Originally Posted by hotrob1
I bought a rs4 rtr3 with the nitro star 15fe engine when i start the engine the wheels spin high with fuel spitting out of carb i understand that the nitro star 15fe engine just has the high speed needle and the idle screw.
If you are sure there is no LSN low speed needle on the carbs throttle then you need to manage the LSN mixture using the HSN + IDLE GAP
It means you will need to close the HSN needle clockwise and lower the idle.
This is going to be quite difficult as it may also need a glow plug change to manage ignition.
Here's what I would try:
1) Remove glow plug and fuel lines and clear the engine of fuel by pullstart or starter box, replace fuel line and glow plug, do not prime.
2) Warm the engine up to 90c using a hair dryer or heat gun
3) Start the engine, it should idle high
4) Begin to lean (clockwise) HSN until idle gets higher and reduce idle
5) Rev engine for very brief period to full throttle and if HSN is too rich it will flood and die (Goto 1) If if starves of fuel raise the idle and richen (CCW) HSN
As I mentioned, if your glow plug is too cold for the ambient temperature and O2 levels, this may prevent you getting the engine tuned for a stable idle. I will require the HSN to be too lean and you could over heat and harm the engine.
A hotter plug will achieve an easier IDLE and I think this is most critical in a single needle engine. With what you have told us if there engine is idling high with a LOT of fuel spitting from pipe then it's likely you can get a decent idle while tuning a usable HSN. The hotter plug will allow for better combustion on a rich mixture, colder plugs need a leaner mixture as the richer mixture will stall at low revs.