can someone have a look at these please? (pics/vid)

[fish6634]

Hi all can someone have a look at the following please?

 

First off is this the idle control screw?

 

When i loosen it the inside can move in and out as oppose to the rotational movement what happens when the throttle is used off the transmitter.

 

Also if someone can look at the following and see if it looks ok?

 

The video shows idle/full throttle/idle/brake

 

http://i12.photobucket.com/albums/a242/fish6634/th_WP_20150201_004.mp4

 

The video is quite laggy so ignore the sound of the servo to the movement

 

 

thanks for looking sorry to be a pain

 

 

Graeme

 

 

[smeghead28]

That can happen with rotary carbs.

The problem is if you apply full brake you can also close the carb enough to allow the car to stall.

The linkages either need to be played with to lessen the effect or if you can adjust end points on your transmitter so even on full brake the carb isn't being pulled closed as well.

I had a HPI Super Nitro Rally many years ago that used to do the same.

Edited February 1, 2015 by smeghead28

[fish6634]

hi mate thanks for your reply, if that screw is the idle screw it doesnt seem to have any effect on my idle, does it need to be running so i can see the difference in adjustment?

 

i dont want the idle too high and wearing out my clutch

 

thanks for your reply

[R46]

Throttle linkage not set correctly, have radio & car on have the ch2 sub trim halfway loosen the end grub screw (no spring side) so can push linkage in so closes carb (if fully closes then now can static set idle @ .5mm then loosen grub screw by spring an reset tension on spring to keep carb close, now bring the end grub screw to servo an tighten.

Edited February 1, 2015 by R46

[Tamiyacowboy]

OK 

 

lets start with how the carb works, this then lets you see how the idler screw works.

 

the nitro engine carb is like a butterfly valve, when fully closed either air or fuel can make its way into the engine.

on the carb we tend to find a little screw with a spring on it , if we removed this screw we would find the hole leads direct to the fin/edge of the carbs valve.

(ever had a dripping tap where the valve is sticked open a fraction ?) 

 

so that idler screw is a bit like a sticky tap, it allows us to make a little gap in the valve so a very tiny amount of fuel and air can get in.

this very small amount means the engine ticks over ie idles over. 

 

Now the minimum gap be around half a mill wide, a little tiny gap.

if your servo rods are set incorrect, ie a little to long or short, when you brake to slow down

the servo rod pushes against the carb and it closes that very fine gap we should have and the engine stops.

 

turn on handset, and battery power to car, on the left stick you have an adjuster called trim. so put this in the middle

now lean over, and look down into the carb, see that valve inside ? now move your left stick back so if to brake

when your in full brake you should STILL see a little tiny gap, and a small spring on the servo arm will compress.

let the stick/throttle go to middle and you should still see a small gap. 

 

now if you find, the gap closes with full brake you can adjust the little capture clamp holding the springs on the servo rods.

adjusting these will let the pressure come off the carb and it will reseat back to idle gap.

 

nitro carbs are like the old cars, they need hands on work to set them up for that sweet spot the driver wants.

think of it as your tuning a dual webber carb on a big old V8 motor. you wnat it to burble away but not stall out so you adjust the idler

screws on the carbs to set them for idle at no throttle, we nitro guys we just set it for idle at no throttle and full brake ( our brake is tied in with our throttle unlike a real car ).

 

 

Idle screwed out wards means the gap in the carb is less it adjust the carb and closes the gap , to much and the car will not start or cut out when braking.

 

idle screw screwed inwards. means we open up the gap and the engines idle speed rpm start to rise, more inwards that screw goes the more air and fuel you let in past the valve.

To much and the engine will act eratic and drive away without any brake or throttle being used. 

 

now being an awesome dude and wanting to help you out and all the other guys new to Nitro

here is the most perfect video that explains how your throttle/brake linkage works and how one can set it up to work correctly.

notice right at the start he opens, closes and brakes, the carb opens closes and stays closed with a gap this is what should happen to your carb when working correct.

 

Edited February 1, 2015 by Tamiyacowboy

[fish6634]

thanks for that big write up buddy i am going to have a play with the car now

[Tamiyacowboy]

Your welcome fish 

 

we have all had the same problem manifest itself , and nodoubt used the same methods,

and same head scratching  why is it not working right questions. 

 

the more you work with and on your model the more you will learn about how  part works.

 

I do hope the video and the info given helps you understand how the brake and throttle link system works

and gives you an insight in how we set them up correct. 

 

If you do still struggle we have a large band of bashers, that are running nitro and maybe a member close enough

to turn up and help you work out and fine tune you idle and engine tuning. so never be afraid to ask for help