A lot of
people on scooter motor forum made thread about "what happen with
my exhaust" or i ever read "my new exhaust is not working well"
i try to help the other riders and scooter motor's users to share about jetting
in general. It's not an exact guideline so there's no responsibility if you
want to try it.
What your
modification style and purpose. Each modification with different style needs
different upjets so i made some general rule to understand it more easily.
I mentioned
from now, 50cc scooter and 125cc scooter is an option,
bore kit or carburetor as the example.
70cc/172cc
Kit: 8-12% upjet result (depend on the kit and gear, some of them need more
upjet over 12%)
Exhaust
equipped: 5-8% upjet result (depends on exhaust performance)
Open Filter
kit: 5-10% upjet needed (depends on setup and tuning)
21mm/25mm
carburetor: 4-6% upjet result (depends on setup and tuning system)
HOW TO JETTING UP CARBURETOR
How to do
upgrade jetting is usual question asked by all riders and scooter motor's
users. Jetting is not only about change the jet, but how to make good result
and performance after jetting.
How To
Jetting Guide
First of
all, before jetting your scooter motor, make sure you drain the
float on the carburetor until it empty. Suck the rest of draining float bowl
with vacumm pipe and push until it start.
To know and
check your jetting is correct, listen to the scooter motor (need practice). If
it produce barrel noise so we can say it running lean. if it running with
duller noise, be happy that your jetting is correct.
Another
method, plug chop and run pull your bike with full throttle then as quick as
you can turn off the scooter motor. Check the color of plug,
white signed for lean, black sign for rich and brown is sign for good jetting.
Important
Note: Check your scooter motor, some scooter and motorcycle use automatic
chokes. You need to open a plug chop before you can do the test above.
So, We
Start From Where?
General for
jetting, scooter motor running rich is much better then running lean.
Lean running will heat your engine and scooter motor or even rise up the risk
of seizure on your scooter motor.
Play
Diagnosis with Jetting
As i
mentioned above, checking your jetting result with sound when running and the
color of your scooter motor plug is not the only way. Feel the reacts of engine
on different throttle level. Less power and performance produced if there's no
rich running.
LATEST
NOTE
Most of
people meet some problem when try to use percentages when share about jetting.
So here the simple answer below.
Standard
Jet: 60
70cc Kit
Added: 12%
New Jet: 67
Use general
rules as your parameter. Always consider what you doing before you change every
roller on your scooter motor.
Exhaust
means to drop a gram on rollers, stiffer on springs
Bigger carburetor means half a gram off rollers, stiffer on
springs
