This bike was a practically stock 1991 Suzuki Bandit 400, except for a slip-on F1s muffler.
Stock engine, carbs, airbox, jetting, header pipes... all but the exhaust, which is an F1s.
It wasn't running well, idled high, but coulcn't be made to idle lower without stalling, decent, but iffy power.
first settings:
| exhaust | F1s muffler/can with stock headers |
| airbox/filters | Stock |
| pilot jet | 32.5 (stock) |
| main jet | 102.5 (stock) |
| fuel screws | 2 turns out (I think) |
| float height | about 15mm (spec is 14.6 +/- 1.0) |
| thermostat | ~79° C (stock) |
| exhaust | F1s muffler/can with stock headers |
| airbox/filters | Stock |
| pilot jets | 32.5 (stock) |
| main jets | 102.5 (stock) |
| fuel screws | out 2-1/4 turns |
| needles | Factory Pro 1.0 third position |
| float height | 15mm |
| thermostat | from a CBR600F2 (warmer, 87° C I think.) |
What the hell? Why does a larger main jet make the idle work better?
| exhaust | F1s muffler/can with stock headers |
| airbox/filters | Stock |
| pilot jets | stock (32.5) |
| main jets | stock (102.5) |
| fuel screws | out 2-1/2 turns |
| needles | Factory Pro 1.0 2nd position |
| float height | 15mm |
| thermostat | 87° C from a CBR600F2 |
I was having a bear of a time getting it to behave properly at low RPM and learned this lesson:
Check the following things: