Originally Posted by Werks

Hello sjracing, first off thank you for picking up one of our engines! I'm sorry that your request for info is kinda getting lost in between all of this drama lol! In any case in regards to break in please take a look at my break in instructions, this is a really simply system to use and is especially good to use if you are newer to tuning these type of engines as it is virtually impossible to run the engine too lean, which is important during break in!

Now you mentioned that your experience was in running nitro planes, so you have experience tuning engines. As you mentioned planes are a little different as they only have a HS needle and of course they are cooled by the prop so temps are not so big a factor. In any case with your carbs we have 3 basic adjustments, that is the HS needle that you are familiar with which sticks up from the top of the carb on a brass post, we have the LS needle which is the one on the end of the slide right where your servo linkage connects and we have the idle stop screw which is the screw that sits at a 45 degree angle right behind the carb venturi (if you look at the engine from the top). These are the three screws that you will be adjusting to break in your engine.

The way that you have to look at these is that the HS affects the overall fuel delivery (across the entire range of throttle movement), the LS affects the initial fuel delivery (from roughly throttle closed to about half way open) and the idle stop screw only dictates the minimum amount of air that the engine will get or basically how far you can close the throttle. At half throttle and above you would basically tune the engine the same way that you would your airplane motor. But at half throttle and below look at the LS and the HS kinda like your garden hose and the tap. The HS needle is the tap at the wall, if you turn it wide open you can move a lot of water through the hose (or in our case fuel through the carb) but if your nosle on the end of the hose (LS needle) is barely open you will only have a little bit of water going through it. So when breaking in your engine you want to have a lot of air and fuel flowing through your engine (you want the engine to be rich). The way that you do this is set your idle stop screw pretty far open (so you have a lot of air coming into the engine) and then you have your needles open really far so that you have a lot of fuel coming through the engine also.

Following my instructions each tank you lean the needles slightly, this means that you then have less fuel coming into the engine so you naturally need to reduce the amount of air also which is why you reduce the air gap using the idle stop screw. Take a look at my instructions with the engine actually in your hand and I think that it will start to make a little sense. Keep in mind that while doing this your engine will be telling you what needs to happen by what it is doing so once you start the system it really makes sense. Give it a shot and while your doing it if you have any questions please do not hesitate to ask!

Regards,

Ron