well my ax55 will idle all day and transitions great (1 flip starts) but their is this one spot, just past idle but not more than 1/3 open where the engine seems to run fine then all of a sudden dies.
this has caused way to many deadsticks for my likeing and due to my luck, this is where i run my engine when i am doing harriers (mojo.40)
i had this problem with a os fp 40, and seemed to solve it, but that was with an airbleed carb and not a twin needle. (high end was to rich while low end was a hair to lean, after i fixed that the engine runs like a top, 1 flip starts as well)

this engine is on a profile, so i can see the lines/tank. the engine likes to die when its 2/3 full (8oz).
the fuel was foaming but i thought i fixed the problem, ill doubble check to make sure i did.

has anyone else had this expierence? run fine but dies at one setting (1 click up or down and it wont die)
the engine is still breaking in with maybe 1/4 of a gallon through it.

Take the carb apart and scrub it with a toothbrush and denatured alcohol. I had a similar problem on my 120AX and that solved it. Sounds like junk in the carb.

...just my thoughts...

Some profiles can shake like crazy in flight. It could still be foaming, use real urethane foam to isolate the tank. http://www.shopatron.com/product/part_number=514/101.0 OS bubble-less clunks http://www3.towerhobbies.com/cgi-bin...&I=LXXF25&P=ML are amazing when used in conjunction with foam rubber. Poly foam(white) doesn't cut it. I'm seeing a lot of guys recycling the stuff that their home electronics came in, good for impact, but poor vibration dampening.

Are you using an APC 12.25X3.75? that seems to be the prop of choice for a 3-D profile.
Did you take the baffle out? That can cause a hideous flat spot at part throttle and out right kill it if you have other issues.
I don't like the "Power Box" muffler, if the baffle is removed, you gain an instant 1000 rpm, but at a cost.

im useing a 13x4, may switch to a 12.25x3.75 to see if that helps (at least for the rest of the breakin)
and yes it shakes like crazy

I have the same engine and went through the same problems with a profile funfly. I found that the 12 1/4 X 3 3/4 prop was not enough prop for the engine. It flexed during transition and this caused the foaming. That prop is better for a strong 46 engine. I used a 13 X4 APC wide blade and solved the foaming problem. Regarding the engine quitting on spool up, I had to richen up my low end some, and this eliminated the deadsticks.

If you are still on factory carb settings, run the engine some more for break-in. Then start leaning the LPN. On mine it took 1 1/4 turns in to get it to not dead stick on take off. Runs great now. 13x4W apc.

There are no factory carb settings. There is no way that the factory folks can know where the centerline of your fuel tank will be in relation to the carb's spraybar. Furthermore, they can't possibly know what brand of fuel you will be using, nor will they have any idea of its contents. Additionally, even the best guessers in the business can't possibly know what kind of propeller load your engine will be expected to deal with. In other words - there is no way that the factory can anticipate what your engine will need as far as carb settings go. Our model engines are unlike any other IC engines that we are likely to encounter in our lives.

Now I'm not saying that you do not know this information. I am writing it here for those that do not know this information. Forget "factory settings" when it comes to glow engines. There aren't any.


Ed Cregger

Every engine I have bought new had the LSN and HSN installed in the carb, not laying in the box. This is the factory setting. They set them rich to keep a new person from running them to lean. The instruction manual says ( mixture control valve of carb is set at basic position at the factory, alittle on the rich side ) I didn't make this up, it is in the OS manual.

Stunt-man,


Foaming is not the problem...

It is the vibration of the tank walls that cause the clunk to be deflected off them, into spaces in the fuel-tank where air resides; in turn causing this air and gaseous methanol to be ingested into the fuel line...

No matter how strong the vibration level is, glow-fuel is not milk-cream that one can churn into butter...You cannot churn it into a thick, rigid froth, that will prevent the clunk from sinking rapidly back into the drink...

Formation of a tankful of 'fuel-foam' only requires a very small amount of liquid fuel, that will not significantly lower the level of the fuel.

And I am not accusing you of lying. I'm just trying to clue some folks into what is really going on with their two-stroke and four-stroke glow engines. Good luck in the future.


Ed Cregger

Perhaps the term "Foaming" of fuel is not a technically correct term for when a sufficient volume air bubble are in suspension in the fuel to cause a lean condition however, that seems to be the phrase that is most in the hobby relate this condition to. If you have a better name for it....name it, but don't expect change.

I can't say I have ever witnessed a clunk bouncing around a tank to the point that it breaks the fuels surface, but in a real shaker, I have seen red fuel turn pink with air infusion from vibration and recirculating fluid (looked like it was boiling) in the tank with both Wildcat or Powermaster fuel.

In any case, tank isolation can't hurt or go with a bladder tank for severe problems.

i ran it today, was going to fly but noticed tail problems.
i richened the low end a little and couldnt get it to die on the bench (but i couldnt get it to die before). also i was watching for foam but didnt notice anything out of the usual
i may get out tomorrow and see if more foam/fixing the idle may fix it

Thanks Freakingfast. Couldn't have said it better myself

idle was a little lean and high speed was to rich. adjusted highspeed, then idle, then went to that one spot, it loaded up a little so i leaned my highspeed a few clicks and it was all good from their (i set my highend a little to rich most of the time) havnt had a deadstick in a 5ish tanks

Quote:

ORIGINAL: jimmyjames213

...Then I went to that one spot, it loaded-up a little so I leaned my high-speed a few clicks and it was all good from there (I set my high-end a little too rich most of the time) I haven't had a dead-stick in 5 tanks.

JJ,


You are probably just a bit lucky and luck has been known to run-out...

Leaning with the high-speed needle, to overcome a rich condition at part-throttle, will only make the engine leaner at the top-end, without affecting the low-end...
If it was set too rich there, it will work only there; and there is no chance it will affect the mixture at less than 75% throttle.


If it did help somehow, there is something seriously wrong, defective, or dirty with your carburettor.