Carb Float Bowl Breather/Overflow

Float needle brass seats can get contaminated or have the bottom seat with a tiny deformation. We need to polish, smooth and clean the sear.  It can at times be fixed. Here is a last resort repair. Get some brass polish. Cut a 1" square of cloth. Get a 6" long wood shank cuetip and break it in half. Now put the cotton tip part in a slow speed drill. Pur the 1" cloth over the cuetip cotton end. Apply some brass polish and insert it down into the float needles seat. We are going to clean and polish the brass seat. Run the drill at slow speeds. NOT full speed. Run it for about 1.5 minutes and the apply more polish and do it again. Once finished cleam the brass seat area out with some lacquer thinner. I've  done this numerous times and saved many carbs from replacement. Use the cloth over the cotton tip so the wood shank does not go through the cotton tip and possibly cause damage.

Hi Roger;

I had hoped  for more of a shock horror, response from such an unambiguous product failure.

Unfortunatly, due to the engine purchase date, despite such low hrs, I cant make a warranty claim.

I am advised by my national Rotax agent that, the valve seats in question are not considered to be a Rotax part, they are Bing. This sort of failure usually results in (your) polishing repair, where appropriate/possible OR the replacement of the whole carburettor body (crazy). My Rotax mechanic has taken the initiative to source Bing valve seats - remove the faulty ones and press in new.

It will be some time before my aircraft gets back in to the air - I will report then as to the success or not, of the repair.

Hi Sean,

I doubt you'll  find valve seat replacements  and on top of that trying to remove and install another. I learned my polishing technique from Rotax service center experts years ago. Never ruined one and have saved them all so far. You can ruin anything if done wrong. It's  rarely about muscle, but finess. When done right it really works.  You're  only trying to remove contamination and polish the bottom of the seat. You're not trying to do anything else.

If you don't fix this then an expensive carb purchase is in your future anyway.

RL,

I hope you are wrong.

My Rotax mechanic has an extortionary reputation/second to none, here in Australia  - it was his diagnose & remedy (new valve seats) not mine.

Time will tell - as I said my aircraft will not be back in the air for a month or two  - I will report back then,

Hi Sean,

If you're  going to try and replace the seats anyway why not try and polish them? If it works problem solved.