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Was told to repost this here in case someone can help. OS AX .46

Old 04-15-2007, 07:24 PM
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Default Was told to repost this here in case someone can help. OS AX .46

First, I finally flew my plane today for the first time after a while of waiting. It had flown with my buddy who made sure it was working but we had to make a few mods and such including some orange flashy covering to see it better. Anyways, it was a lot of fun but I have run into a small problem.

The first time I ran the engine after the first tank ran through at least partially and it had warmed up I couldn't get the engine started again This was a few weeks back. It just won't fire when it's warm it seems. Today again, I went out we flew a flight till it had to be deadsticked in cause it quit after about 12 to 15 minutes or whatever. Got it fueled up and no go. We tried playing with the throttle, the plug is fine(we checked it and the glow plug starter was turning it red hot. Everything just seems to be ok but it just will not fire and like I said, it's not the first time. I know that when it's cold the compression is very tight. It's an OS .46AX and you can feel it's tightness at the top of the cycle. But once it's warmed up it turns over much easier. The starter actually would sometimes get caught in the middle of the compression when it was cold(the starter isn't the most powerful ever but it's enough to turn it over and it should start). Anyways, it doesn't have trouble in mid compression once it's run a fuel tank so it's much looser.

We tried thinking up the reason. We played a little with the high speed needle valve and we tried a few other things(making sure the fuel was running through and stuff). But no luck at all.

Then it dawned on me. What if it's the fuel. I have old fuel. I used it when I first flew about 5 years ago but it's been sealed and was told that it should be fine as long as it's sealed. I'm wondering if it's just not got quite as much kick and once the engine has warmed up, maybe it's not enough to fire? Is this possible?

Is there another reason that you can think of? I'm using 18% oil type fuel with 10% Nitro. It's Byron fuel.
Old 04-17-2007, 10:21 AM
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Default RE: Was told to repost this here in case someone can help. OS AX .46

Fuel would not be a problem if the engine will run fine with it once started. If an engine won't start when it's warm, but will start when it's cold, it usually means that the piston/liner fit is on the loose side. If you have ANY compression, though, when it's warm, you should be able to get it started if it's properly-primed. If the engine will run and idle properly, once you get it started, though, compression doesn't sound to be a problem.

Perhaps the engine just needs more running time to get a good break-in. Most engines need a gallon or more run through them before the really get a good 'set' of the parts. Ringed engines take more running than the ABL engines.

If you have doubts, you can certainly send the engine to us to be examined.
Old 04-17-2007, 03:09 PM
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Default RE: Was told to repost this here in case someone can help. OS AX .46

Turns out it might be the fuel after all... The fuel line in fact. I flubbed and put the exhaust pressure tube pointing into the fluid. I misread the directions and should have known better but I didn't have prior knowledge of what the correct way should be and the directions were vague to say the least. Someone told me it will create bubbles in the fuel and that's why I was getting bubbling through the line to the tank. We did get it started cold again later the other day but it was starving and died after 3 minutes on the ground of bad idling. That is probably the case(lack of fuel). So it's now fixed but I haven't gotten out to try it yet. Yanked the battery out and broke the black wire off of it so I had to get a new battery and charge it(will have to fix the old one sometime)
Old 04-17-2007, 08:48 PM
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Default RE: Was told to repost this here in case someone can help. OS AX .46

Well it's a working. The tank was the problem after all. Strange that it would run cold but once it got warm it just wouldn't run when the exhaust pressure line was fed into fuel and not into the top of the fuel tank.

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