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Axial .28 Spec 1 S

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MightyMantis

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  1. Bashing
So I'm pretty new to the RC nitro scene and I'm seeing a lot of different advice on how to tune your engine. Most, if not all, tutorials and guides describe setting the HSN first and then the LSN and idle. Funny thing is that axial racing says just the opposite!

quote from http://www.axialracing.com/ftp/engines/techtips.html:
" The setting that come stock on your engine are for break-in purposes (first couple of tanks). To begin tuning for performance, the low-end and main needle will need adjustment. It's best to tune the low-end needle and idle first, then tune your main needle. Adjustments are done in tiny increments - looking at the clock, it's the range of adjustment from 12-to-1 (1 hour = 1/12th of a turn). To fine tune and make sure you get smoke on low-end (give it some throttle from a dead stop) and than thinning out as it reaches the top-end. Remember you should always see some smoke through out the full range. "

Out of all of the tutorials/guides that i've read I've never been able to understand what exactly the relation is between the HSN and the LSN especially when you have a mid range needle!!

My understanding is that the mid range needle determines where the LSN stops and HSN kicks in. Does anyone know what the proper workflow is?

My RC is a Robitronic Mantis with an Axial .28 Spec 1 S engine running on Merlin Expert 25% using the default medium glowplug.

it runs great with what i've been doing so far besides that I suppose it sounds a little "grrrrrrrrrrrrr" at half throttle, above that it has a proper sound to it. Temps are ok, at 220F.

Anyway, what are your thoughts about what axial advices?
and can someone expain how the LSN/ HSN with mid range needle relate to each other?

Many thanks in advance for your reply
 
Axial is right, not all engines tune the same but the Axial does need to be tuned in this manner.
My understanding is that the mid range needle determines where the LSN stops and HSN kicks in. Does anyone know what the proper workflow is? EXACTLY right.
Just remember what ever you do to the mid speed needle, you have to make the opposite adjustment to the LSN to kepp the LSN set properly.
 
Just remember what ever you do to the mid speed needle, you have to make the opposite adjustment to the LSN to kepp the LSN set properly.

hmm, so leaning the mid range will also lean the low end and i'm assuming richen the high end?
 
It juat changes where the HSN takes over at. The LSN actually seats into the MSN. That is why you have to adjust those two needles together.
Adjust you HSN to the type of driving you are doing...lots of top end speed runs it needs to be slightly richer than if you were just blipping the gas for short bursts.
 
ok now i'm really confused ... :\

On one hand axial says:
quote from http://www.axialracing.com/ftp/engines/techtips.html:
" The setting that come stock on your engine are for break-in purposes (first couple of tanks). To begin tuning for performance, the low-end and main needle will need adjustment. It's best to tune the low-end needle and idle first, then tune your main needle. Adjustments are done in tiny increments - looking at the clock, it's the range of adjustment from 12-to-1 (1 hour = 1/12th of a turn). To fine tune and make sure you get smoke on low-end (give it some throttle from a dead stop) and than thinning out as it reaches the top-end. Remember you should always see some smoke through out the full range. "


On the other they say this:
quote from AX001-I001.pdf
"We recommend that you do not touch the low speed needle. If
adjustment is needed, the low speed needle is set after the high
speed needle is adjusted. If the low speed needle is set too lean you
will experience the following:
1. Flame out at part throttle
2. Overheating
If you experience any of the above, reset to factory settings and start
the tuning process over.
"


So first they say to tune the low speed and idle first and then the high speed, and in the second example they advice not to even touch the low speed but if you really have to then do the high speed first.

which is it and why? (I emailed axial but I did not (yet) get a reply)
 
Some engine manufacturers will tell you to adjust the LSN first jsut so that it'll run long enough to tune properly, and almost ALL builders will tell you to leave the midrange needle alone.
I have several Axial mills and I always start with the LSN till I have enough time to get them off the bench and onto the ground, with a quick rev on the way. Then I work on the HSN, and touch up the LSN later.
Congrats on the Mantis. For a cheap truggy they handle very well and are extremely tuneable. You will need to watch how you treat the diffs though.
It is their only problem....
Also good luck waiting for a reply. I have emailed them a total of six times over four months and am yet to receive ANY replies......
 
I have found on most nitros, you really dont have to fool with the LSN near as much as you do the HSN. Pretty much, once i have broken in my mill's, i set the LSN, then do all of my tuning from then on with the HSN, with an occasional 1/16 turn on the LSN in severe weather changes.
 
Thanks to all for your replies, I still dont really understand the exact science behind engine tuning though but i'm not giving up and i'm learning everyday. Can anyone recommend good reading on how carbs do their job, especially with regard to the needles ofcourse ...

I found this, he speaks about running a nitro boat but I suppose a carb is a carb. Correct me if i'm wrong though ...

In any case it's good reading material I think ...
 
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