RCU Forums - View Single Post - Sachs 4.2 Carb Issue
View Single Post
Old 01-04-2011 | 05:31 PM
  #23  
speedracerntrixie's Avatar
speedracerntrixie
My Feedback: (29)
 
Joined: Jun 2010
Posts: 9,704
Received 200 Likes on 172 Posts
From: Happy Valley, Oregon
Default RE: Sachs 4.2 Carb Issue


ORIGINAL: Tired Old Man

Absolutely.

The carb needles are set much too rich for the engine to idle down properly. The initial settings should have been 1.5 for both needles, and depending on your elevation, ended up somewhere close to 1 on the low and 1.25 on the high. That's a rough estimate but 3 turns for both is unheard of. You'd need to be flying well below sea level for that to work out right.

The shut off is another story. Either the throttle linkage is of an incorrect length, a very common problem, or the end points were not set up to permit the throttle plate to close completely, or both. Of course there's the possibility that the low idle set screw was left on the carb, limiting it's ability to be shut down from the transmitter. The low idle set screw is a large fat one that just sits there and is normally used for setting the idle on yard equipment. Usually it's completely removed for RC use.

Bending both ends of the needle carriage is normally a no-no. Only one end is adjusted. This may be why you ended up 3 turns out.

Remember, he is running glow fuel not gas, with glow you need to run more through the engine. This is where the additional power comes from.