Yamaha
RD YPVS Tuning
RD50
| RD80
LC | RD125 LC
| RD200 Gallery
| RD250 Gallery
| RD250LC |
RD350 LC | RD350
YPVS | RD400
| RD Restoration
| RD500 LC
| RD500 Gallery
| LC Tuning
TZ 350 G Hitachi, Femsa & Motoplat ignitions
improve performance a lot but don't generate
electricity for your lights so are no good
for road bikes .After market pipes will also
give a good power boost. Some will just move
the power around not actually give more B.H.P
.Tel your tuner what pipes you are using so
he can match the tune to the pipes .Otherwise
you could get a top end screamer that doesn't
work below 10,000 rpm grate fun ok for the
track but useless for the road and hard on
the pistons and rings .
Yamaha saw fit to give the early YPVS a horribly
under sprung, poorly damped, non-rebuild able
rear shock. This can still be said of the
latest Brazilian model, though the FII are
a little better. Despite wider, air-assisted
fork tubes then the deposed LC's the YPVS
front end is still too soft for hard use.
Using tapered roller head bearings is a
must and improve the front end a lot ,as will
adding a steering damper even a cheep one
will do . I found doing both of these things
improved the front end of my FII a lot.
Experience gained from the pro-am {YPVS only}
and marl borough championships led to the
development of the Hegira spax shock at around
£250. It has adjustable pre load and
rebound damping with a choice of springs.
Fork conversion kits to improve damping and
spring rate rate including springs and oil
seals will cost around £160 .Maxton
do the Maxton Koni shock with damp and rebound
adjustment for the rear .
The carbs, pipes & ignition are the biggest
restrictive on any LC or YPVS. The best standard
carbs are the FI YPVS 26mm's. TZR or RD 400
E 28mm's are more then adequate for most road
tuned bikes. TZ 36mm power-jet carbs are my
choice for a fully tuned YPVS's.
 Skimming
the head raises the compression and does improve
performance even on a standard engine, making
it slightly peaker. the heads shown here have
been made like this for easy maintience on a tuned
motor.
Hear are two YPVS barrels, the one on the
left tuned the other standard, you can clearly
see the difference. At least I hope so when
I fit them to my latest project.
The YPVS has a bridged inlet port allowing
a more tuned inlet area then the LC without
the piston slapping. The big end rollers and
con rods are 1mm wider, giving the crank a
longer life.RD500 big end's are the same size
as the YPVS but have an extra roller in so
are a good choice for a tuned bike.
The 83 YPVS peaked at 9.500 rpm, but the
FI revised exhausts moved this up to 10.000rpm.
then Yamaha ruined it with the FII's restrictive
carbs, ignition & exhausts brining it
down to 8.500rpm. The FII is less prone to
seizures and the pipes do look loads better
then the earlier ones.
Most people would be shocked at the true
B.H.P of their bikes. You could get a good
10 B.H.P difference from one dino to another
on the same day. They all seem to be set up
different and all swear theirs is right, but
how can they all be right?. Most tuners would
agree a road tune gives 10% power gain and
a fast road tune 25% power gain. A proddy
tune 35% power gain, still more from 2mm oversize
pistons. Remember more power equals less reliability
and more maintenance. The bikes also become
more sensitive to hotter, cooler & damp
days sometimes changing dramatically the way
they perform or not as the case may be, especially
if you have S&B, K&N or similar air
filters.
Information kindly provided by www.rdlccrazy.co.uk.
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