Steve writes:
> I'm going nuts trying to cure this off-idle problem on my 98
KLR. Here's the
> symptom: the transition from a closed throttle position to a
slightly open
> throttle (say 1/8 throttle) is very abrupt. Like turning a
switch on and
> off. This makes it quite tricky to use engine braking
descending a hill as
> the bike wants to lurch forward when I re-apply the throttle.
Likewise,
> rolling the throttle completely off is like hitting the kill
switch.
>
> The bike has stock exhaust with K&N. Dynojet needle on the
third clip.
> Mixture screw out 2 1/2 turns. I've gone all the way down on
the clip and
> have set the mixture screw as much as 3 turns out (maximum
recommended by
> Dynojet) and the symtom remains. The bike otherwise pulls
strong as the
> throttle is opened up.
>
> Any suggestions or should I just try and live with this?
A guess would be that your pilot mixture is too rich. Try setting
the idle mixture screw at 1.5 turns out and see if it's better:
if so you can go down as low as the stock setting of 3/4 and see
whether it gets better still.
A few more data points would be helpful: is your airbox stock or
modified? Did this problem suddenly appear or come on gradually?
Did it by any chance coincide with the re-jetting? Does your bike
require the "Start" (fuel enrichener) lever open to fire from
cold? or does it start fine with the lever closed? Has your float
level ever been checked?
FWIW, excess chain slack will give a sensation something like
this - a "lag" between throttle open and response, accompanied by
a lurch. Don't bother asking me how I know.....
Tom Bowman
Atlanta A14