Mount a Suzuki outboard so the anti-cavitation plate sits 0 to 25 mm (0 to 1 in) below the bottom of the boat with the motor fully down, bolt it through the transom (the manual says the motor may come off if it is held only by the clamp screws), torque the transom nuts to the figure for your family, and re-torque them after the 10-hour break-in. The one exception on plate height is the DF300B/350A, where Suzuki says the plate is aligned with the boat bottom or slightly above it.
Everything below is from Suzuki's set-up (installation) and owner's manuals. The DF40A/50A/60A owner's manual says Suzuki strongly recommends dealer installation of the motor, controls and gauges; this page lets you check the numbers and do the portables properly. Never install a motor with more horsepower than the boat manufacturer's recommended maximum.
Measure the transom first
Suzuki measures transom height with a straightedge against the boat bottom extended out past the transom, then a second straightedge from the top of the transom down to that line at 90°. Our post on measuring for shaft length walks through it. S is the 15 in type, L the 20 in, X the 25 in and XX the 30 in; the mm figures vary slightly by family.
| Family (manual) | S | L | X / XX |
|---|---|---|---|
| DF2.5 (service manual) | 435 mm (15 in type) | — | — |
| DF4A/DF6A (set-up manual, 2017 model) | 441 mm (17.4 in) | 568 mm (22.4 in) | — |
| DF8A/DF9.9A (set-up manual, 2010 model) | 422 mm (16.6 in) | 549 mm (21.6 in) | — |
| DF9.9B/DF15A/DF20A (set-up manual, 2013) | 422 mm (16.6 in) tiller and R; T models 427 mm (16.8 in) | 549 mm (21.6 in); T models 554 mm (21.8 in) | Service manual lists X 680 mm (25 in type) for DF9.9BT/BTH |
| DF25A/DF30A (set-up manual, 2014) | 422 mm (16.6 in) | 549 mm (21.6 in) | — |
| DF40A/DF50A/DF60A (set-up manual, 2022) | 403 mm (15.9 in) DF40AST/DF60AT; 401 mm (15.8 in) DF40AT/DF50AT | 524 mm (20.6 in) DF40AST/DF60AT; 522 mm (20.6 in) DF40AT/DF50AT, DF40ATH/DF50ATH/DF60AQH; 525 mm (20.7 in) AV | X 651 mm (25.6 in) DF40AST/DF60AT; 649 mm (25.6 in) DF40ATH/DF50ATH/DF60AQH; 636 mm (25.0 in) AV |
| DF70A/DF80A/DF90A/DF100B (set-up manual, 2020) | — | 511 mm (20 in); DF90AWQH 514 mm (20.2 in) | X 638 mm (25 in); DF90AWQH 641 mm (25.2 in) |
| DF100A/DF115A/DF140A (service manual) | — | 534 mm (20 in type) | X 661 mm (25 in type) |
| DF100C/DF115B/DF140B (set-up manual, 2022) | — | 20 in shaft; drawing 534 mm (21.0 in) | X 25 in shaft; drawing 661 mm (26.0 in) |
| DF150A/DF175A/DF200A (set-up manual, 2022) | — | 20 in shaft | X 25 in shaft |
| DF150AP/DF175AP/DF200AP (set-up manual, 2022) | — | 20 in shaft | X 25 in, XX 30 in shaft |
| DF250AP/DF300AP (set-up manual, 2021) | — | 508 mm (20 in) | X 635 mm (25 in), XX 762 mm (30 in) |
| DF300B/DF350A (set-up manual, 2022) | — | MD (integrated steering) drawing only: 20 in label | X 25 in, XX 30 in shaft |
Suzuki's own documents differ by a millimeter or two: the DF4/5/6 service manual prints 442 mm (15 in type) and 569 mm (20 in type), and the DF9.9B/15A/20A service manual prints 426 and 553 mm for the T models. Use the shaft type.
Find the center line
Measure across the transom from chine to chine and mark the transom face at half that measurement; the set-up manuals repeat this strake to strake and join the two marks with a straightedge. A motor that is not accurately centered will make the boat pull to one side. Minimum twin-engine center-line spacing: 558 mm (22 in) on the DF40A to DF60A (marks 279 mm / 11 in each side of center), 635 mm (25 in) on the DF100C/115B/140B (317.5 mm / 12.5 in each side), 686 mm (27 in) on the DF150A and up (343 mm / 13.5 in each side).
Clamp screws and bolts: use both
On the DF4A/6A, DF8A/9.9A, DF9.9B/15A/20A and DF25A/30A: center the motor and secure it by alternately tightening the clamp bracket screws by hand, then install the bolts, washers, lock washers and nuts through the transom, tighten them sequentially and seal the holes with sealant. The owner's manuals put it bluntly: be sure to bolt the motor to the transom; the motor may come off if it is held only by the clamp screws. The label on the bracket says the same. Over-tightening the transom bolts can damage the clamp bracket; no impact tool on the transom nuts. The DF4A/6A set-up manual notes the transom bolts are not included with the motor.
