DRI has spent 1000's of hours doing R&D on 2-stroke Engines/Cylinders/Port types designs to MAXIMIZE PERFORMANCE and RELIABILITY . There are no quick read manuals to explain the complexity of 2-Stroke porting.
Data must be gathered-recorded and analyzed, to help properly design cylinders that not only perform properly but give the reliability and consistency expected from DR/PTR Cylinder.

• DRI has proven port designs for ALL Applications; Desert, MX, XC,  Off-Road, Sand Dunes and Sand Drags, Ice Racing, Enduros, Serious Trail Riding, etc.  You name it DR has built cylinders that have raced it.

• DRIs have won more Pro ATV Races and Pro ATV Championships than any other company in the world over the last 4 decades. DRI has spent 100's of hours  doing R&D on 2-stroke port cylinder port designs

• All port work is 100% Guaranteed

• All PTR cylinders have port timing degreed in and all port dimensions are blued and scribed for MAXIMUM consistency

• PTR Porting is a labor service modification

• All PTR porting is performed in house. By Loren Duncan

• All PTR ported cylinders and individually serial numbered. With data recorded in a DRI data file, for future reference

• For Maximum performance and reliability with a PTR ported cylinder it is imperative the piston, rings and cylinder bore are kept good conditions.
  Piston clearance should ALWAYS be kept under .005 of an inch * Contact DRI for more details

• Quality Cylinder Boring and Proper Port Chamfering is critical to the performance and reliability of your cylinder.
  When these services are required for your engine, be sure that they are performed by DRI or a highly trained technician

• Call DRI for one on one consultation about, your machine, your riding and your needs. #619.258.6306

• Paul Turner Racing Products are a proprietary brand of Duncan Racing International, Inc.
  Honda TRX 250R Porting Type Options
  NATIONAL Cross Country (low end)
  NATIONAL Midrange (midrange)
  ELIMINATOR (midrange/top end combo)
  HIGH REV (top end)
  

• All PTR porting types same price.
  PTR Porting and Stock Head Rechambering $595.00
  PTR Porting (use Powerhead at additional cost) $595.00
  Powerhead without headstay$299.00
  *If customer already has a Powerhead, they may purchase a matched dome(for ported cylinder)for $49.95 and use their existing Powerhead outer shell.
  
  *Cylinder Boring and Pistons are not included in porting prices. DRI offers in house cylinder boring/honing and a complete line of pistons Available at additional cost
  
  CR 250-HPP Cylinder Conversion. DR still offers the CR to ATC/TRX engine conversion. Call DR for more details.
  
  Models
  Fits:
  Honda TRX 250R 86-89
  Honda ATC 250R 85-86
  
  Cores Required
  Cylinders and Head(if stock head modification is desired)
  Customer must send in their cylinder for PTR Port modification or purchase new/used cylinders direct from DRI. Subject to availability

REED CAGE RECOMMENDATION: Pyramid Reed Valve with no reed spacer.

Power Emphasis
NATIONAL XC:Power emphasis very Strong Bottom and Good Midrange Pull
Best Carburetor:36mm PJ Keihin, 38mm PWK
Best PTR Pipe:Type 6 or Midrange RACE Pipe, ELIMINATOR Pipe
NATIONALMidrange:Good low end throttle response, excellant midrange, good top end,
likes to pull a taller gear
Best Carburetor:36mm PJ Keihin or 39mm PWK Keihin
Best PTR Pipe:Type 6 or Midrange
ELIMINATOR:Power emphasis; good Bottom end Strong Midrange Pull, Very Good Top End.
Strongest Power at 3/4 throttle
Best Carburetor:36mm PJ Keihin or 39mm PWK Keihin
Best PTR Pipe: Midrange RACE, Eliminator, High Rev
HIGH REV Kit: Fair low end throttle response, Good midrange, excellant top end,
Revs out Very Well
Best Carburetor:39mm PWK Keihin
Best PTR Pipe:High Rev or Eliminator

Power Gain
20-25% over stock, peak

Reliability Rating
With proper maintenance, PTR Porting is 85% reliable as stock

Application Recommendation
XC/Low End: Cross Counrty/Tight Woods Riding and or Racing
Midrange: Motocross, Sand Dune Riding, Trail Riding, Gran Prix Races,
*Best Overall PowerBand
ELIMINATOR: Excellant Dual Sport type riding, Motocross, Trails, Sand Dunes,
Very Versatile
HIGH REV: Drag Racing, Hill Racing, large TT's and Flat Tracks