http://www.valak.net The link to the video is on the page. Note my friend's reaction

Anyways, 5th or 6th flight of the day, plane flying smoothly and engine running well. After take off, I take the plane vertical and start a right aileron roll. Just after I start, there is a loud "pop" and the engine dies. The landing was quite scary but was uneventful. I brought the plane back to the pits to see what happened.

Turning the propeller like you would to prime the engine, there is a constant friction. The engine still has good compression. A friend said that a bearing might have seized up or something like that. Everything seems normal except for the friction.

The engine is a Saito FA-100 turning an APC 15x6 prop like I've always used. Nothing bad has happened to this engine until now. I turned the needle valve to get max RPM until it started to fall off, then turned it back maybe a half a turn to 3/4 turn. Its been in this position since I completed the break-in process.

Any help would be appreciated.

i just heard a couple of days ago that a friend said he had a 4 stroke that did the same thing(loud bang and stop running) he said he tore it apart and it was the valve spring that broke. You want to tear the motor down any way to find out what happend. if you cant do it im sure someone in you club can. good luck

Obviously, I wouldn't try to run it until after it's been dismantled and repaired. The constant friction could be anything, but my guess is that it's probably a broken bearing. If it were a broken valve spring, you should notice a complete loss of compression.

This thread probably belongs over in the Engines Discussion forum.

This happened to me with my YS120. It was my piston pin! It has been repaired and is on a 1/4 scale edge. Lots of power and no problems!

I've been running saitos for years and have had only minor problems running them. I've been very happy with the brand. Anyway, I've run cool power 15% for ever in my 150s and 180s and I bought some hobbytown 15% fuel made by wildcat. I always have my motors on the rich side so I don't do much adjusting of the needle valve unless the weather really changes. Anyway, first flight with the new fuel and 5 minutes into the flight, deadstick. Bring it back to the pits, start it up and now it dies at full throttle. Backed it off a full turn until it was running rich again. Flew a few more flights no problem. Finished up that gallon, went back to the cool power. I needed to turn the needle in a full turn. Later, opened a new bottle of the hobbytown. Turned out the needle full turn and flew a flight. Turned it in 1/4 for the next flight and had another deadstick. Anyway, I guess what I learned is that not all fuel is equal. You may have a problem with the motor but 4 strokes tend to just stop if they're too lean where as a two stroke changes pitch when it's too lean and then freeze up and quit if you don't recognize the warning sound. Especially when you pull to vertical. 4 strokes by the way can go very lean when pulling vertical. Did your motor die while climbing? The only way to really now what a 4 stroke is doing is to use a tach. However, I found with my new fuel that my range of adjustment on the ground was broader than with my usual fuel. Although it didn't appear to me or by my tach to be lean on the ground, it was leaning out enough in the air to cause it to stop with the different brand of fuel.

Thanks alot for the replies. If you didn't get the video, its now working. ISP was screwy the last couple days.

da king: About the possibility of being the valve spring, Im not big on taking my engines apart. Could this be something covered under warranty?

mkirsch: Same thing above, would this be covered under warranty or would it be considered a "user error" ?

JIMMYTHEEAGLE: Yes, the engine died while going vertical. Right after take off I put it straight up. After a few seconds, BANG and down it came. The fuel I use is Wildcat 4-cycle/YS 20% nitro / 20% oil.

nex ya that should be under warranty. i saw the video and i cant see what you did wrong. why are people so afraid to tear apart a motor??? either way i would sent it in too have it looked at. you have a 50/50 chance of getting it coverd. best of luck.

NEX......i think that somthing like that would be coverd. i could be wrong. why are people fo afraid to tear motros apart???? anyway i would sent it in you have a 50/50 chance of it getting coverd. and they will deffanitly find whats wrong. best of luck.