The DF2.5 has no bolt holes: clamp screws by hand, then a sturdy rope or cable between the boat and the hole in the clamp bracket for security.
From the DF40A up there are no clamp screws. The motor must be secured with four mounting bolts, flat washers and lock nuts; six on the DF300B/350A, and Suzuki highly recommends six on the DF150A and up for rigid-hull inflatables or similar.
Anti-cavitation plate position
With the motor lowered all the way down, the anti-cavitation (anti-ventilation) plate should be 0 to 25 mm (0 to 1.0 in) below the bottom of the boat on every family from the DF2.5 to the DF250AP/300AP (the DF150A and DF250AP manuals print 0 to 2.5 cm). On the DF300B/350A the plate is aligned with the boat bottom or slightly above it. On a step hull the plate may sit higher than the boat bottom; the larger set-up manuals add that the best height depends on the boat and motor combination and test runs at different heights can settle it.
Too high, and the propeller slips, wasting power or overheating the motor; too low increases drag and reduces speed. Do not run with the plate above the water; the DF2.5 manual says it can cause overheating and severe damage.
Bolt kit, drill size and torque by family
| Family | Clamp screws | Bolt kit | Holes | Torque |
|---|---|---|---|---|
| DF4A/DF6A | 2, M10 x 1.5 | 2 x M8 x 90 (09100-08311), washers 09160-08081, lock washers 29162-93J10, nuts 09140-08023-XC0; not supplied | 2 holes, 9 mm (spacing per the set-up manual drawing) | 13 N·m (9.5 lb-ft) |
| DF8A/DF9.9A | 2, M14 x 2.0 | 2 x M8 x 90 (09100-08239), washers 41154-91J00, lock washers 29162-93J10, nuts 09140-08016, caps 41153-96300 | 2 holes, 9 mm | 13 N·m (9.5 lb-ft) |
| DF9.9B/DF15A/DF20A | 2, M14 x 2.0 | 2 x M8 x 90 (09100-08311), washers 41154-91J00 and 09160-08170, lock washers 29162-93J10, nuts 09140-08016 | Tiller and R: 4 holes, 9 mm; T/TH: 3 holes, 9 mm (patterns per the set-up manual drawing) | 13 N·m (9.5 lb-ft) |
| DF25A/DF30A tiller and R | 2, M14 x 2.0 | 2 x M10 x 110 (09100-10309), washers 09160-10139 (35 mm) and 09160-10140 (18 mm), nuts 09159-10050 | 4 holes, 10.5 mm | 38 N·m (27.5 lb-ft) |
| DF25A/DF30A T, TH and Q | — | 4 x M12 x 100 (09100-12093) with washers and nuts 09159-12014 | 12 mm drill; upper holes 25 mm (1 in) or more below the transom top | 55 N·m (40 lb-ft); re-torque after the 10-hour break-in |
| DF40A/DF50A/DF60A | — | 4 x M12 x 100 (09100-12093), nuts 09159-12014; optional 115 mm bolt 09100-12091 | 12 mm drill; upper holes 25.4 mm (1.0 in) or more below the transom top | 55 N·m (5.6 kgf-m, 41 lbf-ft) |
| DF70A/DF80A/DF90A/DF100B | — | 4 x M12 (09100-12127), nuts 09159-12014 | 12 mm drill; upper holes 25 mm (1 in) or more below the transom top | 55 N·m (5.6 kgf-m, 41 lbf-ft) |
| DF115A/DF140A | — | 4 x M12 x 115 (09100-12091), nuts 09159-12014 | 12 mm drill; upper holes 25 mm (1 in) or more below the transom top | 55 N·m (5.5 kgf-m, 40 lb-ft) |
| DF100C/DF115B/DF140B | — | 4 x M12 x 115 (09100-12091; DF115BS 09100-12127) for transoms 40 to 79 mm (1.6 to 3.1 in); 150 mm bolt 09100-12090 for 79 to 114 mm (3.1 to 4.5 in); nuts 09159-12014 | 12 mm drill; upper holes 25.4 mm (1.0 in) or more below the transom top | 55 N·m (5.6 kgf-m, 41 lbf-ft) |
| DF150A/DF175A/DF200A and DF150AP/175AP/200AP | — | 6 x 1/2-20 UNF x 150 mm (09100-12086) with OD 45 mm and OD 26 mm washers, two-hole washers 41155-93J02 and nylon-insert lock nuts 09159-12062 | Upper holes 25 mm (1.0 in) or more below the transom top; 165 mm (6.5 in) between the second and lower bolts; drill size not stated (bolt is 12.7 mm / 1/2 in) | 80 N·m, printed as 8.0 kgf-m, 58.0 lbf-ft on one page and 8.2 kgf-m, 59 lbf-ft on another |
| DF250AP/DF300AP | — | Same 09100-12086 kit, six bolts | Upper holes 25.4 mm (1.0 in) or more below the transom top; 165 mm (6.5 in) between second and lower bolts | 80 N·m (8.2 kgf-m, 59 lbf-ft); also printed 8.0 kgf-m, 58.0 lb-ft |
| DF300B/DF350A | — | Same 09100-12086 kit, six bolts required; optional 09100-12125 (170 mm) and 09100-12126 (190 mm) | As DF250AP/300AP | 80 N·m (8.2 kgf-m, 59 lbf-ft) |
Install the bolts with the large flat washers from inside the transom and through the clamp brackets, fit the small washers and nuts on the bracket side, then tighten all nuts to the specified torque; on the DF150A and up, hold the bolt and turn the nut, and the four-bolt method is allowed only with a transom reinforcement plate between the large washer and the transom. Use only genuine Suzuki mounting hardware. More figures are on the torque spec chart.
