After Break-in Tune

[Javage]

So I got the break-in done, had trouble getting it started so a guy at the hobby store played around with the idle/low/high adjustments to get it thru the break-in.

I was thinking it was running too lean on bottom end and too rich on top end. . . when I would pull full throttle under acceleration it would stumble/studder and not really reach full topend(or what I would assume would be topend power).


So after some reading I decided to put all the adjustments back to "stock/flush" and retune from there.

At first I had trouble getting it to start, then once I got it cranked it would idle and die after a few seconds. .. played around with the idle adj. screw and got it to idle fairly well(or at least I think);
-Now when I cruise around at low-mid throttle and let off, it acts like its sticking and still leaving the carb opened up? I have to tap the break to kick it into "neutral".
-Also I still haven't got it to reach full top-end potential. . .?
-Then I pulled the air filter tube off and noticed the carb is fully opening up, and I can't seem to set it so that it will.


On the throttle servo arm, it should be set at a 90' angle, and the throttle adjustment knob on the trans should be in neutral, correct? If the idle is not correct should I be using the knob on the remote or the idle screw to make it idle properly?


This is probably covered somewhere in here but I've been searching thru SOO much info on here it gets hard to find. So if you can any help for this noob is appreciated.

 

[MikeK1981]

You need to set your idle screw so the carb opening is 1mm when fully closed, no less. Then you need to set your throttle trim on the radio to neutral and then take your throttle linkage off the carb and adjust it so that when the trigger is at neutral the carb is closed as far as it will go (1mm). You'll see that the throttle linkage is threaded to adjust it's length. What's happening is that you are hitting the brakes and the carb opening is changing when you do, you don't want that. The purpose of the idle screw is to set the MINIMUM opening so when you hit the brakes it does not close all the way and stop the motor. If you cant get it to start at that setting you probably need to lean it out some, too much fuel will flood it and it will lock up.

 

[MikeK1981]

Also don't change your low end yet, it is probably not rev-ing high enough because your High Speed Needle is way too rich. Lean it out 1/12 turn at a time until you get better performance and keep an eye on your temps while you do to make sure your not getting too hot. Once you get the motor performing well and maintain a good temp then you can adjust the low speed needle to get better throttle response and easier starting. I'm fairly new to MT's myself and I'm sure the guys here can help you out more, but this seems to a source of confusion for many so don't get discouraged and good luck!

 

[AllanQ]

-Then I pulled the air filter tube off and noticed the carb is fully opening up, and I can't seem to set it so that it will.

Not sure what you mean here, I am assuming you mean the carb is not fully opening. If this is the case, it sounds like your linkage is binding up, or you may need to adjust the servo horn on the servo itself.

Before I assume any more, do you have the stock TX and servos?

Watch this vid to help out in tuning your motor.

https://www.hpisavageforum.com/forums/showthread.php?t=1955

set the idle knob on the tx to neutral and adjust the idle screw on the side of the engine. you can fine tune the idle if needed with the throttle trim knob.

 

[Javage]

I am assuming you mean the carb is not fully opening. If this is the case, it sounds like your linkage is binding up, or you may need to adjust the servo horn on the servo itself.

Before I assume any more, do you have the stock TX and servos?

Watch this vid to help out in tuning your motor.

https://www.hpisavageforum.com/forums/showthread.php?t=1955

set the idle knob on the tx to neutral and adjust the idle screw on the side of the engine. you can fine tune the idle if needed with the throttle trim knob.

Correct, sometimes the carb is fully opened, sometimes not.
Jow do I adjust the servo, and yes everything 100% stock.

I've watched lots of videos, most just tell how to tune. . .

I'm having trouble with the throttle "sticking". . . I have to hold the brakes to slow it down.

Also it hesitates on acceleration.

 

[Javage]

You need to set your idle screw so the carb opening is 1mm when fully closed, no less. Then you need to set your throttle trim on the radio to neutral and then take your throttle linkage off the carb and adjust it so that when the trigger is at neutral the carb is closed as far as it will go (1mm). You'll see that the throttle linkage is threaded to adjust it's length. What's happening is that you are hitting the brakes and the carb opening is changing when you do, you don't want that. The purpose of the idle screw is to set the MINIMUM opening so when you hit the brakes it does not close all the way and stop the motor. If you cant get it to start at that setting you probably need to lean it out some, too much fuel will flood it and it will lock up.

I set it so that the opening is approx. 1mm, radio at neutral.

The throttle linkage, the rod that connects the servo to the arm, or something else?

 

[Javage]

From watching the HPI Getting Started DVD, I assumed I was running lean; it shut down at full throttle w/ tires off the ground- if I got it up to FThrottle.

I found(or think) that I screwed the carb linkage rod out too much and it was causing the carb to open up more than it should.


Ok, took the throttle linkage off and adjusted all the rods to factory specs via the manual-> at full brake the carb closes just under 1mm-> when idle its approx. 1mm-> and at full throttle it opens fully.

Also got the idle screw set properly(hopefully).

It starts and idles fine now. . .

It still has a small amount of hesitation on accel. and sometimes the throttle will stick, but not as bad as before.


I played around with the HSN and flipped it over backwards and now I have some cosmetic damage along with a bad glow plug:nutshot:

If anyone cares to throw out any other info/tips it will be appreciated.