V-Twin Sport Club

the yosh box

plugs in to a socket on the harness of the bike and is used to change the ECU fuel settings .

The box has a comprehensive manual on how to make the changes so I won't be covering that

just how to tune your bike with it.

plug in the yosh and follow the instructions to set the idle mixture.

Set the idle mixture for both cylinders to 0%

Set the low range to 0%

repeat this for mid and upper ranges.

Set the TPS and balance the throttle bodies.

If you have an S set the air screws as per the manual.

warm the bike till its over 82C or 180 F

stop the bike and set the idle mix on the front cylinder to +2%.

restart the bike and check
) the idle note.
) the quality of the rise in RPM as you SLOWLY open the throttle a fraction

reset the idle mix to 4% and repeat the exercise.

then 6%.

keep going till you are aware there is no improvement, choose the best setting. you can use any value 2, 4, and 6 are just starting examples

keep testing the idle rise till you have the best idle and cleanest rise and keep this setting.

Write it down , you'll forget it otherwise. you'l need it later

repeat for rear cylinder....

Test ride bike

check the quality of the bike on closed throttle and just open .
the running and the transition period as you open the throttle.

set the yosh box to low range and set the ECU to +5%.

test ride the bike you are looking for the riding quality of the bike at 1/4 throttle.
check the transition from idle thru to quarter throttle.

set the low range to 10% and ride the bike

evaluate the transition etc.

unless you have lots of mods then you will probably want to go back to 5% cos at 10% the bike will probably be too rich and will be fluffy and stumble.

so settle on a %age and go back to the woekshop.

reset the yosh to idle

and trim the front cylinder again to get the best idle and transition.

then the rear.

test ride the bike.

continue with these till you get the best and SMOOTHEST response up to quarter throttle.

remember to write down your settings as you go.

now put set the midrange to +5% .

put the yosh box in you backpack and go for a ride.........

you need a place to move thru 1/4 to 3/4 throttle

evaluate the running.

change it to 10% and evaluate it (15% if you arent sure )

pick the best one .

now do the upper range.

because so little time is actually up here it is most likely you can just make it the same value as the mid range.

test ride the bike and evaluate every range i have mentioned so for and the transition thruout the whole throttle .

Each one affects the other so the trick is to pick the best value as it rides and interacts with the next one.

I'm assuming in all of this that your bike is going to want + changes.

It is also very likely that the idle mix may not need change or may even be better in the minus

Never make assumptions .....go with what works ...........that is what tuning is all about.....its not about anything you 've seen on someone elses bike.......its what is right for yours.........and you get there by trial, error , testing, evaluating and correcting till you reach an optimum group of settings.