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3W 50i problem.

Old 12-24-2012, 08:44 PM
Springbok Flyer
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Default 3W 50i problem.

Hi guys,

Some years again I bought two 3W 50i motors, the one went into a Ziroli Stuka and I have just put the other in a P-51. The first has always run like dream. So the last thing I've expected was to have a problem with the second one.

On the P-51 I had to build a box for the motor to fit into as the rear carb had to go through the firewall and I did not want the carb just open into the fuselage. I fitted the same 22x10 prop I had initially used on the Stuka and started the motor in the P-51.

Because it was new I did not change the standard factory settings and left it to run rich for two two tanks (2 x 32oz), then I had the first flight. It was not getting on the step as it was flying quite slow and rich, but I finished the complete flight anyway. For the second flight I went leaner on the high needle and checked the prop RPM - only 5000. Decided to have another flight - the idle was irractic and would speed up by itself. The flight was again with a very rich running motor and landing was interesting with the idle problem - in fact I had to kill the engine on short finals to land.

Decided to check out why the motor was not reving higher than 5000. Leaned it more and it simply started dying, without gaining any rpm. Made a hole in the back of the box I had built around the carb, but still no change. Took the muffler off, still no change.

Is it possible that the air pressure around the carb needs me to add the little extension to the diaghframe plate? Should I simply try a 22x8 or 20x10 prop? Is it just new and tight?

Any suggestions - or should it become a sinker for Marlin fishing?


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Old 12-25-2012, 08:05 AM
All Day Dan
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Default RE: 3W 50i problem.

Jan, since the engine had not been in use for a while, I would recommend that you rebuild the carburetor first. The diaphragms do dry out over time. Dan.
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Old 12-28-2012, 02:18 PM
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Default RE: 3W 50i problem.

A 3W should never be used as a sinker. they are first class engines as you know from your other one!

I have a 55 US Competition version which has a side carb. On mine the carb diaphram vent is connected to the velocity stack of the carb. Worked so well that I vented my other non 3W engines the same way. There seems to be no difference with or without the cowl.
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