Carb Float Bowl Breather/Overflow

Jacques Foucher wrote:

"A" is the adjustment tab

Thanks Jacques - got that bit.

Your diagram does not correspond with my carb's

Have this afternoon returned the  "float suspension brackets" back to original/factory position as per Rotax Wizard technique (as I understood it). That is i sighted/looked across the bowl seat (where the gasket goes) and levelled the brackets accordingly.

I also removed the float needle valves, inspected - they look good. Cleaned, with carby cleaner, the needle valve seat and blew out with gentle compressed air - no sigh of foreign objects/damage.

I have done as much as I can, short of putting new float bowl needles in.

Seems to me that few others have bothered to catch fuel that enters the air box - this might just be normal, despite assurances to the contrary.

OK try this ...I forgot that not all might understand my description  

If you still are having fuel leakage you can't be sure the needle seat is correct unless you check it.  Attached is from HMM manual 912/914 

The float adjustment I have shown works on all Bing.  As a note the standard practice for float carbs is parallel.  (Bing, Mikuni, Dellorto...and so on)  If working with an old certified Rotax 2 stroke with Tillotson it is level with the casting surface.  All easier to remember than distances in my view. 

Cheers

Thanks RW,

I printed out the same pages  from the Heavy Maintenance Manual.

I don't have a pressure tester (just mouth blow) may have to purchase one. On previous inspection/check, activated boost pump and found positive fuel shut off.

Get a cheap one from Amazon for bleeding brakes.  They work well.  Slightly more money and you can get one that has vacuum also.  

Cheers

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After trying everything I could think of, to stop the small persistent fuel leak and all the suggestions from the Forum, I bit the bullet & sent my carby's to my national Rotax agent for an inspection.

Reminder: Rotax 912ULS, purchased new 2019, first started November 2022, first flown January 2023, now has 50 engine hrs.

These are the photo's of my float valve seats, taken with a borescope camera (mechanic described them as "porous"):