Honda TRX 250 National & Eliminator Assembly Kit Tips

1986-1989 Models

SPECIAL NOTE: DRI does not recommend working on the engine of your Honda TRX 250R without the assistance of the Genuine OEM Honda Service Manual.

ASSEMBLY: It is strongly recommended to follow all instructions in OEM Honda Service Manual, specifically for torque values.
Also consult the DRI Tech Sheet for 2-Stroke Top End Assembly.

PRESSURE TEST: All reassembled 2-Stroke engines must be pressure tested to ensure correct operation. For more information, please consult the DRI Tech Sheet for 2-Stroke Pressure Testing.

BREAK-IN: Read and follow instructions for DRI TECH Sheet 2-Stroke Engine Break In.
*NOTE: Engine will run better after it has 3-5 hours on it.

PISTON RINGS: Piston ring installation is a very delicate procedure and should be performed by a trained professional. Always install rings with trademark facing UP. All rings MUST have gap checked. Gap should be .015” to .020”.

SPARK PLUG: Use NGK BR9EIX Gap: .028”
Champion N6YC Gap: .028”
*NOTE: Do not use 8 heat range plugs.

IR INTAKE: DRI recommends using a K&N Filter with Outerwear. For best performance it is recommended to use stock air box with lid removed and stock snorkel hooked up, On ’87-’89 models retain the resonator. See DRI Tech Sheet for Air Filters for proper air filter maintenance instructions. Install Outerwear dry. Do not oil Outerwear. Only oil the K&N filter.

EXHAUST: For maximum performance use a Paul Turner 2-Stroke Pipe and Fat Boy 2 Silencer.
PTR Midrange “RACE” Pipe applications include Dune Riding, MX, XC and Trail Riding. Midrange pipes have a great pull from ¼ to ¾ throttle.
PTR ELIMINATOR Pipe applications include Aggressive Dune Riding, MX, Aggressive Trail Riding. Eliminator pipe has strongest pull from 3/8 to 7/8 throttle
PTR High Rev Pipe applications include Sand Drags, Hill Racing, TT and Oval Track. High Rev pipe have a great pull from ½ to full throttle.
Make sure silencers are freshly packed and cores are installed properly. Only use genuine Fat Boy 2 packing. Consult PTR TRX 250R Pipes Instruction Sheet for installation instructions and additional information.

FUEL: Use VP C-12 Fuel. Motor Octane 108 or Sonoco STD with motor octane of 105

TRANSMISSION OIL: Maxima MTL Endurance 85 WT
*Consult Honda OEM Service Manual for oil capacity specifications.

PREMIX OIL Maxima 927. Mix at 32:1 (4oz per Gallon).
In conditions where temperature is below 40° use Maxima Super M or Maxima K2.

CARBURETION/INTAKE: It is recommended when installing these engine kits to upgrade the carburetion. DRI recommends either a Keihin 36mm PJ, 37.3mm PJ, 38mm PWK or a 39mm PWK Carburetor. DO NOT use reed spacers.

REED CAGE: It is recommended to use a PYRAMID Reed Valve with OEM Intake manifold. DO NOT use reed spacers.

JETTING: Consult DRI Tech Sheet for Keihin Carburetor Jetting for information on how to properly set Keihin Carburetors.

TOP END SERVIC
For maximum performance top end should be serviced at least every 20 hours. For standard usage top end should be serviced at least every 50 hours.
A top end service includes checking pistons, reed valves, piston to cylinder clearance, etc.
Piston clearance should be kept between .0025” and .004”. Not to exceed .005”

CRANKSHAFT: For Hi Performance use an OEM crankshaft with stock OEM rod should be used for best reliability.

GEARING: OEM Gearing 14/38(39), Dune Riding 13/38, Hill Racing 12/38, MX Racing 15/38-40, High Speed 15x36-38.

IGNITION: Stock ignition is adequate for most applications. But it should be checked that it is producing proper power output. (As stators become older or get exposed to moisture they tend too weaken power output, causing engine to perform improperly)
However, a flywheel modification is recommended for better performance and reliability in Hi Revving applications like TT’s Ovals and Drag Racing.
DRI also offers the Vortex X10 CDI unit, see website for details

CLUTCH: The clutch must be kept in excellent condition and properly adjusted for maximum performance to be delivered. DRI recommends using a Hinson billet clutch basket and DR C12 Clutch Kit. Make sure that an ’89 Lifter Kit is used to upgrade ’86-’88 model machines.
Call DR Tech department with any questions regarding clutch performance or upgrades.

NOTES
1. Squish clearance should be checked. Piston to head squish should be minimum .040”

DRI is not responsible for any engine component (gears, rod, etc.) fatigue or failure due to increased horsepower and torque.