Poor Starting After Mods

[evolution12c]

Hi, I hope someone may be able to help me. I have a 1993 evo, I have recently had the heads reworked, to include a 5 angle valve cut. I also fit a Mikuni Hsr 42 at the same time, I run crane single fire and an ev27 cam. The problem i have had is since this work it takes a long time to start. when it does start it coughs and splutters for a couple of minutes and then it is perfect for the rest of the day. I am really pleased with the way it rides and the performance I have gained. I had to retard the ignition as I was getting alot of pinging, this has settled although it does still ping slightly when hot.Does anyone have any ideas, not sure to look at head work, carb or just the tuning. one thing I have noticed is the choke only comes out eighth of an inch with the mikuni.is this normal.any help would be appreciated.

[econnor]

1/8" is not normal. I would start by investigating that choke issue. After that you should confirm timing with a timing light and optimize all of the settings on that Carane Hi-4. And then the jetting, do a search here first for other Mikuni tuning combos and compare to yours. Make small changes each time.

[rcsoftail]

As mentioned by Econnor, 1/8" is not normal. Did you follow the instructions for the replacing the choke plunger at the end of the choke cable with the mikuni plunger? Also, you should have a 25 pilot jet with the pilot air screw turned out 2 turns. I would also static time your ignition and set the slope to 5 to start with.

Choke cable instructions.
1. Remove the stock Harley choke
cable assembly.
2. Remove the spring and plunger
from the stock cable.
3. Remove the Mikuni “Starter Nut”
from the HSR.
4. Remove the Mikuni spring and
plunger from the HSR.
5. Install the Mikuni spring and
plunger on the Harley choke cable.
6. Install the Harley choke cable with
the fitted Mikuni spring and plunger
into the HSR carburetor.
DO NOT use the Mikuni Starter
Nut; discard it.
DO NOT use the Harley spring or
plunger; discard them.
Note: If you do not have installation
instructions, you may download them
from the “www.mikuni.com” website
in the “manuals” section.
If the Mikuni Starter Nut is fitted to
the Harley cable, the choke plunger
is held off its seat and the choke is
open all the time. If the Harley spring
and plunger are used, the plunger
does not seal and the choke is
open all the time. The result, in both
cases, is very poor fuel mileage (30
mpg or less).

[ripsass]

Yes that IS normal on Mikini's. It's not a CHOKE, it's an enrichener circuit.
That's all the movement it takes to move the little plunger inside that diverts the extra fuel.

Though on mine it's more like 3/16"-1/4" of travel, but very little compared to a choke.

If you haven't already been running 93 octane, do that. It will allow you to run a little more timing advance without pinging. that will make it start easier/quicker.

Since making these changes your starting routine will be different now too.

What was once 1-2 twists of the throttle for a cold start may now be 3-4, or vice-versa... Try different things til you figure it out again.