HSP Behemoth Stalling!

[behemoth]

Hi there, i am a newbie to this forum

i have a HSP Behemoth (3.0 cc) truggy.

the engine starts fine and there is good compression. it accelerates and revs up fine and there is plenty (but not too much) blue smoke see at all rpms when the engine is running.

the problem i have is when i bring it to a stop, it stalls. if i dont immediatly blip the throttle after starting and keep the truggy moving, it stalls.

how can i fix this? should i adjust the iddle screw, low end screw on the carb or the needle adjustment screw?

i dont think i need to adjust the needle screw as i dont think its running too rich or too lean.

many thanks

 

[Rolex]

If you are getting a good take off and a good top end, don't change the needle settings. You will need to raise the idle adjustment screw with the trim on the radio all the way down and the brake applied.

Let us know how it works out for you, and welcome to RCNT. We're glad to have you with us.

 

[Monkey Wrench]

Hi there, i am a newbie to this forum

i have a HSP Behemoth (3.0 cc) truggy.

the engine starts fine and there is good compression. it accelerates and revs up fine and there is plenty (but not too much) blue smoke see at all rpms when the engine is running.

the problem i have is when i bring it to a stop, it stalls. if i dont immediatly blip the throttle after starting and keep the truggy moving, it stalls.

how can i fix this? should i adjust the iddle screw, low end screw on the carb or the needle adjustment screw?

i dont think i need to adjust the needle screw as i dont think its running too rich or too lean.

many thanks

Two things I suggest:

1. Make sure your throttle/brake servo is centered. Sometimes if the servo isn't centered, when you hit the brakes it'll close the carb and stall the engine.
2. Adjust the idle set screw (which I think is the culprit here) to allow a small gap in the carb when the brake is engaged or the throttle is at neutral.

If the engine is running fine, I'd refrain from adjusting the mixture needles.

 

[behemoth]

hi guys,

thanks for your help.

i have the engine idling fine now when starting from cold with 0 trim.

however the problem i now have is that when it has been driven for say half a tank and is up to temp when i let got of the throttle it seems to be pulling itself along still and when i pull the brake and it comes to a stop, it stalls.

what can be wrong, is it still the idle screw that needs adjusting or do i need to adjust the low end screw? i bought the truck second hand so I'm not sure if the low end screw is at factory setting, how do i check this?

many thanks

 

[Rolex]

As it warms up, and the fuel goes down, the pressure in the system tends to make it run lean.
Re tune it with the engine up to temp, and down to 1/2 a tank. You'll need to richen the LSN and readjust the idle setting.
Don't worry if you need a minute to get it warmed up from a cold start after the tune, that's normal.

 

[behemoth]

excuse my ignorance, is the LSN you talk about the needle valve or the low end screw?

many thanks

 

[Rolex]

The LSN is "Low speed needle".

 

[behemoth]

many thanks, just a small confusion.... you call it LSN i call it LES (low end screw)....

should i screw this flush, then make adjustments as is nescessary? should i be screwing it in or out when i am adjusting it?

cheers

 

[Rolex]

It's the LSN...Low Speed Needle, since it affects how the engine responds from a stop to about half throttle.
Flush with the ring is the factory default setting. As it breaks in, it needs to be leaned slightly. You do that by turning it in, like a water faucet. Turn in, less flow=leaner. Turn out, more flow=richer. Only adjust it by 1/16 turn at a time, and do it with the engine warmed up. Keep an eye on the temp.

 

[Monkey Wrench]

To help with keeping things straight, to make a setting leaner, turn clockwise. To make a setting richer, turn counter-clockwise. Same as what Rolex posted, but it helps me keep things straight by remembering the clock.