Re: Zenoah G-38 High Speed Valve Setting

Jul 06, 2004 1 Replies

Sometimes it pays to follow the instructions. What had been thought by some as being a typo in the instructions, myself included, i.e. the high speed needle with 0-1/4 rotation, turned out to be right on the money. After doing a search on RC Universe I found the following gem of a post:


--------------------------------------------------------------------------



------ The old G38 carb (WTA6) is designed to be run with the high speed needle adjusted from closed to 1/4 turn open...There's a small brass plug over the high speed needle with a small hole in the center..With the needle closed there is still enough fuel going through the hole...



So most of the experts were wrong for this carburetor and they were giving out information for the newer carburetor for the G-38 that does not have the brass plug.



Here are the results I obtained using a 3W 18-8 prop with low speed needle set at 1-1/4 turns open 2000 rpm, high speed needle set at 1/4 turn open 7800 rpm. The engine started right away after choking and going to 1/4 throttle. The transition was excellent after a slight warm-up and the idle was good and top end perfect. I emptied a tank transitioning from high to low several times. After cool-down I started the engine several times using the pre-sets and the engine started easily. The winds were blowing ~ 30 mph today so I will try her in the air tomorrow.



Joe L.


The hole was a modification to prevent the user from over leaning the high end. On some engines it also keeps them from being leaned enough to run correctly. The fix is to Peen the hole closed and then open the High end screw 1 1/2 turns and tune from their. I read this fix in one of the R/C Magazines. Terry

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required