acexxxoasis

My Feedback: (4)

Hey guys finally got to the point where I can start and run my new ft rc8t Im so pumped! Anyway I had the engine in my savage which is an axial .28 spec 1s bumpstart I'm running the smallest restrictor I believe it to be 7mm which reduces airflow correct? So I would need to lean the engine out to compensate for less air correct? Is there a good starting point I reset the needles to factory specs and it will kinda idle but when I try and gas it it flames out but it will idle for a minute so low speed and idle are set? Or am I off track?

Argess

Everything you say sounds right, but you can never tell ahead of time what an engine will do on a particular day. You have to evaluate the engine performance and adjust accordingly. Of course when in doubt, richen it up, even though adding a restrictor should require a bit of leaning as it acts sort of like a choke otherwise.

How does it flame out when you nail the throttle?

If it starts off with good acceleration and suddenly quits, it is too lean. Richen the HSN about 1/4 turn and try again.

If it fights to get moving, never increases much in RPM,, and then dies, or immediately dies when you nail it, it is too rich. Lean the HSN about 1/8 turn and try again.

Once you get it close, you can your adjustments a little less drastic at a time until you like the way it runs.

Most of us don't like temp guns, but they can be useful when you arn't sure where you are....i.e. is it rich, or lean? If the temps are close to 200, it's rich, if close to 300 it's lean.

I usually get my engines to run at peak power, then richen the HSN close to 1/4 turn for safety's sake.

claudacio

My Feedback: (9)

Not to start anything here, but if using a smaller carb venturi would act as a choke it would be reducing the air intake (which you are correct about but...... a choke forces more fuel into the carb and less air) and when you do that without changing the needle settings, you would be reducing the amount of air into the carb making the air/fuel mixture richer (this is of course as you said the day/outside temps/weather conditions were exactly the same).

What you should do acexxxoasis is........... any time you fire up an engine for the first time of the day or when its had a few hours or whatever to completely cool off (this is dependent on what the weather does, if it gets colder or hotter then you will may have to retune but not do everything below), whether you are adding a smaller/larger venturi, or not changing anything at all, you should richen up the HSN a good 1/4 turn or more, richen up the LSN (you shouldnt have to change this all that much until you get the HSN tuned after you get it warmed up but richening it a little before you fire it up wont hurt) a good 1/8th of a turn and start the engine up and get it somewhat warmed up before you start driving it. Once the engine is warmed up completely and all the heat transferring from the engine to the chassis and everything else the engines heat is gonna transfer into is done (about a 1/2 a tank of running or so) start tuning it and take it from there.


A smaller venturi allows less air into the carb causing the engine to require less fuel, a larger one does the exact opposite. Just FYI, when you set the idle gap (start out with the idle gap set to the thickness of a penny or credit card (1-2mm) ), set it without a venturi in the carb, dont use the edge of the venturi like you would the edge of the carb. Set the idle gap without a venturi in the carb, slap the ventrui and air filter on and tune the HSN & LSN like you normally would and then figure out what the engine needs as far as the idle, it should be very minimal if you have the LSN set right.

I just added that last FYI part because I made that mistake for a long time and made tuning my engines harder than it should have had been.

skrilla

I truely mean no offense in my comments. It is an Axial Spec 1S. You are best off to remove the restrictor. That motor needs all the help it can get, so run it at it's full potential, it's probably underpowered or close tofor an RC8T