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ricklach
Joined: 20 Jun 2006 Posts: 127 Location: Kernville, Calif.
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Posted: Tue Jun 01, 2010 7:30 pm Post subject: 912ULS Carberator Dirt Problem |
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Annual Safety Inspections have again proven VERY worth whiled. It was time to pull the carbs off my 912ULS and give them a good cleaning and replace the mounting sockets.
But before that some background information. I fly here in California off my own dirt strip at home and spend half of my time going into dirt back country strips. The engine has run flawless with only a couple of carb synchronizations needed. It has never ran poorly, lost power or shown any problems, other than an idle problem which the synchronization took care of.
Now back to the fun. During the initial disassembly every thing looked just fine. Very little dirt no leaking and no noticeable ware anywhere. Then I took the Idle Jet out, I found a noticeable amount of dirt and debris around the outside of the jet. This was very alarming because the engine was idling just fine. Then I took the main jet out and so far so good, so I thought. Then I looked into the hole where the main jet came out of and noticed something black around the inside of the hole down inside. When I poked at it with a small screw driver, DIRT came out, a lot of dirt. With a little digging it just keep coming, see the first picture below. What a surprise. Now I had to figure out where this dirt came from. After some time and close inspection I figured out that ALL THAT DIRT came in through the small vent hole at the front of the carb, see second picture below. In the picture it’s the hole with the screw driver in it. Then I got kind of bothered because if all that DIRT came in through that small hole how much went in the BIG HOLE just above the small one. The Big Hole is the direct intake to the carb and the engine. The reason this is so alarming is on the 912ULS there’s not real Air Filter. It’s just a simple intake hose into the Airbox that feeds both carbs directly. My intake is on the bottom of the cowl and this must add to the problem.
So what dose all this mean? First, Annual Safety inspections really pay off. Second, DON’T ignore any item on the Rotax inspection list, and third, if your 912ULS air intake is on the bottom of your cowling with out an Air Cleaner in the system, maybe you should rethink your aircrafts intake design as I am.
Owe yes, one last thing. One of the rubber mounting sockets that mount the carbs to the intake manifold was split over two inches under the clamp where it could not be seen until removed.
Rick
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_________________ 701Driver
N35 26.700, W118 16.743 |
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Roger Lee
Joined: 10 Jan 2006 Posts: 1464 Location: Tucson, Az.
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Posted: Tue Jun 01, 2010 9:10 pm Post subject: Re: 912ULS Carberator Dirt Problem |
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Hi Rick,
You really need to get an air filter on your engine. I'm sure you can see why now. Depending on the air intake setup I would recommend either two K&N's or one larger K&N Carbs need to be balanced every 100 hrs. or the annual. Rubber parts like the carb socket or rubber hoses have a 5 year replacement on them. I see back the picture this engine has a few years on it. The black electric starter. The new gold colored starter is a higher torque starter and you would benefit form it. I would recommend that starter, too. One problem is some of that dirt has gone into your engine and is doing not so good things. If it was me I would change the oil and oil filter, then do a purge to help flush as many dirt particle out that may be possible. Those carbs need to have every orifice cleaned with something like a jet spray of carb cleaner. Soaking them first will help loosen all the dirt and it will come out much easier. That carb socket looks old enough to be of the old style that did not have the 8mm spacer in the retaining band. That means the carb socket was over tightened and that will cause this split. Be careful about using tools to dig dirt out so has not to cause burs on the metal inside the orifices or enlarging any holes.
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_________________ Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
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