Olisit heti sanonut, et sulla on M16 ECU....
Below is some info gathered from the mailing lists, the shop manual, and personal experience. Note that these instructions are for the ST2 with the 16M computer, not sure all of the procedures will apply to the ST4.
Remove the cover on the big connector going into the computer. This is done by removing the zip-tie on the rubber boot, removing the small screw on the end, and then sliding the cover off. The connector must remain attached to the computer. Make sure the fuel pump, etc. are still connected as these loads may affect the readings.
Hook a voltmeter up between pins 16 and 30, set to measure DC voltage.
Turn ignition on, but no need to start engine. Voltage should be in the 500-560mv range according to the shop manual. I have also receive via email a suggestion that US bikes may work better with a reading of 462mv and European bikes may work beter with a reading of 404mv, each +/- 5mv. The same source gave values of 404mv and 345mv for the US and Euro model ST4.
If adjustment is needed, back the throttle stop screws all the way out and check voltage again. Should be 150mv with throttles completely closed. If not, loosen the TPS screws, rotate it to get the desired reading, and re-tighten.
Now turn the stop screw on the throttle body attached to the TPS to open the throttles enough to get the readings specified in step 3 above.
You are now done with the TPS so can remove the voltmeter. Basically the above procedure calibrates the TPS to output a 2.5-3 degree value to the computer at idle. The map on the computer chip is set up to assume the throttles are open 3 degrees at idle and uses the value from the TPS as one of the parameters to decide how much fuel to inject when you open the throttle. From here you need to balance the vacuum on the two intakes via the linkage between the throttles and then fine tune the idle speed with the air bleed screws.