About to rebuild my carbs

[Dorsal]

The engine is 17 years since new, 7 years in service, 500 flight hours so it seems like a good time to replace all the rubber bits in the carbs (did so on the rest of the engine a year or two ago). Filing, removing then re-peening the butterfly screws seems the only slightly tricky part. Would appreciate any tips from those who have done it.

[Av8r3400]

"If it ain't broke, don't fix it."

Are you having an issue that needs to be rectified?

[Dorsal]

Nope, and I generally adhere to that principal but it did seem time for a thorough inspection/cleaning and while I am at it replacing the o-rings and diaphragms.

[Russell320]

Rotax-Owner.com has a great video on carb rebuilds. Watch the video, read the manual and have fun.....it's not too difficult. Oh.....and order your parts ahead of time.

Russ

[Dorsal]

Have, did and about to :)
The basic parts came in last week and it is no day for flying today.

[Dorsal]

disassembly went mostly as advertised including damaging the main needle fixation screw :mad: looks like I will leave that part assembled.

[Av8r3400]

Fin - If you are doing an ultra-sonic cleaning of the bodies of the carbs (standard procedure) do not forget that the ball-bearing blocked passages will need to be re-epoxied in order to prevent air leaks.

This is a commonly overlooked item which causes poor running after a rebuild.

[Dorsal]

Thanks for the heads up, not doing ultra-sonic at this time as everything looks quite clean (no build up). I am assuming you are referring to the material on the body of the carb covering these passages? some of that flaked off so I was wondering what to replace it with?

[Av8r3400]

Unofficially, any fuel proof epoxy will work. (JBWeld)

Another piece of advise, if your floats weigh fine, DO NOT REPLACE THEM. Seriously, if they ain't broke don't replace them!

[HighWing]

This is ancient history, but my tendency now would go with the ain't broke advice - with the exception of the diaphragm and other more fragile parts. When I did my overhaul in the old days, the first attempt at a test flight resulted in a very rough running engine with fuel all over the place below the vent tubes. I learned that they had sent another needle version that didn't stop fuel flow into the already "full" float bowls. I replaced with the old needles.and put another 600 hours on the airplane. A note on ultrasonic cleaning. What is being used as the fluid in the ultrasonic bath. The reason I ask is that there are numerous chemicals that can be used that would not harm epoxy but would loosen sediments for rinsing. Is the fluid prescribed by Rotax?

[Dorsal]

Thanks for the JBweld advice, I also weighed the floats and they are fine. The only parts I replaced were O-rings and the diaphragm. They are all back together, the throttle action is noticeably smoother, the 0-ring was sticky and gunked up. Hopefully in the plane next weekend.

[Av8r3400]

Lowell, plain water will remove/loosen the epoxy in a heated ultrasonic cleaner. I usually use water with a couple drops of dawn dish soap.

[tommg13780]

Mr Fin,

Good decision to do your own carb work. I made the mistake of sending my carbs, that were working fine, to a "leading" vendor. The estimated cost was $500, actual came in at over $1,100. The most aggravating part was the fact that they returned home with 3 of the 4 floats defective. Then the next insult was refusal by means of ignoring me to at least replace the defective floats. This was happening simultaneous with the first defective float crisis. I know this is not typical and for those of you who want to make excuses I will agree in advance that it's probably the way I packed them for shipping which caused the faulty workmanship.

Another solution is new carbs from an ebay seller that has pairs from time to time at $350 NIB with throttle sensor for turbo on one of the units.
Where they originated from I have no idea but that's what I've been flying for the last 60 hours trouble free.

By the way I remember your exceptionally nice Kitfox from the Northeast Regional Flyin hosted by Chris Engler.

[Dorsal]

Sorry to hear of the troubles, sounds like you got quite a deal on new ones! I just have to touch up a few sealed ports and I think I am good to go. We should piggyback on an existing flyin (hosting our own was too complicated).

[airlina]

Sorry to hear of the troubles, sounds like you got quite a deal on new ones! I just have to touch up a few sealed ports and I think I am good to go. We should piggyback on an existing flyin (hosting our own was too complicated).

Sounds like a plan Finn, lets keep an eye out for a centrally located flyin this summer. would be good to see a bunch of Noreasters again. Bruce N199CL

[tommg13780]

N23, Sidney, NY 3900' paved and good well maintained turf. Flyin breakfast usually 1st Sunday in June. Airport has loaner vehicle for pilots.

[Dorsal]

Sounds like a winner :)