Dave trimmer

My muffler is being blown off by back pressure, is it ok to solder the 2 pieces together, see hear at http://www.julton.net/FZ120.htm

Thanks, dave trimmer

bigtim

My Feedback: (13)

no! do not solder the pipes together.
dave I seriously doubt the back pressure is blowing your muffler off, its probably not tight enough.
there should be a locking nut at each end of the pipe that connects the actual muffler to the engine they need to be pretty tight,not so tight that your breaking any thing but pretty snug.
after a few runs any fuel residue that leaks out through the gaps will burn and seal any leaks that are there.
you need to screw the pipes together as much as possable then tighten the lock nuts with a wrench on both parts,the muffler,and the nut.the photo of the engine clearly shows a space for a wrench on the muffler and the lock nut.
like any 4st engine there is some vibration so nuts,and bolts need to be tight,along with engine mounts etc...

Dave trimmer

the problem is there isn't a bolt or nut going through the muffler, it snaps on but once i put my 120 4 sroke up to full power it just pops off.

RCKen

My Feedback: (9)

Dave,
What do you mean "snaps on"? The muffler is threaded and you should be screwing the muffler on to the short pipe that comes out of the had of the engine. Also, on each end of that short pipe should be a lock nut. This is simply a nut that you should screw all the way onto the pipe. Then screw the pipe into the engine and get it in the position you want it, and back the lock nut out to where it contacts the head of the engine and tighten it down. The same on the muffler end of this pipe. Screw the muffler onto the pipe and then back the lock nut down to the muffler, and tighten it down. These lock nuts will keep the muffler and the short pipe from vibrating loose while the engine is running.

From what you say about the muffler "snapping on" it sounds like the threads inside of the muffler have been stripped out. If this is the case then you will have to replace the muffler.

Ken

bigtim

My Feedback: (13)

there should only be 4 parts to the typ. 4st muffler.
the actual muffler.
the pipe that connects the muffler to the engine.
and 2 locking nuts that screw on to each end of the pipe.
thats it, the YS doesn't have a pressure fitting because its pumped,the manual doesn't cover it not sure why?

so without seing a picture of what you are talking about,here is what you should do.
this take the 4 muffler parts and lay them out in front of you first pick up the small connector pipe and screw the locking nuts on each end as far as they will go,then screw this assembly into your engine.
then take the muffler and screw this into the pipe also as far as it goes,holding the muffler with your hand tighten the lock nut at the engine side tightly in the position that works for your plane.
then use a wrench to hold the muffler, and with a second wrench tighten the lock nut on that side.
it should be as simple as that. its taken me longer to type this than for you to do it.
well put Ken.
if any of the threads are stripped then the parts need to be replaced the thread pattern is very fine and care is needed when screwing the parts together

acarter

duct tape fixes all problems

horace315

My Feedback: (15)

i have always had problems with the 4 stroke muffler jam nuts coming loose,like was said here vibration loosens them up.i have added extra locking nuts to all of my 4 stroke mufflers and that has solved the problem for me.

Dave trimmer

As you can see there are no bolts or lock nuts, and that rim in the one photo is NOT a thread but a rim to stop me from closing the muffler too far.

Please help me, thanks, dave trimmer

aerowoof

i'd drill one or two small holes thru into that lip and use some small sheet metal screws to keep it together

RCKen

My Feedback: (9)

Dave,
Thanks for the pictures. You have a broken muffler. Those two halves on a YS muffler are usually welded together. Short of having those welded together I would recommend that you try using JB weld to hold the two halves together. If that doesn't hold it then you'll need to get a new muffler for your engine.

Ken

Warbird Joe

what about a hammer and duct tape. that fixes everything...

Dave trimmer

Doh! I hope it sticks!!!!!!!!!Thanks ken I'll do it before bed tonight

RCKen

My Feedback: (9)

Dave,
As I read through the other posts Aerowoof's would help. Put 2 or 3 small screws there the muffler, and then JB weld it in place. That should keep it secured.

Ken

CGRetired

My Feedback: (1)

What is the cost of a replacement muffler? How new is the engine? I guess a more important question is... are there replacement mufflers available (knowing the back-order that has existed for the YS 1.20, maybe the screws/jb-weld is the trick).

Make sure you clean up the muffler real good before applying the JB Weld. Soak it in 90% isopropol alcohol (rubbing alcohol) then scrub it clean of any oil residue and let it air dry for about a half hour before applying the JB Weld.

DS.

carrellh

If you know someone with a TIG welder, and knows how to weld aluminum, you can have it fixed forever.

CGRetired

My Feedback: (1)

Oh yeah... that will work...

jetmech05

I recommend silver solder, quick easy and lasts forever. plus you can do it yourself

aerowoof

don't think you can silver solder aluminum.there are aluminum soldering rods available that you use a propane torch to heat to around 800 degrees after cleaning eith a stainless brush.

Dave trimmer

I'll use some jb weld and pins to keep it in place. I don't have a TIB welder.

Thanks, DT

bigtim

My Feedback: (13)

Carellh has the best idea,welding alum. is a art.a TIG welder is a special type of machine for welding somone who repairs aluminum parts would have one.
without a photo of what you were talking about there was alot of missunderstanding about what you were asking, the link you provided was for the new YS engine, with the new style muffler, with jamb nuts, and a screw on muffler hence the confusion.if you have a small tap drill a couple of holes in the lip and thread some small machine screws in there.
the JB weld says its good to go for aluminum, the stuff is pretty strong and rated to 600oF you might not even need screws .