Bayer-Z28

I was running the truck today, runs good, but slightly rich (Could be from the full tank) I notice after I run it at all, the idle stays pretty high and takes it a minute of sitting to come back down. I set the throttle opening to 1mm and tried tuning to compensate for it. It didn'tlike it so I opened the throttle a HAIR to get it to idle. But once it's warm, the idle stays high. Even if I have sufficent smoke at take off from a dead stop, could the LSN still be set too lean? I've been catching some videos on Youtube abotu how to tune (HPI Vids) and mentioned that if the LSN is set too lean, the engine speed may rise at idle. ??? Possible? I'll mess with it again tomorrow afternoon.

I've also got a low end bog I was wondering about. I'll try and get a video this week. Maybe the lag from the 2 stroke to get into the powerband?

rclugnut10

My Feedback: (1)

it sounds like you got a rich HSN and a lean LSN, richen up your LSN and then get up to more speed and lean out your HSN, you're not gunna be able to get great low end if your chocking it at the top with the way these carbs are setup

the lug

Argess

An idle can be high for a number of reasons, but if hangs high for a few seconds and then goes low, it is usually the HSN is too lean. If it stays high, or even climbs, then the LSN is too lean.. If it stays high for a very long time, and then slowly comes down, both the HSN and the LSN may be too lean.

What happens, is that after a WOT run with a lean HSN, the engine idles down with no residual fuel in the crankcase. The engine idles high on a lean mixture, but after a while, it will settle down to the LSN mixture....IF the LSN is adjusted more or less OK. If the LSN was too lean, it won't settle down. The fact the idle finally drops is a good indication the LSN is rich enough.

Here's a video of a mild case of your trouble. The "High Speed Too Lean" banner starts around 0.55 seconds into the video. Start paying close attention around the 1:00 minute mark. Notice he drops the throttle around 1:07, the idle stays high, then it drops to a normal idle at 1:10

http://www.youtube.com/watch?v=BJFsJ...eature=related

So...start by richening your HSN about 1/4 of a turn. If you have to richen the HSN to the point that your high rpm performance starts to suffer (from being too rich), then go ahead and richen the LSN.

The twe work together, so a little back and forth tuning is usually necessary.

ps: there has been argument on this subject before. In that case, the OP went with the majority of "helpful" contributors and merely richened the LSN. That did make his symptoms go away. He was back a week later asking why he kept burning up glow-plugs.

Bayer-Z28

^ I was gonna just start back from flush needles.  I had it tuned fine for the cold, but it's been in the 50's and I put a new pipe on.  My problem originally was that I started tuning the LSN first instead of the HSN.  Oh well, live and learn.  I'm gonna mess with it more this afternoon.

Thanx guys.

BudBud

Always start with the HSN as it does also affect the LSN. Once you get the relationship pretty close, the LSN very seldom needs much adjustment. The tune can vary daily with humidity, elevation and temperature, so do not be surpised if one day it screams, the next day it suffers. They are the most sensitive engines in relationship to running conditions that I have ever experienced. Here in Kansas in the summer time, our temperatures drop dramatically in the evenings and the humdity usually climbs. I can have one running perfect as as it gets closer to dark, the thing may need to be tuned every 15 minutes. It does not usually take much once you get close. That is one reason I always recommend those tuning videos to guys with little experience, so they know what to listen for. A lot of guys say go back to flush and tune again, I really do not see much sense in doing that, it is just a lot of wear on your needle o-rings. Glen