i put a new os 46 fx on on of my morris top cap's and it run's well until you throttle up, it has massive chatter. kinds of sounds like detination. ive raised and lowered the head and it don't seem to matter. the only thing i can think of is fuel. im running 15/20 nitro and oil. any one else had similar problems with this motor.

Mine did that too untill I changed props................John

Check your engine mount bolts... Maybe a head poped off..... What prop are you running?

Some planes resonate at certain motor speeds (frequencies) especially if the motor is bolted directly to the frame like in the profile bodies.

Usually doesn't hurt anything and sounds worse than it is.

If this is the problem try changing props, adding some rubber between the engine and wood. It may go away on its own as the engine breaks in, that's what happened on my Morris Knife (not sure why).

the first prop i had on the plane was a M/A 10X6, now it has REV-UP 11X4 with a little rework for rpm. i also put a KB1L HD plug and it did'nt help.

the sound wont bother me but the rod sticking through the side of the crank might cause me to have a beer.

You might try a little more prop... Maybe a 11x5 x 4 apc or a 12 x 4 apc.....

Check your connecting rod. I had a magnum that did what you are describing. If either the lower bushing or upper conection to the piston is loose, it will sound awfull and vibrate quite a lot. misballanced props don't make a sound that can be confused with detonation, but a loose con rod will sound exactly like it.

I surely wouldnt run a 10-6 on it.............John

Put in an O.S.

Try an O.S.# 8 GLOW PLUG

the plug it had was an OS 8. i checked the rod and it has .003 which is ok. i raised the head another .005 and the noise is almost gone, only a little in the mid range. i also changed the prop to a M/A 10X7 3 blade, it don't spool as fast but it's a lot quieter. RR

Dude, is that a tri-blade? The whole point of this plane is the x4 part of the prop. Slow and thrusty is what your going to need. Your plane might start doing the fish dance if you forget you have a 10x7 on there. Run out and get a 12x4 or 12.25x3.75. Then you will have the right prop for the right plane.

the motor is lean!!!!! I bet the motor is new. You have to run os motor's real rich untill they break in. And then you have to take your time leaning it out. Dont know why that is but that's what i have found. If you break the motor in like the book say's ( 1min rich and then 1 min leaned out, back and forth for the first whole tank ) They break in fast. When you get about 2 gallons on the motor you can lean it out and get the power without the knocking. If you dont take the time to break it in, it will take twice as long to get rid of the knocking.

hope this help's

BTW put a 11x4 on it to break it in and then put a 11.5x4 or 12x4 on it after a gallon.

i know the motor is almost new i just dont know how new. one of my customer's came by my shop with a trainer and gave it to me. said they found it in a field and knew i was addicted to r/c.

if it was not broken in propperly then all is almost lost. i'll run it till it throws a rod then i'll get to have that beer.

MR HELL. your eminence :-?) i know the long low with the prop thing is the way to go but the noise was not mormal. when are we going to fly together. pro-bro style. RR

dont worry all is NOT lost. Just run it rich for a few tanks and it should be fine.

Florida is my number vacation destination so you will hear from me!

cant wait. i was in tn aound new year's. my brother live's in blane tn, about an hour from knoxville. 392 off of 40 about 20 miles north. maybe this summer on my next road trip.

A customer found it in a field, gave it to you and you are flying it?

Whatever happened to calling the police and reporting that someone found a trainer? It could have been a fly away or someone may have stolen it.

If you did all of that, I apologize.

CALL THE POLICE. at the risk of sounding ............. the ama requires all pilots to put there address and other information in your plane. had this person been in compliance he/she would have there plane as we speak and my top cap would have a different motor.

in south florida if you get burgeled and no one is hurt when you call the police they send a rent-a-cop who gives you a case # so it seem's they care.

the plane went to a pilot who was down on his luck with his last trainer and needed an air frame.

i would have donated the whole thing to my club for a club trainer but the last one i donated " hobbico 60 w/ os61sf rtf" flew away while not being used as promised.

it was a nice thought though. RR

reason for edit
the plane also had crash damage, bruised wing and a broken stab. when they droped it off i checked it for a name then for why it flew away. the positive going to the battery was pulled out a little, just enough to not make contact. i think it was trimmed real well because the tank was empty, so it kept going up until it ran out of fuel then glided for a while.

the person who i got it from works for dade co. public works dept. which explanes why he was tromping through feilds.

I've heard that knocking / rattling sound from Moki 210's and the new big MDS 218 all the way to O.S. 160's. They weren't lean or new, and I think it was some engine noise resonating from the airframe. It sounds terrible and I wish I knew exactly what caused it! If you guys know what causes it, please let me know. I've heard others complaining about it too.