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Old Apr 01, 2007, 02:35 PM
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Nova Scotia
Joined Feb 2005
15 Posts
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Zenoah G-38 Tuning/Run Trouble

I have a G38 with little run time on it. It will hand start after 10-12 flips and only stay running for 30 - 45 seconds. It will start to die earlier and I can prolong the run time by closing and opening the choke. Also this is at less than 1/2 throttle. It doesn't like to transition beyond 1/2 throttle. I have the HS at 1 1/2T and LS at 1 T. I have also tried both at 2T with the same results. When it quits the plug is dry. The only mod I have made is the installation of the easy link carb adapter. Any suggestions??
Rob
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Old Apr 01, 2007, 08:52 PM
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Joined Sep 2006
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We had simliar problem with our G38 in a Rascal 110 ARF. Turned out that the carb needed rebuilt, the pump diaphragm was hard and not working properly. Now, one flip and it's running. Hope it helps.
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Old Apr 02, 2007, 05:42 AM
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Nova Scotia
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Will check this out . Thanks
Rob
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Old Apr 02, 2007, 12:29 PM
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Ya the gas engines use eather wallboro or tillison carburatiors they have built in fuel pumps and check valves in them-little flapper valves. And work buy the pressure in the crank case pressure,every time the piston goes up and down in the cyclinder it creates a positve and negitve pressure in the crank case. Useing this pressure-A pulsateing pressure thru a port to the dieafram in the carb, moves it back and forth creating the fuel pump in the carburatior with the flapper valves letting it in and sealing the fuel off from back flowing and forceing it forward to the jet to be sprayed into the venturi. Alot of time what happens is the rubberized seal gaskets that contain the flapper valves dry rot and have to be replaced.
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Old Apr 02, 2007, 01:19 PM
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Salem, Or.
Joined Jul 2006
135 Posts
I'd start by opening both needles to 2 turns, and recheck from there.
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Old Apr 02, 2007, 06:30 PM
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Nova Scotia
Joined Feb 2005
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T crafty and Athlon-DHU I believe are on the right track. I took the carb in to a friend at the small engine shop. He said it needed a carb kit bad including the diaphrams(hadn't been run in over a year). Just got it back and won't get to try it until tomorrow evening. Results later Thanks fellows
Rob
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Old Apr 06, 2007, 08:35 AM
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Nova Scotia
Joined Feb 2005
15 Posts
Lined up the carb gasket, put in a $12. carb kit(wasn't run in over a year) and the G38 is now singing like a bird. For Cold start I use 1/4" rope around the prop hub. 1st pull choke on, she pops, 2nd pull choke off, and she's away. Also is an easy hand start when warm. LS at 3/4T and HS at 1T gives 7500RPM with a 18x10 MasterAir
Thanks fellows.
Rob
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