Upgrading
the stock exhaust.
Most
Smallframes have a completely useless exhaust, which does nothing
except produce a nice put-put-put sound. The standard exhaust
fitted to the ET3 is actually pretty good. However it's a bitch
to remove when you need to change the rear wheel and for that
reason alone it has to go! If you are kitting your engine then
you will need to upgrade from the standard exhaust to get more
power.
Two-strokes
are quite sensitive to the exhaust because back-pressure is necessary
to help the combustion along. Too little and the engine won't
run well, unburned fuel and fresh air going straight out of the
exhaust. Too much and the engine won't run well either, as burned
exhaust gases suffocate the incoming charge. There's a sweet
middle ground, and most after-market performance exhausts are
designed to maximise the performance within this area.
Most
of the available exhaust are really designed for kitted engines.
They are really designed to remove the bottleneck in performance
that a kitted engine with a stock exhaust has. Some work well
on standard engines too. The Leovinci demonstrated here is one
of those. I chose it on price, easy availability in the UK, and
the fact that it is easy to remove to get at the rear wheel.
It ain't pretty but I ain't rich. The Polini is similar. Other
more expensive examples are made by Simonini, Zirri and PM Tuning.
First
we jack up the scooter on a milk crate pinched from outside a
shop the night before:
.
Then
we remove the ET3 expansion box. Thank god we're never going
to have to put it on again.
First
unbolt the expansion box from the downpipe. You'll need a socket
set and a long extension. After you've done this let all the
air out of the rear
tyre, and use an open ended 17mm spanner to remove the bolt holding the expansion
box to the engine crossmember. It's best to do this from underneath the bike.
Now take the rear wheelrim off. This will make it easier to get at things.
Because the Leovinci slides onto the bolt rather than needing it to be removed
you can put the bolt back now, and re-inflate the tyre.
Other
types of exhaust may need to be bolted through, so you would
need to keep the rear tyre deflated until the new exaust is fitted.
If this is the case I reckon it's a worthwhile modification to
take a hacksaw to the mounting hole and make it into a slot like
the Leovinci's.
I
took the opportunity to take the wheel indoors and clean the
whitewalls with washing up liquid and the bleach. These Sava
MC12s don't discolour like Continentals, and clean up a treat.
I will definitely be buying them again. By the way - notice my
rear wheel does not have it's centre cap? That's because at this
point I was going to replace my rear brakes. However I couldn't
shift the damn hub nut, so a trip to a garage with impact wrench
was needed on another day.
Now
we remove the plastic flywheel / cylinder shroud. This has one
bolt at the side, one self tapping screw in the middle and one
metal screw to the right (all highlighted in the picture). Take
the spark plug out and maybe unclip the lead too to give yourself
a bit more room. Now go back round to the other side of the scooter
and undo one last screw on that side. You can now lift the shroud
out of the way, just enough to get at the bolts. I also unbolted
the rear shock to give myself a bit more room to play with. I
found I was able to wedge the shroud up out of the way.
Now
we take off the downpipe. You'll need an open ended spanner for
the clutch side, but you can use a socket on the flywheel side.
(you can also see the hole where the shroud bolts on this side)
Replace
it with the Leovinci downpipe. Here's mine after fitting.
Replace
the engine shroud. If you haven't already done it, replace the
crossmember bolt. Now replace the rear wheelrim.
Attach
the Leovinci expansion box and partially tighten the crossmember
bolt to hold it there. Here is the expansion box just about to
be slid onto the bolt, along with a very clean rear tyre.
Now
mate the downpipe and the expansion box. You should still have
enough play to do this easily.
I
found the best way to attach the spring to the downpipe was to
use a loop of string to pull it down and through the hook on
the expansion box, then the string can be untied or cut. Keep
a loop in your traveling toolkit just for this purpose.
Now
you can tighten up the frame nut fully - At this point adjust
the fit and position of the expansion box to make sure it does
not rub against the wheel.
There
we are, all done. It's a damn sight louder than the original
part, but seems to produce a little bit more power on acceleration,
perhaps losing some top end. I have been informed that when mated
with a properly ported Polini 130cc kit it really shines. Being
a clone of the Polini pipe that doesn't surprise me.
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