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Old 12-18-2011, 04:32 AM   #16
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Hang in there, nitro can be a bit frustrating sometimes. Ok, let's go back to the start.

Get a fully charged receiver and radio pack.
Radio on, receiver on (engine not running).
Remove air filter and look down at the carb opening.
At neutral the carb should be fully closed (except for a very slight opening for idle)**.
Squeeze trigger fully. The carb opening should open fully (should look like a perfect circle).
Release trigger to neutral. Position should return to **.
Fully brake and release. Position should return to **.
Do this a few times back and forth while looking down the carb hole in any sequence and as fast or slow as you want. This action should happen every time exactly as above.

If it isn't you need to realign your throttle linkage properly using the stoppers and spring so that the action is consistent. If it still isn't working maybe your servo arm is stripped. Check that too.
Fyi, At neutral the carb should never stay open on its own.

If all that is correct, then your radio settings are good.
Now close both LSN and HSN all the way in. Be careful you don't over tighten them.
Then turn them both out 2.5 turns.
Start engine.
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Old 12-24-2011, 02:30 AM   #17
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Quote:
Originally Posted by modelfan View Post
Hang in there, nitro can be a bit frustrating sometimes. Ok, let's go back to the start.

Get a fully charged receiver and radio pack.
Radio on, receiver on (engine not running).
Remove air filter and look down at the carb opening.
At neutral the carb should be fully closed (except for a very slight opening for idle)**.
Squeeze trigger fully. The carb opening should open fully (should look like a perfect circle).
Release trigger to neutral. Position should return to **.
Fully brake and release. Position should return to **.
Do this a few times back and forth while looking down the carb hole in any sequence and as fast or slow as you want. This action should happen every time exactly as above.

If it isn't you need to realign your throttle linkage properly using the stoppers and spring so that the action is consistent. If it still isn't working maybe your servo arm is stripped. Check that too.
Fyi, At neutral the carb should never stay open on its own.

If all that is correct, then your radio settings are good.
Now close both LSN and HSN all the way in. Be careful you don't over tighten them.
Then turn them both out 2.5 turns.
Start engine.
I tried to check everything u listed above and true is that the carburetor was opening too much during idle but the issue i observe was when i press brake the carb would close totally and the engine would stall and also i wasnt able to obtain even a 1.5mm gap so i took it out and analysis and realize that the idle screw would onli work to the max of 2mm ++ and i cant close it anymore further..should i replace the carburetor instead or ? And if i want to replace the carburetor,can i change any 6.5mm .18 engine carburetor to it?
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Old 12-24-2011, 10:21 AM   #18
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Originally Posted by m33g0 View Post
I tried to check everything u listed above and true is that the carburetor was opening too much during idle but the issue i observe was when i press brake the carb would close totally and the engine would stall and also i wasnt able to obtain even a 1.5mm gap so i took it out and analysis and realize that the idle screw would onli work to the max of 2mm ++ and i cant close it anymore further..should i replace the carburetor instead or ? And if i want to replace the carburetor,can i change any 6.5mm .18 engine carburetor to it?
Okay, I'm not sure what you are trying to say but it sounds like the following:

At neutral, your idle was too far open causing the engine to "race" at idle.

Second, when you hit your brakes the throttle closed completely.

To fix these, start with problem 2. This is controled by the idle stop screw. The further "in" you turn it (this is screwing it in clockwise) the MORE open the idle will be. Sounds like you tighted it all the way down and yes, this is going to make the opening too large. Back off that screw until you get your desired opening.

At that point, you should now adjust your neutral position so that, at neutral, the carb is at the same position as it is at full brake. I usually adjust my neutral so that it takes a bit of trigger movement to get the carb to react. This way you know you won't have the carb "hanging open" a bit if you just go from throttle to neutral.

Once you have these set, start the engine and let it get up to temp then apply full brakes. Right now, the idles shouldn't drop if everything is adjusted as above. If the idle is still too high, turn the idle stop screw out (CCW) slightly to lower it. If the idle is too low, turn the idle stop screw in (CW) and the idle will come up. Once you have the idle where you want it, release the brake. If the idle "jumps up" when you release the brake, you need to adjust your throttle trim again to set neutral properly.

