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Duncan Racing International has professional ported more 2-stroke ATV cylinders to race wins and championships than any company in the world. DR has done extensive testing over the last 40 years to continually offer industry leading port modifications for most sport ATV models and MX Motorcycles. DR offers port designs for a multitude of options to accomadate all types of racing and riding including; MX, Desert, Drag Racing, Flat Track, TT, Ice Racing etc.

DR performs their extensive port modification process on all 2-Stroke cylinders it ports. The process includes

  • Bore-Piston check

  •  Cylinder Length Modification (if necessary to properly set deck height for correct squish clearance)

  • Degreed in port timing

  •  Hand ported by DR Master Technician with over 5000 cylinders ported

  •  Cylinder head rechamber or match with billet head. *anytime exhaust port timing is changed it effects     the engines compression. Thus the need to match any and all ported cylinders with modified head that is matched to cylinder port modifications.

  • DR also offers various other cylinder services that are associated with porting. Including but not limited too; cylinder boring and honing, resleeving, welding, thread repair, surfacing etc.

  •  DR also carries a full selection of top end parts including; pistons, gaskets, bearings etc.

DR offers their world famous “Paul Turner Racing“ to clients around the globe. Client’s ship their top ends (cylinders, heads, pistons) to DR *include Completed DR Work Order Form when sending in your components to DR. DR performs the modifications and returns to client. New modified cylinders are available for some models * inquire to DR for availability.

NOTE: Duncan Racing International is the proud owner of the Paul Turner Racing product line. Including PTR Pipes, Fat Boy 2 Silencers, PTR Porting, Powerheads, Pyramid Reed Valves.
DR signs all 2-Stroke Cylinders with the PAUL TURNER RACING logo

Contact Duncan Racing for more information phone 619.258.6306 , email sales@duncanracing.com