Help with RC8 B3.1 Throttle / Brake linkage

[pbrazendale]

Hi all,

Picked up an RC8 B3.1 followed the instructions it was a nice build, been running the engine in today a couple of tanks of idle and a couple of very slow driving.

My issue is that the car idles nicely and I have full throttle control I.e the carb opens all the way at full throttle, the issue is when I brake, upon braking the engine cuts as the carb fully closes past idle.

I’ve been racking my brains for a few hours and can’t figure it out, I am new to this so any suggestions / pointers would be very welcome.

I have attached some photos and a video to show the issue.

Thanks in advance.

https://i.imgur.com/IYV7fxF.mp4
https://i.imgur.com/EwSvwrc.jpg

[andy110m]

So we have a few issues here. Firstly, undo the finger pull grub screw to allow the throttle to close all the way. You can increase the idle speed by turning inwards the idle screw which is at the back of the carb above the exhaust spring. That looks like it’s turned out way to much. Turn that screw in for a higher tickover and wind it out to reduce it. That screw and the low end needle work together because Leaning the bottom will increase idle. In effect your engine was ticking over because you’d held the throttle open, not because it was set up correctly.

You also need to install a carb restrictor. You’ll notice the carb body is straight. You need to add one of the inserts to increase the air speed into the engine. I’d suggest a 6.5mm. They say the size on them but anything will be better than nothing. You’ll need to adjust the end stop point so the carb isn’t pulled open past that. The engine will run better crisper and have better run time.

Lastly I’d put an elastic band around the main needle and the ball pull to make sure the throttle is always fully closed.

Hope that helps.