.21XZ-M Speed

21XZ-M Speed Inboard Marine Engine

Get your racing boat up to Speed!

It's O.S.'s first marine engine under the Speed name, and is designed to deliver the same race-winning performance. Factory tuning optimizes the 21XZ-M's power potential, and it also shares the 21XZ-R's big-bore carb, black anodized crankcase and laser-etched, water-cooled head.


21D big-bore carburetor
21D big-bore carburetor
Water-cooled cylinder head with special laser markings
Water-cooled cylinder head with special laser markings
  • Specifications
  • Parts Listing
  • Accessories
Stock Number: OSMG1622
Displacement: 0.213 cu in (3.49 cc)
Bore: 0.641 in (16.27 mm)
Stroke: 0.661 in (16.8 mm)
Practical RPM: 4,000-45,000
Output: 2.8 ps/2.76 hp @ 33,000 rpm
Weight: 10.85 oz (307.5 g)
Includes: 21D carb, RP7 turbo plug, exhaust seal ring, head gasket set, dust cap set
Requires: 10-30% nitro boat fuel (20% recommended for break-in), exhaust system, glow plug igniter

Primary Accessories

Stock Number Mfr Number Product Description Quantity Needed
 AQUP2230   AQUP2230  AquaCraft GrimRacer 30% Boat Fuel Quart 1

Field Equipment

Stock Number Mfr Number Product Description Quantity Needed
 DTXP0310   DTXP0310  Duratrax Ultimate Glo-Starter C 1
 HCAP3001   HCAP3001  Hobbico After Run Engine Oil 2 Fl Oz 1

Optional Accessories

Stock Number Mfr Number Product Description Quantity Needed
 AQUB6903   AQUB6903  AquaCraft Fuel Tubing Green 3' 1
 AQUB9715   AQUB9715  AquaCraft GrimRacer 40x53 Copper-Beryllium Ti Prop 1
 AQUB9720   AQUB9720  AquaCraft GrimRacer 40x52 3-Blade Copper-Beryllium Prop 1
 OSMG2703   71642060  O.S. RP6 Turbo Glow Plug Medium On-Road 1
 OSMG2715   71642080  O.S. RP8 Turbo Glow Plug On-Road Cold 1
 OSMG5872   72403050  O.S. Super Can Filter Large 1
 OSMG8876   72106300  O.S. Exhaust Coupler 21 1
 OSMG9401   55500002  O.S. Lock Washer 3mm 1
 OSMR2976   71521000  O.S. Long Socket Wrench With Plug Grip 1
 OSMR2977   71520100  O.S. Speed Plug Wrench 1
 OSMR3000   71410000  O.S. 10-Piece Speed Driver Tool Set 1