Cleaning The Baja Engine
HPI Tutorial - How to Clean Your Baja 5b Pull Start and Engine
The Baja 5b 1/5 scale buggy is an off road vehicle. When driving off road your buggy may get dirty, especially if used in damp conditions. It is important to keep the engine and pull start of the Baja 5b clean to keep it running reliably and to maintain top performance.
Pull Start Cleaning
The pull start unit on the Baja 5b may need regular maintenance
if the buggy is run in damp or dirty conditions. The pull start may
fail to operate after your Baja 5b has been run in damp conditions
and then left to dry. This is caused by contamination with grit or
dirt, but this is really easy to fix by cleaning. To clean the pull
start mechanism you first need to remove it from the engine. To do
this first you need to remove the left rear wheel from the buggy to
gain access to the screws that hold on the pull start mechanism.
With the left rear wheel removed you have access to the 4 screws
that hold on the pull start mechanism. Undo these 4 screws with the
supplied 3mm allen key. 
With the complete pull start mechanism removed you can see the
moving parts of the mechanism. To clean the mechanism you need to
take it apart. To do this you need to unscrew the screw that holds
it together. 
Remove the screw and the metal plate. Now you can remove the
sliding part of the mechanism so that you can clean the sliding
surfaces properly. It is grit and dirt on these sliding surfaces
that cause the pull start mechanism to stick. 
Remove the sliding part of the pull start mechanism by lifting
and twisting in a clockwise direction. Now you can clean the pull
start mechanism, pay special attention to the surfaces that slide
over each other. Dirt and girt on these surfaces causes the
mechanism to stick. 
Once you have cleaned the moving parts of the pull start re
assemble it and then pull the pull start handle a short way out.
The sliding part of the pull start should move out from the pull
start mechanism. When this part moves outwards it engages with the
flywheel of the engine, allowing the engine to be turned. 
Before re-attaching the pull start mechanism to the engine it is
a good idea to clean the flywheel, paying particular attention to
the fins on the flywheel. These fins draw cooling air through the
pull start housing, if they are full of dirt and grass they will
not be as effective and the engine cooling will be reduced.
Once you have cleaned the pull start and the flywheel you should reattach the pull start mechanism to the engine.
Engine Cleaning
As the engine is air-cooled it is important to keep the outside
of the engine clean. Airflow around the engine removes heat from
the engine and keeps the engine in the normal operating
temperatures. If the outside of the engine becomes covered in dried
on dirt the engine may overheat. To clean the engine you need to
brush off any mud, dust, grass etc from the outside of the engine.
Pay special attention to the air slots in the pull start housing as
this is where cooling air is sucked in. 
You also need to clean the engine cylinder head cooling fins.
The engine is cooled by air passing over these fins, if they are
covered in dirt the engine cooling will be less effective and the
engine may get hot. 
With the engine clean and free from dirt and debris it will run cooler and give you the best performance.