IMPORTANT NOTE: When the car is at idle, it should be able to freely roll back and forth. MANY times what novice nitro guys will do is set a high idle and to get it to stop moving they will set the car up so the brakes are applied at neutral to keep it from moving. DO NOT DO THIS. Check that the car will roll freely in neutral. Failure to do so will result in a melted glob of plastic where your clutch use to be.

Hope this helps.

Last edited by Robotech; 12-24-2011 at 10:33 AM.
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Old 12-24-2011, 01:11 PM   #19
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Firstly thank for helping me out as I am really noob about this,I was trying to say I had already ccw the idle screw but the carb couldn't close till 1mm gap the max I can do was 2mm and and it dosent close up the gap further even until the idle screw was nearly dropped out from the hole.is my carb spoil ?
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Old 12-24-2011, 02:50 PM   #20
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pull off the air filter and turn on the radio and the car DONT START IT YET. if when you push the trigger for brakes and the carb closes, you need to set the throttle linkage or use the trim but setting the likeage would be better. you want the carb closed with only enough idle gap at idle. hope this helps have fun.

or setting the throttle servo to neutral might the answer.
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Old 12-24-2011, 10:58 PM   #21
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turn both mixture screws in all the way, screw both out 3.5 turns.
Adjust idle screw to suit
Replace with a new glow plug os 8
while the glow plug is out, turn upside down and pull the pull start a few times.

The amount of cars that come through each week at work and I quickly do those few steps she starts up.

After its run in adjust your mixture setting too.
Any problems just message me
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Old 12-25-2011, 09:40 AM   #22
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Sounds like you have a problem with your throttle linkage
and not the carb.
First off, does your radio should have some trim adjustments on
it. Make sure that the trim adjustment for the throttle/ brakes
is set to zero. If it is a knob type adjuster, turn it so the detent
is in the middle (+ I -).
Take the air filter off the carb, turn the radio on, turn the receiver
switch on. Is the carb slide going closed against the idle adjustment
screw now ? If not, you need to adjust the linkage going to the
carb. If it is way off, you may have to move the arm that connects
the linkage to the servo. If you do have to move the arm, make
sure you check to make sure that the splines on the servo and
inside of the arm aren't torn up.
If this takes care of your problem, make sure to cycle the servo
a few times each way (full throttle to full brake) to see if your
adjustments remain the same. If it looks like it has changed
vastly again, you may have a bad servo or arm. Don't attempt
to run the car until you correct the problem. Having your car
run away at full throttle always ends up costing you alot of
money.
I hope I may have helped you out, good luck.
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Old 12-26-2011, 10:13 AM   #23
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Dear friends,if I want to replace a carb but nt the hpi original carb what are the things I need to look upon to such as size of 6.5mm ? and next question is if I wanna change to another engine , hw would I know if my chassis can fix it in such as I am using the t3 .18 engine now ,how would I knw if I can fix other engine in. Thanks !
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Old 12-26-2011, 11:04 AM   #24
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Quote:
Originally Posted by m33g0 View Post
Dear friends,if I want to replace a carb but nt the hpi original carb what are the things I need to look upon to such as size of 6.5mm ? and next question is if I wanna change to another engine , hw would I know if my chassis can fix it in such as I am using the t3 .18 engine now ,how would I knw if I can fix other engine in. Thanks !
Okay, why do you want to replace the carb?

I don't want to sound like a jerk, but the reality is that you are still learning how all this works and chances are the problem isn't the carb, it's you. Now, that's kind of harsh but that's something you need to realize. You're getting some good help here and if you sent the motor into HPI and they worked on it, I can promise you that it came back to you in a working condition.

Go through the steps I gave you before. Go through them exactly as I laid them out even if you think you've covered them. Go through them with a positive attitude and you will find your problem.
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