OS .91 FX post-needle valve bubbles
 

I have this .91 FX, and when running I can see bubbles after the needle assembly that won't go away. I've changed that line, yet they still remain. The line prior to the needle coming from the tank looks okay though. This is an older engine with the banjo-ring fuel nipple type needle- it has very low time.

RE: OS .91 FX post-needle valve bubbles
 

Brad,


You should write to Bil Baxter (BAX) at the [link=http://www.rcuniverse.com/forum/forumid_133/tt.htm]OS Support forum[/link].

The older model .91FX had a heating problem, where heat from the engine would heat the metal needle assembly, which caused fuel to evaporate... Those are not air bubbles, but fuel vapors!
This could make your engine run terribly wrong!


It is rectified either by remotely mounting the needle valve assembly, or by the replacement of your current metal assembly with the new model's plastic assembly that does not transfer heat from the engine to the fuel.

I believe it is still done under warranty.

RE: OS .91 FX post-needle valve bubbles
 

Oh they'll pay for it? I just ordered all the new needle parts from Tower [:@] I got this motor a while ago. Would they still cover the parts do you think?

RE: OS .91 FX post-needle valve bubbles
 

If you ordered new needle parts just like your old banjo type needle valve assembly, you might still have the problem?

RE: OS .91 FX post-needle valve bubbles
 

No, this is the updated plastic one and new backplate/needle mount assembly. Unfortunately I had no idea OS was paying for it when I ordered. I just ordered the pieces last night.

RE: OS .91 FX post-needle valve bubbles
 

If it has an O ring on the needle valve body [ I expect it has ] try replacing that before anything more complex.

They get damaged and can harden.

RE: OS .91 FX post-needle valve bubbles
 

Yeah, but it's pretty much done this since the day it was new.