Chapter 7 – Cylinder head and valves
Manual de Oficina AJP PR3/PR4 (2015) 7 - 13
Assemble the tensioner guide of the timing
chain in the cylinder head and secure it with
the respective pivot bolt with aluminum
sealing ring, tightening with the specific
torque.
Install the cylinder head (complete with
valves) on the cylinder, while maintaining tight
the timing chain not to jump outside of the
correct position on the crankshaft.
For engines 200 / 240cc, introduce the rubber
sealing ring on the left front cylinder pin, fitting
it into the countersink existing on the surface
of the cylinder head assembling it over the
metal flange washer.
Observations:
Only the motors 200 and
240cc require seal on the left front cylinder
bolt, to prevent water or mud pass through the
front opening existing in the cylinder head into
the stud hole in the cylinder and cylinder
head. There are three different types of
sealing ring applied to the sealing bolt in
engines of PR3 / PR4 bikes:
1) In older engines 200cc (PR4-2005 /
2007) with cylinder rods of Ø 6.5 mm,
the seal was made with a rubber
bushing with tab in the middle, wherein
one end fitted on the pin hole at the
cylinder and other on the cylinder
head.
2) In 200cc engines that equipped the
first PR3 (2007/2009), the seal was
only a rubber washer (rectangular seal
14,3x6,5x2,5mm) that was lodged in
countersink existing on the surface of
the cylinder head.
3) In the engines 200 and 240 cc most
recent (with reinforced cylinder bolts
with a diameter of 8.5mm) fitted the
PR3 / PR4-200 / 240 (2011-2013)
there was an improvement in the form
of sealing this stud cylinder and it is
currently used a new rubber sealing
ring with an inner lip and
complemented with a special mounting
plate washer with tab on the sealing
ring both being housed at the
countersink existing in the cylinder
head.
Except few units, almost all of PR3 / PR4-
240cc engines (2013) are equipped with the
same cylinder head of the 200cc engines with
combustion chamber recessed / flat and
valves with a diameter smaller than the 240cc.