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AMRA S&S MK136 Challenge Class
S&S Cycle × AMRA | 2027 Race Season

MK136 Challenge Class

Built for speed. Engineered for competition. A dedicated challenge class for racers running the S&S MK136 platform.

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Proven Performance   /   MK136 Engine Platform   /   AMRA Challenge Class
Since 1958

Driven by the pursuit of speed.

From our start in 1958 S&S Cycle has always been driven by an unrelenting passion for speed, power, and engineering excellence. Building on that, the MK136 platform represents the next chapter—delivering unmatched reliability, power, and competitive performance for today’s racers.

With this in mind, S&S Cycle and the AMRA are introducing the MK136 Challenge Class.

Drag race motorcycles on the stripDrag racing track and scoreboards
Competition requirements

MK136 Class Rules

The MK136 Challenge Class is built around a defined, street-legal motorcycle platform. Here’s what you need to know about the class:

  • Street legal motorcycle with VIN
  • Bagger or Softail chassis
  • Single S&S MK136 engine
  • Pro Tree
  • Maximum 64-inch wheelbase
  • 4.320-inch bore x 4-5/8-inch stroke
  • Maximum overbore of .010 inch
  • Major castings to remain S&S, including crankcases, cylinders, and cylinder heads
  • Custom porting permitted while preserving the stock factory port shape, location, and opening sizes
  • Naturally aspirated
  • Fuel: Gasoline, Race Fuel, E85 only. Nitromethane, propylene oxide, and alcohol are prohibited
  • EFI or carburetion permitted
  • No wheelie bar
  • DOT tire
  • Full charging system
  • Self-starting
  • Foot shift, with shift kill permitted
  • Hand clutch
  • Lock-up clutches, slider clutches, and aftermarket clutch-assist mechanisms prohibited
2027 Race Season

Competitor Incentives

To help support racers get started in this class, the incentive plan outlined below will be in place for the 2027 season.

$1,500

Five-event product credit

For the first 16 eligible racers competing in at least five 2027 AMRA MK136 events.

+$2,000

Six-event product credit

Additional S&S product credit for any competitor racing all six scheduled events.

MK136

Champion engine award

One S&S MK136 engine or S&S product credit equal to its MSRP, plus a $1,000 cash championship bonus.

Early Commitment

2027 Entry Fee Incentive

S&S will cover the 2027 AMRA MK136 class entry fees for competitors who register and commit to competing in the MK136 Challenge Class during the Rockingham event on October 17–18, 2026. This incentive applies to MK136 class entry fees for the 2027 AMRA season and is subject to racer and motorcycle eligibility under applicable AMRA MK136 class rules.

Five-Event Participation

$2,500 S&S Product Credit

The first sixteen (16) eligible competitors who compete in the MK136 Challenge Class at a minimum of five (5) 2027 AMRA events will each receive a $2,500 S&S product credit. All product credits awarded will be redeemed at S&S Manufacturer’s Suggested Retail Price (“MSRP”).

Six-Event Participation

Additional $1,000 Credit

Any competitor who competes in the MK136 Challenge Class at all six (6) scheduled 2027 AMRA events will receive an additional $1,000 S&S product credit.

Race Contingency

Winner / Runner Up

$500 race winner / $250 runner up contingency for the MK136 Challenge Class.

Championship Award

MK136 Engine + $1,000 Cash

The 2027 AMRA MK136 Challenge Class champion will receive one (1) S&S MK136 engine as the championship award. The MK136 engine award may be exchanged for S&S product credit equal to the MSRP of the MK136 engine. The 2027 AMRA MK136 Class Champion will also receive $1,000 cash as a championship bonus.

Beyond the starting line

Additional S&S Support

Backing racers and fans throughout the AMRA race season.

Class Sponsorship

Pro Eliminator & Street Bagger

  • $500 race winner / $250 runner up contingency
  • $1,000 Championship Bonus
Trackside

S&S Display Truck

  • At all events
  • Product display
  • Apparel and parts sales
  • Race part support on site
Spectator Experience

S&S Hole Shot Challenge

Test your reaction time at the S&S display with mock drag bikes and a real start tree.

  • Targeted at spectator engagement
  • At each event S&S will host a competition for spectators and reward the winners with product credit certificates
S&S Racing Hardware

Key H-D® M8 Products

Engine components and performance hardware featured in the AMRA MK136 Challenge Class

Explore S&S Cycle →

S&S MK136 engine product photograph
310-1289MK136 Black Edition Engine With 550G Cam for Oil-Cooled 2017-Up M8 Touring
310-1341Crankcase, Assembly, 4-1/2” Bore, Stock Drive Bearing, Packaged, MB Code, Black, 2017-up M8 Touring
310-1351Crankcase, Assembly, 4-1/2” Bore, Stock Drive Bearing, Packaged, MM Code, Black, 2018-up M8 Softail®
900-1186Breather, Kit, CARB EO# D-355-57, 2017-up M8
310-1203Jet, Kit, Piston Cooling, 2017-up M8, US Patent #11927127
560-0360Ramp, Compensator, Lasered and Packaged, 2017-up M8
920-0163Piston, Set, 4.320” x 4.500” and 4.625”, Standard, +8.5cc Dome, HC, w/ Wristpin & Keepers, 2017-up M8 Models
920-0162Piston, Set, 4.320” x 4.500” and 4.625”, Standard, 0.0cc Dome, HC, w/ Wristpin & Keepers, 2017-up M8
170-0832Induction, Kit, Throttle by Wire, 68mm, Throttle Hog, 2017-up M8, except Oval Port
900-1006Head Bolt, Kit, 2017-up M8
310-1204Stud, Cylinder Base, 7/16-14 UNC x 6.250”, Black, Steel, 2017-up M8 Models, 8 Pack
500-1910Bolt, Kit, Pinion Shaft and Camshaft, 1999-2017 bt, 2017-up M8
310-0939APlate, Kit, Cam Support, 2017-up M8 Models
310-0959AOil Pump, Kit, Oil Cooled, 2017-up M8 Models
Ready for the tree?

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