250cc Moto-Cross Motor

    The Patriot Racing 250R Moto-cross motor is the result of countless hours of testing and development.  This engine package is equally adept from the tightest to wide-open tracks.  The power output level of this engine makes it very competitive at any level of competition.

Pipe:

    The heart of any good two stroke engine is its pipe.  We've tested many many pipes over the years and have just recently found by far the best pipe.  We use the Eddie Sanders Racing TRX-6 pipe.  This pipe was compared against almost every other MX pipe out there and the ESR TRX-6 pipe was the best of them.  Offering exceptional low end power, a smooth transition "onto the pipe" and an excellent robust top-end pull.

Carb:

    We've tested the spread the of carbs available and found the best performing for most conditions.  We use a Keihin 35mm PWK Airstriker carb.  The PWK D-slide shape and the Airstrikers unique velocity wings provide for excellent throttle response and power.

Reed Cage:

    For our MX motors we use the Boyesen RAD Valve.  The unique RAD valve design works well to provide good mid range sap and good top-end power.

Cylinder Head:

    The 250R head design needs some special attention to net the desired results.  The standard squish band clearance is much too great to be much of any benefit.  The squish band clearance must be lowered, and the compression ratio tailored to suit the octane rating of the fuel chosen.  While, as engine builders we always prefer race fuel for many reasons, we can modify the stock cylinder head to suit any compression ratio required.

Ignition Timing:

    The stock ignition timing curve is most often sufficient.  In some cases advancing the timing will create a stronger hit onto the pipe.  For some riders that is undesirable.  We recommend that the timing curve be altered to suit your particular style.  We like to use the Hinson billet adjustable counterbalance bearing holder, not only for the increased strength of the billet piece, but also the ability to adjust the timing advance easily.  The Hinson unit will only go to 4 degrees of advance.  The stock flywheel target pad can be altered for additional timing.  For most pump gas motors we recommend the limit of 2-3 degrees timing advance for a MX motor.  For most race gas motors would recommend a limit of 5-6 degrees timing advance for a MX motor.  Again rider preference may dictate the setting.

   Cylinder Porting Alterations:

    A MX engine is probably the most difficult to do correctly and net the desired results.  A MX engine needs smooth tractable power, as it also often requires good straight-line speed.   A fine balance must be struck between porting alterations that provide good power- but meanwhile retain good velocity for throttle response and crisp power.   The exhaust port duration is crucial in ensuring the motor is able to pull sufficient RPM, but not too high that it creates a shorter power stroke and sub peak power falls off.   The transfer port durations are altered to provide for the correct duration and area.  The intake and boost port and reshaped as well.  The transfer updrafts and the Boyesen ports are cleaned-up and modified for optimum flow.  Our MX motor set-ups pull extremely strong thru the entire spread.

Package Pricing

Package Priced at:

Note package price does not include incidental parts found faulty during tear-down and inspection.

We can build any engine combination, the package pricing is to reflect the complete package available.  Provide us with your budget and we can develop a MX package to meet your budget and satisfy your power needs!!!

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