southern_touch99

Hey guys and girls,


I am having a problem with my WEBRA 1.20. I bought this engine used and it ran fine for the first month or so, then I noticed that it had gotten hot enough to burn the fuel tubbing in half where the tubbing was rubbing against the exhaust (which is a pitts style muffler). I replaced the line and then began having serious problems with this. The pressure line to the exhaust was burning off causing loss of pressurization to the tank and resulting in a dead stick landing. I replaced this line with the back colored synthetic line and it has stopped burning off. My problem is that after 3 minutes of flight my motor shuts off (no spit or sputter just a dead stop within 3 sec. or so), the line is still good and the tank and plumbing is fine ( I put a saito 1.20 on the same plane/setup with no problems.) While the plane is running for its 3 minutes it screams and when I bring it in the motor is extreamly hot and has a very hot odor to it. My theory is that some kind of vapor lock is taking effect?? If so I dont know why the motor didnt used to do this and what is the cause of the high heat...?

daveopam

My Feedback: (9)

That's a tough one without being there. Can you give us a little more info? Like what size and brand of prop, and what fuel you are using. later daveo

southern_touch99

Ok...Lets see I am using a master airscrew 16-6. I am running cool power omega 15 % fuel ( I run a lot of four strokes so ...) And a fox miracle plug. This is the same set up I got when I purchased the airplane from the previous crash and it ran super great for about a month, which kind of confuses me as to why it doesnt do great now (for over 3 min.)

daveopam

My Feedback: (9)

Something came to mind after my first reply this AM. The clunk line in the tank could have a hole.
Once the fuel level gets below the hole it could start sucking air. You said you tried a different engine
with no problems but every engine is different. My initial thought was it was over reving with to small of
a prop. It sounds like you are right in the range. The other things that comes to mind is a rear bearing problem.
I had and ST.90 do about the same thing. It would run fine for 3-4 minutes and then slowly get hot untill it would die. The rear bearing didn't feel bad but the black plastic on one side of the bearing was gone. It was causing
enough extra drag and heat to overheat the motor. Since you got yours used it could have sit for a while
and gotten some small rust spots on the balls in the bearing. Is the exhaust residue on the plane been getting any darker? Let us know. later daveo

southern_touch99

Sounds good, I think I am going to go ahead and open the motor up and take a look for myself. As far as the exhaust residue goes, well I dont really have a lot of it due to the way the pitts style mufflers with the heavy duty plastic turn down spouts shoots its away from the airplane. I do know that there is bad discoloration (due to heat on the muffler and some on the head.)

daveopam

My Feedback: (9)

Reason I asked is ....... if there is a problem in the motor the exhaust residue will be black. If you see black the muffler is loose or you have internal damage. Let me know what you figure out. later daveo

RJConnet

I can't say for sure about yours but if I sent my Webra 1.2 off screaming and it ran for three minutes then quit and landed smoking hot I would say it's running way too lean. Try backing your main needle out till it is not quite screaming (say 300 RPM below peak). Then hold the plane vertical, if the engine picks up a little RPM but does not sag you are probably OK. You might also try a little less nitro, the Webra will run fine on 5% also you might add several ounces of castor oil to the mix.

RJ

southern_touch99

I have tried this, and my theory on two strokes are that you lean them until they are at the max and can still run in a vertical position. I have tried to richen it and it makes it slobbery and not powerfull at all (it begins to load up during flight). I will try the lesser nitro gas but its still weird that it didnt do this before. I am seriously considering an upgrade to the MVVS 1.5 or maybe even a 3W-24?? I like an engine that can give optimal performance and if the webra cant do this for me then it will be for sale.

Quote
<hr>If its not busted then your not challenging yourself<hr>

derby

I would'nt be too quick to give up on the Webra they are a very well built motor that gives excellent performance to weight. First off the Webra glow motor runs on 5% nitro. Next, often the motor will run odd if it has been lean for some time. I would start by turning the low speed mix to factory spec, 1.5 turns out, then start the motor with a new glow plug. I say to use a new plug because the lean run has more than likely burned up the last plug and now requires the extreme heat to enable the motor to run at a good RPM. Start with the high speed needle valve out real rich and start motor slowly turn high speed in til RPM is peaking, a tackometer is real helpful. Then once you can no longer gain rpm by turning needle valve in back it out so you drop a couple hundred rpm. The plane should leave a nice trail of smoke when the motor is running max rpm. The next challenge is to set the low end and this requires some patience. turn only 1/8 of a turn at a time til the motor doesn't lose rpm or girgle when changing over to high rpm. Keep in mind that the low end can load up if too rich and you think the high end needs adjusting. This will cause the motor to run lean and give you a 3 minute run and get smoking hot. I'm possative that a little time spent tweeking th carb will result in one happy flier. Take it from me as I also experienced a simular problem with my webra. I will only buy webra's now that I can tune them.

Good luck [img]i/expressions/face-icon-small-smile.gif[/img]

southern_touch99

Well, I tried the 5 % ( I dont like having to buy different fuel for one motor but I did it anyway ->,most everything else I have is 4 stroke). I have tuned on this thing until I am blue in the face and I think its time to put a Satio 1.80 on there, I have never been really happy with the torque the webra offered (though it ran real strong when it use to run). If anybody wants a Webra 1.20, I will make you a good deal on it [img]i/expressions/face-icon-small-smile.gif[/img]

choo choo

Hi
You need a new piston, new sleeve,new bearings and maybe a new crank because you have burned that one up with excessive heat and not enough Lube.
Have a good day
Choo Choo