very rough running 912uls

[Slyfox]

31129It's time to share what happened to me last saturday when I went for a flight in my kitfox. This airplane has the 912uls. Over the summer I've had multiple problems, one of them was carburation. I ended up putting a used carb on the 1-3 cylinder side. It has been flying flawlessly now for a couple months. Well saturday I took off and flew south east and was going to fly a low approach over an airfield about 5 miles south of felts field. I went and pulled the throttle and as soon as I did the engine started running real bad, like I had lost a cylinder. I put it to full power and was able to limp it to the runway and land without any trouble. powered up to get off the runway and it would pull itself. felt very fortunate. I had to borrow a friends trailer and haul it back to the airport. I then went and pulled the spark plugs and found no. 1 plug was white as can be, all other nice and tan. I pulled over the prop and all cylinder were equal. I than pulled the valve covers off the two right cylinders and found all valve stroking equally. I felt it was running super lean, so I removed the carburator for 1-3 and this morning pulled off the top, what I found was the main jet needle had broken at the clip. the needle was jammed down in the jet. So rebuild of this carb and all should be good again. I have heard if the clip wears into the needle this can happen. take care

[Delta Whisky]

This will go in the memory bank. Thanks for sharing.

[AvDES LLC]

wow - good find! Thank you for that info.

[Av8r_Sed]

I believe there's supposed to be a tiny o-ring on the needle, who's purpose is to stop the needle rotating in the clip and subsequent wear.

This is a video of the Bing 54 addressing this issue: https://www.youtube.com/watch?v=SwSgRaulMjo

Looking at the exploded diagram on the LEAF site, it appears the 64 has the same 0-ring.

[avidflyer]

I think he said there was an o ring, but I'm wondering if it was to big and didn't stop the needle from rotating around. I had a 582 or 532 that had both needles worn about half way through when I got it. Another accident waiting to happen. It was the earlier set up before they used the o rings. JImChuk

[Slyfox]

had an o ring you can see it in the picture. My original carbs had slightly worn needles. When you do your carb overhauls it's very important to remove these needles and check that the clips fit nice and tight. If they don't replace the needle, the clip and the jet that the needle goes into. What happens is the needle likes to rotate, or spin. when that happens you get wear at the clip and at the needle. It also oblongs the jet inside. Ultimately the needle will break and lodge down in the jet thus cutting off the fuel. I rebuilt the carb and transferred all the new parts I put in the original carb, All rubber, needle and jet, and my blue floats. I ran the engine yesterday and it ran very nice, just waiting for good weather to fly now. take care

[atosrider]

blue floats, haven't heard of those yet, where can I find out more about these?

my float story, 912uls .. during an inspection I removed the fuel bowls, and it was very crowded to fit them back on .. a tiny chip of black float material ended up in the bowl .. that little chip was able to momentarily block fuel flow, the missing beat of the motor shook the chip out of the way ...

the black floats are brittle .... 2006 parts, flying since 2007, probably happened around 300 hours .... maybe the floats are different now

[Slyfox]

https://msacarbs.com/product/rotax-bing-blue-epoxy-float-ms80-430/

[napierm]

Any statement as to how well these floats hold up to ethanol?

[Slyfox]

been working for me