FOX Burp

[Phil Coopy]

Fell into something today.  I have had a bad "burp" on my FOX35 powered Ringmaster. So I tried the trick of putting a wooden insert in the transfer port some time back..but it didn't improve. This week I tried it again....nothing.  Yesterday I tried the trick again but this time instead of aligning the stick in the center of the port I shoved it all the way towards the front edge of the port.......voila...made all the difference in the world...works great!  I'm not claiming that I made any great discovery here but I thought I would just share my experience and maybe someone other than me can explain.  As they say, "I don't know all I understand about this".

Phil

[Paul Taylor]

Phil,
Did you do it like this:
http://stunthanger.com/smf/index.php?topic=3878.0

DennisV sent me this pictures some time ago via email. I had a Fox that burped so bad that it almost sounded like it would quit and restart at times. A real butt clincher.
Cured my problem first try.

Paul

[Jim Kraft]

Phil; You may be onto something here. I have done several with JB weld in the center of the bypass, and they have worked OK for the most part. But on some planes they still go very rich in certain places. They don't burp like they use to, but I would like to try your way just to see. By the way, what plug are you running?

[Bill Little]

Hi Phil,

All of the "VooDoo" surrounding our hobby is not always confined to a certain Goldberg kit combat plane! LOL!!

If it works, it works........ and it is good!

Bill <><

[Bob Reeves]

Hi Phil,

All of the "VooDoo" surrounding our hobby is not always confined to a certain Goldberg kit combat plane! LOL!!

If it works, it works........ and it is good!

Bill <><

Boy isn't that the truth 

[Phil Coopy]

Paul,  I used a plug the same size as it shows in your link but in the 6.jpg pic it is shown in the center of the port and my improvement came when I moved it all the way forward against theforward side of the port (had to bevel it a bit to get a good fit).

Jim, after trying lotsa plug heat ranges I just went back to a Fox Std long.

Phil

[Paul Taylor]

Hey Phil,
In the one picture it shows the plug in the center of the bypass. Then the next to pics looks like the plug was moved to the front side of the bypass. I can not remember if I moved mine forward. But like I said it ran better after the plug was installed.

Paul

[Jim Kraft]

You must be on to something Phil! If you can run without a burp on a Fox standard long plug on a profile, You have done good. I don't think mine even with the center plugged off will run without a burp with that plug.

[Bill Little]

Well, the "Fox Burp" can be a puzzling thing.  Over the years, I have seen stock Fox 35s that would burp and others that didn't.  I have even seen a stock Fox 35 burp on a Dolphin (inverted engine)!  To the point that I thought the engine would die at any time, but the pilot pulled off about a 500 point flight at Brodak anyway.............  doesn't seem to be much rhyme or reason.............