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classic motorcycles like the
RD350 YPVS, restomodding
ensures that the bike continues to
deliver the same thrills it did in its
prime, but with the added benefit
of modern-day reliability, better
handling, and improved comfort.
The Mechanics of the
Yamaha RD350 YPVS
To understand the importance of
restomodding the RD350 YPVS,
it's crucial to examine the key
components that made this
motorcycle so special in its original
form. From the engine to the
suspension, the RD350 YPVS
was designed to offer a unique and
engaging riding experience.
The YPVS: Yamaha Power
Valve System
The most significant feature of the
RD350 YPVS was its engine,
which incorporated Yamaha's
innovative Power Valve System
(YPVS). The YPVS used a set of
mechanical valves inside the
exhaust port that could open and
close based on engine speed.
This allowed for more precise
control over exhaust timing,
improving the power delivery at
different rpm ranges.
· Low-End Torque: The
YPVS system allowed the
RD350 YPVS to have
better low-end torque
compared to other two-
stroke motorcycles of the
time. Traditional two-
strokes often suffered from
a lack of usable power at
lower revs, but the YPVS
system helped bridge this
gap by optimizing the
exhaust timing for better
throttle response in the
mid-range.
· Top-End Power: As the
engine revs climbed, the
YPVS system opened the
exhaust ports further,
allowing the engine to
breathe more freely at high
rpm. This translated into
more top-end power, giving
the RD350 YPVS a thrilling
top speed and impressive
LHR Motorcycle Magazine Issue 09
acceleration. 1. Engine Upgrades: More
· R e l i a b i l i t y a n d
Smoothness: The variable
exhaust timing also helped
reduce engine knocking
a n d p r e - i g n i t i o n ,
contributing to smoother
p o w e r d e l i v e r y a n d
improved engine longevity.
Lightweight Chassis and
Handling
In addition to the engine, the
R D 3 5 0 Y P V S f e a t u r e d
l i g h t w e i g h t c h a s s i s
contributed to its agile and
responsive handling. The bike's
frame was made of steel, offering
a balance of strength and
lightness, while the front and rear
suspension systems were
designed to provide a smooth and
controlled ride. The motorcycle's
relatively low weight (around 160
kg or 350 pounds) made it highly
maneuverable, and its sharp
steering geometry ensured that it
could tackle tight corners with
ease.
Braking and Tires
The RD350 YPVS was equipped
with disc brakes, both front and
rear, providing sufficient stopping
power for the bike's weight and
performance. However, compared
to modern standards, the brakes
could be considered somewhat
basic, especially when compared
to the advancements in brake
technology available today.
Similarly, the tires on the RD350
YPVS, while suitable for the time,
weren't as grippy or durable as the
performance tires available now.
Key Components of
a Yamaha RD350
YPVS Restomod
Restomodding a Yamaha RD350
YPVS involves taking the bike's
stock components and enhancing
them for a more modern riding
experience. The goal is to retain
the essence of the original while
introducing upgrades that improve
performance, safety, and comfort.
Below are some of the key areas
where restomods typically focus:
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Power and Reliability
While the stock RD350 YPVS
e n g i n e w a s a l r e a d y a
masterpiece, many restomodders
c h o o s e t o u p g r a d e k e y
components to improve the bike's
power output and reliability.
· Cylinder Porting: One of
the most common engine
mods is cylinder porting.
This involves modifying the
a exhaust and intake ports to
improve airflow, which can
t h a t increase horsepower and
improve throttle response.
· Piston and Cylinder Kit:
Upgrading the pistons and
c y l i n d e r s t o h i g h -
performance aftermarket
k i t s c a n a d d m o r e
displacement and increase
overall engine output.
· I g n i t i o n S y s t e m :
Replacing the stock ignition
system with a modern
digital CDI (Capacitor
Discharge Ignition) system
can improve spark timing
and efficiency, resulting in
better throttle response,
increased reliability, and
smoother running.
2. Suspension: Improved
Handling
The suspension on the RD350
YPVS, while functional, can be
enhanced for better performance
and comfort. Modern shock
absorbers with adjustable
damping, preload, and rebound
settings can provide a much
smoother ride and more control
over rough terrain.
· Front Forks: Replacing
the original front forks with
modern inverted or fully
adjustable units can
improve the bike's front-
end handling, making it
m o r e s t a b l e a n d
responsive, particularly
when cornering.
· Rear Shocks: Upgrading
the rear shocks to units with
a d j u s t a b l e p r e l o a d ,
damping, and compression
January 2025