the content is lower, by volume since the oil weighs more than either methanol or nitro, than other fuels. An increase in oil couldn't hurt. A couple of ounces of castor couldn't hurt you or your engine and would be worth a shot, but I would check out that clunk line first myself.

John

JWN
Thanks for your help. I will check the clunk. I didn't think the clunk was the problem, however, i did install a large clunk which is a little heavier than standard and would probably fall forward a little easier.

Where can I buy castor? A hardware store? Any special brand? How much would you add per gallon? Sorry for all the questions as this is new to me.
Will castor in the fuel help with overheating without fowling out all of my plugs and killing engine performance?

Once again thanks.

If your local hobby shop is a good one they'll have some Sig castor in a quart bottle. It's the good degummed stuff.

Thanks to all. So how much castor should I pour into 1/2 gallon of 5%?

The oil content of your fuel should not be the source of your problem That engine, when properly broken in, will easily run at a lower oil content -- the the level you us for the big Super Tigers, but definetely with the level in Byrons.

I agree with the other posts -- it sure sounds line fuel line. BTW, putting in a large klunk won't help unless you make everything else large (klunk fuel line, brass tank line, and fuel line to the carburetor.)

Also, what is the relationship between the tank and the engine. You want an optimum setup with the tank less than 12" from engine and the level with the carburetor. If that is not the case invest in a Cline Regulator.

Crash:

Since the engine ran fine until you did the blender I'd be far more inclined to blame the clunk shifting than blame the engine.

The problem, however, could be a cumulative thing.

In my opinion, the Byron fuel in a Moki is maltreatment. The Moki wants more oil, and it prefers castor.

Go to your grocery store, get Baker's AA castor oil, or to your local drug store and buy USP castor oil. Or, as stated earlier, Sig castor from your LHS. The LHS with the Sig label is also the most expensive way to buy it.

Then add at least 2 ounces per gallon of Byron fuel and you should be OK. Might even like it better at 3 ounces per gallon. In either case it wont change the percentage much, 3 ounces per gallon is just barely over 2%, 2 ounces per gallon is right at 1.5% added.

Bill.

Also check the carb inlet. I found some burrs inside and had to clean it with a bit.