Special-purpose Units · part-number series 4246
SP 451, SP 481
12 exploded views, 251 part numbers.
Factory tuning settings
| Idle speed | 2,800 rpm |
| Max speed | 12,500 rpm |
| L screw (low speed) | 1 turn |
| H screw (high speed) | 3/4 turn |
| Confidence | sourced |
Screw figures are turns open from lightly seated. Set the final mixture by ear and tachometer against the machine in front of you — running a two-stroke lean to hit a published number is how pistons get scored.
Parts are not interchangeable across series — check yours before ordering.