Rules that apply to every bolt-through install
- Drill all holes perpendicular (90°) to the transom, and never drill the top holes higher than 25.4 mm (1 in) below the top edge of the actual transom.
- Sealant (Suzuki Silicone Seal or equivalent) goes in all bolt holes and on the bolt shanks, not the threads: a thin layer inside the whole hole with a thin stick, then sealant on the shank before inserting the bolt. Take care with the lower clamp-bracket bolt when it sits below the waterline.
- No impact wrench or tool on the transom nuts; it risks thread damage and a wrong torque.
- Never reuse a lock nut after it has been threaded into position and torqued.
- The transom face must be flat so the clamp bracket makes full contact; any clearance at the mating surfaces can damage the brackets. The brackets must not sit on the gunwale molding or transom cap. If there is a gap at the transom top, fit a proper spacer so the motor's weight is carried through it.
- No wedges or non-metallic plate between the clamp bracket and the transom; if a plate is needed, only a metal plate, never wedges even if metal. If the transom is too weak to reach the specified torque, a reinforcement plate may be needed between the transom surface and the large washer.
- The transom bolt must not be exposed from the transom surface, and do not hang accessories on the engine mounting bolts.
- Lift with a hoist of at least 450 kg (1000 lb) capacity, by the lifting eye only, never a flywheel lifting attachment; the DF9.9B/15A/20A manual gives the same 450 kg and lifting eye 11291-91B50.
After the first 10 hours
After completing the 10-hour break-in, retighten the transom nuts to the specified torque, then check them periodically. On the portables, keep checking the clamp screws; "engine mounting bolts or clamp screws are loose" is the first cause the owner's manuals list for excessive vibration. When trailering, never use the tilt lock to hold the motor up; use a transom saver bar or similar to support its weight.
Controls and steering
Rigging a remote motor means measuring the cable run before ordering: see how to measure control cables. The DF8A/9.9A set-up manual lists control cables 67320-93J00 (8 ft) through 67320-93J80 (24 ft) in 2 ft steps. To convert a tiller DF9.9B/15A/20A, use the tiller-to-remote conversion kit. Battery and cable sizing is in the battery cable and wiring guide.
Parts for this job
Transom bolt kits, washers and lock nuts are in Suzuki OEM rigging hardware and fasteners; clamp brackets and screws under engine holders and clamps. We sell complete Suzuki outboards up to 30 hp in the Suzuki outboards collection; motors ship free, and orders over $149 ship free to the lower 48.
Sources: Suzuki set-up manuals 99505-97L00-01E (DF4A/5A/6A), 99505-99J00-01E (DF8A/9.9A), 99505-89L10-01E (DF9.9B/15A/20A), 99505-94L10-01E (DF25A/30A), 99505-88L40-01E, 99505-87L50-01E, 99505-92J20-01E, 99505-99L40-01E, 99505-96L60-01E, 99505-96L70-01E, 99505-98J40-01E, 99505-98L40-01E; Suzuki owner's manuals for DF2.5 (2019), DF4A/6A (2019), DF8A/9.9A (2014), DF9.9B/15A/20A (2020), DF25A/30A (2019), DF40A/50A/60A (2022); Suzuki service manuals 99500-97J01-01E, 99500-91J03-01E, 99500-89L00-01E, 99500-88L01-01E, 99500-87L10-01E, 99500-92J00-01E. Figures are Suzuki's published values; confirm against the manual for your model year and serial number.