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| AMA | SBK | Difference | |
Homologation | Must be homologated by AMA. Must be street certified in the US and available through US retail dealers. AMA can withhold or withdraw homologation in interests of competition. | Must be mass produced street certified motorcycle. Minimum build of 1000 units (3000 in 2010). Must be equipped with all road equipment at time of FIM Homologation inspection. | No minimum build numbers in AMA. | |
Minimum weight | 4 cylinder 375 pounds. 2 cylinder 390 pounds | 1000cc 2 cylinder – 162kg. 1000cc 3 or 4 cylinder – 162kg (357 pounds). 1200cc 2 cylinder – 168kg (370 pounds) with 50mm air restrictor | AMA bikes heavier - 1000cc by 18 pounds. 1200cc by 20 pounds. SBK 1200 twins restricted. | |
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Bodywork | May be modified or replaced*. Must resemble approved parts in design and dimensions. No carbon composite or carbon fibre. | Must conform in principle to the homologated shape as originally produced by the manufacturer. Material may be changed. | Carbon bodywork ok for SBK? | |
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Wheels | Can be changed*. Must be 17 x 3.5 front. 17 x 6.0 rear | Max width: 4.0” front and 6.25” rear | SBK have wider wheels however both series on control tyres. | |
Brakes | May be modified or replaced.* | May be modified or replaced. | No difference. | |
Front suspension | Original fork inner and outer tubes. Internals can be changed. Fork triple clamps can be changed. | May be modified or replaced. Fork triple clamps can be changed. | SBK can run pure race forks like Ohlins etc. | |
Swingarm | As homologated. Some modifications allowed. Buell chain drive conversion allowed. | May be modified or replaced. | SBK can brace swingarm. I think this means SBK can change wheelbase too. | |
Frame | As homologated. May be braced/strengthened. Must have identification number. (Must have 17 digit production vin from 2010). Steering head inserts to change steering angle allowed. Adjustable swingarm pivot only allowed if featured on homologated frame. | As homologated. May be braced/strengthened. Must have identification number. Steering head inserts to change steering angle allowed. | No difference. | |
Compression Ratio (CR) | Free | Free | No difference however SBK has more options in how CR is changed. | |
Cylinder head | Original. May be modified. Must retain standard valve sizes. | Original. May be modified. Must retain standard valve sizes. | No difference however SBK has more options in how CR is changed. | |
Camshafts | May be modified or replaced. Duration unrestricted but lift unchanged. | May be modified or replaced. | SBK has more freedom. | |
Pistons & rings | Standard or replaced with approved substitute. Approved substitute same weight or more. Standard rings pin etc. | 1000cc – may be altered or replaced. 1200cc 2 cylinder – Standard or piston kit. Piston kit must be freely available for same price as standard. | SBK 1000cc bikes can run any piston. | |
Connecting rods | As homologated. | 1000cc – can modified or replaced. 1200cc 2 cyl – as homologated. | SBK 1000cc bikes can change to race rods and alter length and material. | |
Crankshaft | As homologated. No modifications except oil gallery’s and polishing bearing surfaces. | 1000cc 2 cyl – may be altered or replaced. 1000cc 3 or 4 cyl and 1200cc 2 cyl - As homologated. no modifications except polishing bearing surfaces. | Effectively no difference. | |
Transmission | Transmission as homologated. may be undercut shimmed etc. Final drive ratios can be changed. Can change to chain final drive. Electronic quick shift kits allowed. | Gear ratio’s and primary ratio and final drive is free. Must retain same number of gears. Quick shifters allowed. | SBK able to change gearing to suit track. | |
Clutch | May be modified or replaced*. Must remain same type as homologated (wet or dry). | May be modified or replaced. Must remain same type (wet or dry) and actuation (cable or hyd) as homologated except 1000cc 2-cylinder . | Effectively no difference. |
Airbox | As homologated. internal flaps etc may be removed. All incoming air must pass through the original unmodified airbox inlets. | May be modified or replaced(50mm restrictor for 1200cc twins) | AMA bikes restricted to street bike airbox inlets. SBK able to enlarge airbox and inlets however 1200cc twins still have 50mm restrictor. |
Radiators/Oil coolers | May be modified or replaced.* | May be modified or replaced. | No difference. |
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