XTM Racing X-Factor2, Operation Manual

Page: 15 / 28

15
After your engine has been broken in, you can set the high and low speed needle valves for optimum engine performance.
✦ ✦ ✦ ✦ ✦
IMPORTANT
✦ ✦ ✦ ✦ ✦
Be careful to never lean out the engine too much. Remember that the lubricants for your engine are suspended in the
fuel. If you lean out the fuel mixture too much you will also be lowering the amount of lubricant entering your engine. Less lubricant
means more chance of your engine overheating and possible engine failure.
Step 2: Fine Tuning the Engine
Setting the High Speed Needle Valve:
❑
Start the engine and remove the glow starter from the glow plug, then allow the engine to warm up for about 10 seconds.
❑
After the engine has warmed up, drive the truck as you normally would. If the engine seems to be running rich, lean the high speed
needle valve about 1/16 of a turn at a time until the desired setting is achieved. Always make sure you run the engine slightly rich - you
want to be able to see a white exhaust trail at all times.
Setting the Low Speed Needle Valve:
❑
Start the engine and lean out the high
speed needle valve as per the previous
procedures. Close the throttle until the
engine slows down enough so that the clutch
is disengaged and the wheels don’t turn when
the truck is lifted from the ground. Allow the
engine to idle for about 10-15 seconds.
❑
While holding the truck off the ground
(making sure to keep your fingers out of the moving parts) quickly open the throttle in a short burst. If the engine just stops running as
soon as the throttle is advanced, the low speed needle valve is too lean. With the engine stopped, richen the low speed needle valve
about 1/16 of a turn.
❑
Restart the engine and repeat the procedure above until the engine will transition smoothly and quickly. Very slight hesitation in the
transition is normal.
❑
If you quickly advance the throttle and the engine seems to be very rich during transition (i.e., lots of white smoke coming from the
exhaust pipe and very rough sounding), the low speed needle valve is too rich. With the engine stopped, lean the low speed needle
valve about 1/16 of a turn.
❑
Restart the engine and repeat the procedure above until the engine will transition smoothly and quickly. Very slight hesitation in the
transition is normal.
❑
Now drive the truck as you normally would for a while to get a feel for how the engine reacts to throttle. Now that you know the proper
way to tune the engine, you can make slight adjustments to the carburetor until you are satisfied with the performance.
24.7 ENGINE UPGRADE TIP
To get more power from your engine you can use fuels
containing up to 30% nitromethane. We must caution
you, though, that once you run the engine with increased
nitro you may not get satisfactory results if you decide to
go back to a lower nitro content. Also, if you use fuels
containing 30% nitro, we highly suggest adding a .10mm
head gasket (# 148418) to lower the compression ratio.
If you don’t lower the compression ratio, overheating and
erratic running will likely occur.
Step 3: Basic Engine Maintenance
To keep your engine operating at peak performance there are some basic maintenance procedures that need to be performed on the
engine on a regular basis:
●
After you are finished running the engine for the day, pinch the fuel line to stop
the engine. This will allow the engine to burn any excess fuel out of the crankcase.
●
Remove the air filter element and wash it thoroughly in warm water and a small
amount of liquid detergent. After it's clean, allow it to dry, then reoil it and install it
back into the air filter housing.
●
Remove the glow plug from the engine and squirt several drops of high-quality
after-run oil into the glow plug hole. Pull the pull-start cord several times to distribute
the oil throughout the engine, then reinstall the glow plug. The after-run oil will
prevent the inside of the engine (especially the crankshaft bearings) from rusting.
●
Clean the outside of the engine using a heavy brush and nitro car cleaner, then
dry the engine, using a rag or compressed air.
KEEP IT SMOOTH
Loop four nylon
ZIP ties around
the corners of
the engine's
cylinder head,
making sure that
t h e r a t c h e t
p o r tion of the
t i e s a r e u p
t o ward you. When your truck flips over, the ties will
prevent the cylinder head from being scratched and gouged.