Home Forums Tech Talk Tuning the idle jet with EGT Reply To: Tuning the idle jet with EGT

Ray Lovestead

Sorry I lost sight of this thread Rob.  Here is Al’s response to my question about the small circuit tuning:


People have a misunderstanding for the reason the low speed number on the EGT being lower than the number on the top.  The EGT number is lower because of the greater heat and/or pressure, (the effects of the pipe) on the low speed verses the high speed.<br clear=”none” />Just like on the high speed, you want the EGT to read it’s highest when coming out of a tight turn.  If the temp goes down, you need to richen the mixture.  If it goes down further, it may be because the engine is too rich, so then you can lean it out and see what happen.  It’s a challenge I know, but it’s what you have to do.<br clear=”none” />Detonation occurs long before you can hear it, and when it occurs, it’s because of excessive heat and/or pressure.  <br clear=”none” />I have no experience with your carb, but I doubt, (a guess really) that the clip position will have much to do with the low speed.  Play with it and find out for sure.  Let me know, I always like to expand my knowledge base.<br clear=”none” />The EGT is very dependent on the ambient air conditions, you can’t just set it and forget it.  Get an air density gauge and compare it to your carb settings.  Over time I think you will see a pattern emerging between the two.  Low air density, less fuel, lower temp, and the opposite with high air density.  Engine compression is also something to keep a record of as the engine gets time on it.  Low compression will also affect EGT temps.  Low compression, low temps

"Karting Expert Since 2015"