Help needed! brake stalling!

[simple_83]

just upgraded my engine in my road car from a 15 to an 18. the problem i am having is that when accelerating and then stayin at constant speed the engine dies after a couple of seconds. and also when i put the brakes on the engine also dies. i have played around with the fuel mixture to make it leaner/richer and idle speed but can't seem to pin point the probelm.

any help would be greatly appreciated.

CHEERS

 

[HeartBreak]

It's your idle stop screw, located just below the air intake on the carb. Screw that in just enough to keep it running with the brakes applied. That should cure the problem.

 

[simple_83]

also i have adjusted the idle speed so there only a small openin but no matter what the bloody cars stalls when the wheels hit the ground.

 

[tmaxx pro]

try taking the brakes apart maybe you got something in them...

 

[Plaidfish]

maybe it's your flux capacitor while we're taking wild stabs at it....

set your screws back to stock settings.....turn your idle screw in so you have about a 1.5mm opening when brakes are applied......retune from there.....don't "mess" w/ the screws if you aren't sure which one to turn.....research engine tuning a lil if you're unsure and go from there......get a temp gun if you don't have one already and try to keep it in the 210-260 range...don't tune to a specific temp......that should start you off.....

 

[SVORay]

maybe it's your flux capacitor while we're taking wild stabs at it....

set your screws back to stock settings.....turn your idle screw in so you have about a 1.5mm opening when brakes are applied......retune from there.....don't "mess" w/ the screws if you aren't sure which one to turn.....research engine tuning a lil if you're unsure and go from there......get a temp gun if you don't have one already and try to keep it in the 210-260 range...don't tune to a specific temp......that should start you off.....

Well although the Flux capacitor is a really good guess, I'm going to go with the latter of the two. This sounds a little like what I went through a while back with my friends Tmaxx. It turned out we was running very lean and it cleared up once we went back to stock settings.


Ray

 

[kx250ryder]

OK, sounds like you have an inappropriately adjusted throttle linkage. To check it, remove the air filter and make sure that there is no change in the idle opening between when you let off the gas, and when you hit the brakes.

A common mistake that people make is to adjust their linkage such that the idle opening is set to 1mm or so, not realizing that the idle stop screw is not screwed in enough to keep the carb from closing any further when the brakes are applied. This can happen when you change gearing, because the motor is shifted from the position you originally adjusted the linkage for, as well as when you use a different engine.

To fix it, you need to mess around with the tension on the spring on the throttle linkage as well as the linkage's overall length. You will know when you have it adjusted properly, by seeing two things:
1.) There is no difference in the carb slide position between idle, and brake.
2.) The slide still allows the carb to open fully when full throttle is applied.

 

[HeartBreak]

Sounds more like the clutch is binding up. With the engine not-running, try to rotate the little gear on the front of the engine. It should rotate freely. If not, you have a broken part inside of that gear, and it will require disassembly to repair it.

 

[Monkey Wrench]

All of these tips are dead on accurate, but one thing that sometimes gets missed is centering your throttle/brake servo.

I would follow and check all of the tips presented so far, especially setting your high and low speed needles to stock and setting your idle set screw to hold the carb open at 1-1.5 mm. Make sure your clutch isn't binding and that the throttle/brake linkages aren't bent or anything.

Once you're to this point, take the servo horn off the servo, turn your RX and TX on, make sure you throttle trim is set to "0" and that your not pulling or pushing the trigger. Your servo is now centered, put the horn back on and you should be good to go (that is assuming everything else is OK).

Good luck!