Yamaha
RD LC Tuning
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Gallery | RD250LC
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| YPVS Tuning
If you've never ridden a standard LC before
there can't be many left the experience may
surprise you. The soft lightly dampened forks
bottom under braking so much so a heavy come
down from a wheelie could cause a thump on the
mudguard from the twin banjo under the yoke
. The rear shock is'nt much better. The brakes
are nothing like you're used to on today's bikes.
The engine has little before 6,000rpm then power
seems to double by 7,000 giving a great rush
of speed and adrenaline.
The original swinging arm bushes are crap,
check and replace them .The pads tend to taper
from top to bottom they will tip in the caliper
Ferodo are the best replacements use sinted
pads only . Calipers constantly seize, a good
stripping ,cleaning and lubricating is essential
if you ride hard . You can try this with your
calipers to . Leaving the air box on helps keep
a wider power spread. taking the filter out
makes it a little sharper during the summer.
{all ways do a plug chop after any set up mods}.
Fork Braces reduce fork flex under braking,
Sorry they don't because the problem is the
forks bending backwards just below the bottom
yoke. They also increase unsprung and steered
weight, when in fact you want to reduce it.
A more efficient brace is a stiffer deeper bottom
yoke and a larger diameter wheel spindile. That's
why bikes with TZR or YPVS forks, yokes &
wheels handle so much better .
LC Tuning
TZ big end cages are stronger and have a better
load capacity and will fit. For a tuned motor
the press fit crank center shaft should be welded
and the crank turned to 0.025mm, not the factory's
0.1 However I use 400E web centers .A cheap
way to get more power is to skim the head 0.030in
and raise the exhaust port 1.5mm After market
pipes will do a lot and keep it more reliable
then an outright tune, although some pipes just
move the power up the rev range.
Theys
250lc barrels use 2 TZ O-rings and no head gasket,
notice the rings cut around the liners .not
a common mod .
A good tune on a 250 will give 45BHP with all
the goodies up to 55BHP a 350 can make 70BHP
with all the goodys .You will get around a 15%
power increase with a road tune 25% with a race
tune. More with all the goodys. The goodies
being custom pipes, after market ignition &
big carbs.
The 250LC carbs will give more midrange then
350 or YPVS carbs, worth remembering if your
tune is for midrange . The TZ dry clutch and
gearbox fits in with little trouble .The standard
gearbox is fine with 3 TZ 750 clutch springs
that's all I do .I find the gear box fine to
. A lightened fly wheel is a cheep way to get
500rpm extra and a sharper pick up .It also
gives the crank a longer life, Take of no more
then 6mm. This will however shorten the life
of your fly wheel, keep an eye on it for cracks.
Suspension
Spacers in the fork leg prevent dive and increase
pre load allowing the bike to ride slightly
higher then it otherwise would . This also increases
cornering clearance, Unless the rear is raised
also the steering will get slower and more vague
any after market shock will raise the rear,
a cheep alternative is to put a RD 125LC rear
shock that's what I do . To prevent dive a little
more oil reduces air trapped in the leg making
it build pressure faster under compression.
Stiffer springs are a good things but they are
not just stiffer under braking there stiff all
the time. Heavier oil can help but the damping
will also be heavier all the time , a little
bit more oil and a heavier oil mix is best .
Information kindly provided by
www.rdlccrazy.co.uk.
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