Zenoah G-38 High Speed Needle Valve Setting

If I recall my G-38, that's correct, especially for the 18" prop. That's a not a big load for that engine.

Dr.1 Driver "There's a Hun in the sun!"

My experience says to have the hi-speed needle at 1 1/4 turns open...not 1/4. Mitch

0~1/4 turn for the high end and 1-1/4 rotation for the low end. The low end idle seems about right but is that a typo in the manual for the high end? All the experts in the club said that I should start at 2 turns open for the high end but this seems extremely rich even though the engine started fairly easily when I started it there. The 0-1/4 turn would seem way too lean. I'm using a Zinger 18/ 6-10 prop which seems to be adequate power for for this engine. My only other experience with the larger gas engines is with a Fox (Sachs) 41cc engine which has run fabulously out of the box with no fiddling with the needle valves. So any suggestions are welcome at this point before all my brown hair turns gray. Joe L. =========================

According to Horizon's site, you're a bit under-propped. Here's the product info link:

G-38 is the ideal gas engine for models such as the Midwest Extra 300S, Cap 232 and Super Stinker, as well as the Lanier Cap 232 and Stinger 120, where sport performance is desired. It is also a popular choice for many scale projects. It will turn an 18 x 10 prop at 7100 to 7400 rpm.

The manual you have must contain a misprint. Here's a direct link to the current one:

On page 6 of 24:

1. Standard settings of each needle is as follows: a. Low-Speed Needle: 1-1/8 plus/minus 1/4 b. High-Speed Needle: 1-3/8 plus/minus 1/4

Prop chart page 12 of 24 G26A 16x8 @ 8,700 G38 Gas 18x10 @ 7,300 G45 Gas 20x10 @ 7,200 G62 Gas 22x10 @ 7,200 GT80 Gas 22x12 @ 7,200 24x10 @ 7,200

0~1/4 turn for the high end and 1-1/4 rotation for the low end. The low end idle seems about right but is that a typo in the manual for the high end? All the experts in the club said that I should start at 2 turns open for the high end but this seems extremely rich even though the engine started fairly easily when I started it there. The 0-1/4 turn would seem way too lean. I'm using a Zinger 18/ 6-10 prop which seems to be adequate power for for this engine. My only other experience with the larger gas engines is with a Fox (Sachs) 41cc engine which has run fabulously out of the box with no fiddling with the needle valves. So any suggestions are welcome at this point before all my brown hair turns gray. Joe L. =========================

According to Horizon's site, you're a bit under-propped. Here's the product info link:

G-38 is the ideal gas engine for models such as the Midwest Extra 300S, Cap 232 and Super Stinker, as well as the Lanier Cap 232 and Stinger 120, where sport performance is desired. It is also a popular choice for many scale projects. It will turn an 18 x 10 prop at 7100 to 7400 rpm.

The manual you have must contain a misprint. Here's a direct link to the current one:

On page 6 of 24:

1. Standard settings of each needle is as follows: a. Low-Speed Needle: 1-1/8 plus/minus 1/4 b. High-Speed Needle: 1-3/8 plus/minus 1/4

Prop chart page 12 of 24 G26A 16x8 @ 8,700 G38 Gas 18x10 @ 7,300 G45 Gas 20x10 @ 7,200 G62 Gas 22x10 @ 7,200 GT80 Gas 22x12 @ 7,200 24x10 @ 7,200

If you are having trouble setting the high speed needle you should get with someone that has experience. It is very difficult to explain how to do it in words. You must be able to "hear" the engine, and know what it's supposed to do. I've never heard of, nor seen, a needle that is only open 1/4 turn for a correct mixture. I always start with 1 1/2 -2 turns out and go from there. It has always worked for me on any kind of 2 stroke gasser. I've seen a lot of them in 49 years. good luck. Eddie Fulmer

Right this only happens with the Zenoa 38 not the 26 or 45 or any other

to get the top end on song play with the BOTTOM JET yes the BOTTEM jet it's all to do with gas flow

with a metz 19*8 wood on standerd carb and exserust you will get 7600 rpm top jet 3/4 out bottom 3/4 out. if the rpm drops after 1 min rithch the top jet a little (to week getting hot) the Bottom jet affect the top end it's the only engine that does if you have a home made silencer on it well i hope you know what your doing as the 38 is very fussy. The 38 like's being loaded what RPM you get from a 18*8 might be the same as a 20*8 it's a sloger engine not a rev engine the power is a 9000 rpm not 12000 rpm it's a nice engine you jsut need to know how to work it