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tuning out high idle hang

Posted: Tue Apr 08, 2014 4:27 am
by r3tro74
I've been tuning on a nitro rc truck (HPI Savage X 4.6). These are mini 2 strokes with a glow plug and have low speed and high speed needles- LSN & HSN, turning out gives more fuel. I came across this write up and it reminded me of posts on here where people were sorting out a high idle hang up. I thought it might be useful to us here to help figure out witch circuit is causing this problem.
http://www.extremercmods.com/content/tuning-popup.html" onclick="window.open(this.href);return false;

Re: tuning out high idle hang

Posted: Thu Apr 10, 2014 7:24 am
by Vintageman
Even though RC carb may have less jetting circuits to cover closed to WOT versus say a VM Mikuni carb there are a lot of similarities here.

Main too rich. If you run WOT and then back off a little (not full close as RC) and engine stumbles, gurgles, and then straightens out main too rich (read that somewhere on Mikuni carb tuning or something.) I have found this to work well as a test.

Running too lean or high RPM idle. Well first is an air leak. Interesting about temp drop. I suppose true on exhaust temp. head temp too if you don't set still too long. Here's one mans idea about such a topic ->
https://www.youtube.com/watch?v=DKKudxE1wGA" onclick="window.open(this.href);return false;

Oh yes RC engines are fusy little buggers, don't have them anymore, fun stuff . Now this one is tuned->
https://www.youtube.com/watch?v=_vmF7stnNyg" onclick="window.open(this.href);return false;