400cc Stroker Gas Engine:

    Do you have a real need for speed?  Do you like to be top dog among your buddies?  Then a 400cc Stroker Gas motor is for you!!!  Equally adept at the nastiest of hillclimbs to drag racing- this motor configuration flat rocks!!!  An incredible increase over stock power- substantial torque and power curve.

Pipes:

 We highly recommend CPI in-frame drag pipes.  With the increased bore size and increased stroke the loss of low end power from the CPI in-frame drag pipes is negated.  The CPI in frame pipes also allow the motor to turn a greater RPM than most in frame pipes allow.  The aggressive design on the CPI in-frame pipes scavenge the larger bore size better creating more peak power.  Secondary choice would be Toomey T-5's.

Carbs:

  We highly recommend 35mm Keihin PWK carbs.  Independent dyno testing has shown that these carbs produce more horsepower and torque over the Mikuni carbs.  For this motor the stock air box is no longer an option.  Patriot Racing has found a perfect K&N filter set that are nice and large for good airflow, but can be set-up to clear the stinger tubes and not melt.  Secondary option would be for 28mm PWKs bored to 30mm's. 

Reed cages:

  We have tested and found the V Force cage to provide the best power throughout the power spread.      For more all-around/duner we recommend V-Force reed cages with the Pro Design V-Force compatible intakes. .  The V Force cage with its W design provides for superior intake velocity, which equates to good throttle response.   We have not seen nearly the failure rate as some people who are peddling their one piece set-ups claim to have!  Their margins are better on the one piece set-ups, so its a business based decision not a performance based decision!

Crankshaft:

  The heart of any good engine is it crankshaft.  Patriot Racing can not stress enough that a good solid crankshaft ensures many hours of trouble-free use.  We recommend a forged stroker crankshaft with a plus 4mm stroke and 115mm "long" rods.  We use Blaster pistons for this set-up.  The cases do not require any additional work to clear the crank.  A good serviceable stock crank can be stroked and fitted with rods as well.  However a new plus 4mm forged crankshaft cost is nearly that of stroking a stock crankshaft.

Cylinder head:

  An aftermarket billet head with domes for a 15:1 compression ratio on race fuel is the best performing.  We do not recommend using pump gas for this motor.  The octane isn't sufficient enough, also the constantly changing gas formulations found in pump gas do not readily mix with a high output engine such as this.  Additionally with the increase in stroke length that must be accounted for the in the head design a billet head is the ideal choice.

Ignition timing:

  At a minimum the stock stator mounting plate must be modified to provide for at least 4 degrees of timing advance.  The ability of the motor after cylinder porting alterations and the pipes fitted allow for a greater peak RPM- this higher peak does not suit the stock timing curve.  We recommend 2 degrees advance for pump gas motors and 4 degrees for race fuel motors.  With the increase in stroke the timing requirements change.  Stroker motors typically require less timing advance due to the new piston position relative to the stock ignition trigger point. 

Cylinder porting alterations:

  With our 400cc stroker engines the differing stroke, rod length, and piston configuration require some special attention to the port timing adjustment.   We work with the customer to determine their exact power delivery needs- then we apply our experience and knowledge in reworking the cylinder porting arrangement.  Initially with the increase in crankshaft stroke the port timings absolutely must be corrected for proper power output levels.  A stroker motor most often CANNOT be built using previously ported cylinders.  The transfer duration becomes too great and cannot be readily corrected.  The increase in displacement requires even more attention to the already deficient transfer ports.  We spend a considerable amount of time correcting these flaws.   The stock intake size works well up to 34mm carbs- but in our recommendation of 35mm carbs, the intake port size must be increased  by a small percentage- the intake is also reshaped for correct flow patterns.  We've tested and found an exhaust port duration that suits the CPI in-frame pipes extremely well- coupled with the correct shape and width the total sum of the the cylinder porting alterations provide for a extreme increase in peak power output.

Package Pricing

Package Priced at: $2295-2995

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 an engine package to meet your budget and satisfy your power needs!!!

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