Endurance Rules

Endurance rulebook

The full 2023 Endurance Challenge rulebook can be downloaded in PDF form here:

2023 Endurance Challenge Rulebook 

This should be considered the final and authoritative copy of the NWMM Endurance Challenge rules. In the event of rule differences between the web page and the PDF rulebook, the PDF rulebook will supercede in all cases. PLEASE READ THE RULEBOOK!

Endurance Classes

NorthWest Mini Moto has three championship classes for endurance racing:

Additional classes will depend on rider turnout and interest - please email NorthWest Mini Moto if you would like to propose a new class. NorthWest Mini Moto requires a minimum of 4 teams be entered to race in any new class.

Formula 125 + Scooter

Formula class for four-stroke motorcycles with a displacement of 125cc or less and two-stroke motorcycles with a displacement of 70cc or less, with no chassis and engine modification restrictions, and scooters.

Motorcycle class limits

    a) Unlimited engine and chassis modifications except as noted.

    b) Engine displacement limits:

        ◦ 4-stroke air-cooled: 125cc

        ◦ 4-stroke water cooled: 75cc

        ◦ 2-stroke air-cooled: 80cc

        ◦ 2-stroke water cooled: 50cc

    c) The Benelli TNT 135 is permitted to run in Formula 125 as long as the wet weight of the bike is not less than 250lbs.

Scooter class limits

Three types of scooters, with different displacement limits, are recognized as legal in the Scooter class, each of which has different displacement limits and chassis or engine restrictions:

    a) Vintage air-cooled two-stroke:

        ◦ 225cc maximum displacement

        ◦ Stock-appearing engine cases

        ◦ Frame design must have been first sold prior to 1965. This includes Vespa smallframes, Vespa largeframes and Lambretta Series 1-4.

    b) Modern air-cooled two-stroke:

        ◦ 125cc maximum displacement

    c) Four stroke (any):

        ◦ 190cc maximum displacement

Restrictions for all scooters:

    d) Must use wheels 12” or smaller in diameter.

    e) Must use engine cases that match the original model frame – no motorcycle engine swaps.

    f) Cylinders and heads must be based on OEM scooter cylinders and heads – no motorcycle cylinder/head swaps.

    g) Frame must have been originally sold for street use; no bespoke racing frames.

Except for the restrictions as mentioned above, chassis and engine modifications are open.

Formula Middleweight

Class for medium-displacement minis, with open chassis and engine modifications. Motorcycles that would fit in this class include the YCF F155 SM, Ohvale 160, Kawasaki KX65, Honda CRF150F, Aprilia RS50 with a big bore kit, etc.

    • Unlimited chassis and engine modifications except as noted.

    • Motorcycle engine displacement limits:

        ◦ 2 stroke air cooled: 100cc 

        ◦ 2 stroke water cooled

            ▪ Sportbike frame:     75cc 

            ▪ GP or motard frame:     72cc

        ◦ 4-stroke 4-valve air cooled: 160cc 

        ◦ 4-stroke 2-valve air cooled: 175cc 

        ◦ 4 stroke water cooled:     125cc 

        ◦ Displacement limits may be waived on a case-by-case basis for scooters and older machines. Contact race officials before race day to discuss exceptions.


This is the premier large-displacement class for the NorthWest Mini Moto series.

    • Unlimited chassis and engine modifications except as noted.

    • Engine displacement limits:

        ◦ 4-stroke 2-valve air- or air-oil cooled: 212cc

        ◦ 4-stroke 4-valve air- or air-oil cooled: 190cc

        ◦ 4-stroke water-cooled: 150cc

        ◦ 2-stroke air-cooled: 125cc

        ◦ 2-stroke water-cooled, no powervalve: 105cc

        ◦ 2-stroke water-cooled with powervalve: 100cc

Displacement limits may be extended on a case-by-case basis if power at the rear wheel does not exceed 25HP as certified by team testimony and dyno evidence. Exceptions will be revoked or penalized if unfair advantage is evident during the race. Contact race officials before race day to discuss any exceptions.

Class Examples

Example machines for each class (not comprehensive) are:

    • Formula 125 + Scooter: Honda XR100 with a 120cc kit and an XR80 front wheel, Yamaha TTR-125 small wheel (drum brakes), Yamaha YSR50/60, Honda XR50 with an 88cc kit and front forks with disc brakes, Honda Grom, Kawasaki Z125 Pro, Kymco K-Pipe 125, SSR Razkull 125, Yamaha YSR80, Benelli TNT 135, Aprilia RS50 (stock), Yamaha TTR-125 big wheel (disc brakes), Honda NSR50, Honda NSF100, Piranha SSR 125, Ohvale 110, Aprilia RS50 (modified), Kayo MR125, Honda CBR125, Kawasaki Z125, YCF SM F125, Vespa smallframe, Vespa largeframe, Lambretta series 1-4, Honda Elite, Yamaha BWS.

    • Formula Middleweight: Any year YCF F150/155 SM, Kayo MR150, Kawasaki KX60, Honda NSR50 with 60cc kit, Kawasaki KX65, KTM 65 SX, Honda CRF150F, Chinese YX-engined pitbikes with a 150cc-170cc 2-valve motor (SSR, Pirhana, etc), Ohvale 160, Kawasaki KLX-140, Vespa 100cc 2T scooter, Aprilia RS50 with an overbore, YCF SM-F150

    • Open: Honda CRF150R, CR/YZ 85 up to 105cc (no powervalve), KTM SX/RM85/post-2019 YZ85 with up to 100cc overbore (powervalve), Kawasaki KX100, Ohvale 190, Daytona 4v 190cc motors, Daytona Anima / Zongshen / YX 2-valve motors up to 212cc, Honda CRF230.