Stay tuned for 912UL valve pictures.....

[84KF 4]

I tracked down the problem of a lowno compression cylinder to the intake valve and seat. With the intake manifold off you could see the air bubbles when on the compression stroke. Looks totally gummed andor carbon'd over. (top side, not the face)

Exhaust side look perfect, and clean.

  I have taken the cylinder head off and valve out and am in the process of cleaning and resurfacing.

  Pictures soon to follow. Check back soon.

It will be more interesting then TCP and fiberglass.

steve

[eskflyer 1]

Steve

Out of curiosity how many hours do you have on the 912. And what fuel do you burn?. I will not ask if you use TCP, lmfao.

[84KF 4]

That's just it....   about 55 hrs TT since new.

The previous owner had put about 35 hrs TT on it, and it ran great when I got it. When you pulled the prop thru by hand it had excellent compression. You could "feel" each cylinder 'pop" as it went through it's strokes.

I have only used Shell V-Power(the 'premium) auto gas and Mobile 1 full synthetic oil. That will change now, but to what I haven't decided.

A visual check of the valve and seat, now that they are clean, shows them to be in excellent shape, with no warping, chips, or scratches. I guess the real test will be after it is back on the cylinder.

There is one more that needs attention also, but after seeing this one, I might just try a strong dose of Marvel Mystry Oil in the fuel before I pull that one.

The heads affected are both the rear. Front ones feel fine.

Attached are the pictures...not a pretty sight.

steve

[eskflyer 1]

Looks like the same crap that was in your tank just blacker LOL .

Take care fly safe

[84KF 4]

The head went back on just fine and the pull through compression is now strong and tight. I get the repaired muffler back Monday.

I like the Rotax use of rubber seals and o-rings. No need to have a new gasket on hand for rocker covers, etc...

steve

[akflyer 1427]

damn.. looks like the valves have been 150,000 miles not 55 hrs..

Did you threaten Rotax to place the broken muffler in places it should never go if it breaks again?? 

[84KF 4]

The muffler was brand new from Skystar (Kitfox). Apparently the "new and improved" product has the same inherent weakness that the older ones have...as you still have to install your own brace from the stinger pipe to the body of the muffler. This is not part of the $375.00 muffler, and this information was not passed on to me by Skystar at the time of purchase.

  I guess this is the name of the game in experimental "stuff", but when a product fails repeatedly in the "real" world, the manufacturer will re-design its product so as to eliminate the problem... not offer a supposedly "fixed" product, that still requires the same old quick fix.

Oh well..live and learn.

  The only option I received from Skystar was to "Send the muffler back to us and we will take a look at it for repair…" (that was the entire reply)

I weighed the cost of shipping it back, then the cost of the actual repair..., after it would be determined that it was "my" fault, then the cost of return shipping and decided to have it repaired locally for $40.00