At 09:22 AM 7/24/2004 -0400, you wrote:
>Listers,
>
>I've got a slight stumble at light throttle cruise. Smooth as glass if
>you punch it, but at steady state part throttle cruise it misses slightly.
>
>Any ideas?
>
>Thanks.
>Scott
I said I wasn't going to do this often, but here I am
again. Actually Scott, you are on the path to tuning you Tiger for optimum
fuel efficiency. Under rapid acceleration, you get a squirt of gas from
the accelerator pump and then the power valve opens keeping the mixture
rich until you back off for cruise. Once your manifold vacuum rises above
the power valve setting, your running on only the primary jets.
The condition you describe typically means that your mixture is
too lean indicating that your jets are a little small. You could install a
power valve with a higher opening setting, but then you'd get very poor
mileage. The term most often used to describe your symptom is
"hunting". Try installing primary jets about 2 sizes larger and see if the
"hunting" go's away. If it doesn't, go a little larger again. The optimum
is to set these jets so that it's smooth all the way as you slowly drop
your manifold vacuum until you get a real surge in power as the power valve
opens.
You also need to check your advance, both mechanical and vacuum,
independently, to make sure your not advancing the spark excessively. Keep
the mechanical portion under 35 degrees and if you have vacuum advance you
can let it go further but limit it so you don't go above about 40 even
under 15 inch vacuum cruise conditions.
Tom Hall
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