250cc and 270cc billet 2-Stroke Engines for UAS and RWYB Kart Racing

This picture shows the first Vindicator with the standard PVL ignition. This ignition is cost effective, reliable, and offers very good performance.	This Vindicator is equipped with the optional Zeeltronics programmable ignition. We had just started experimemting with this ignition but are very pleased with the results of our early testing.	The basic Vindicator engine package comes with all of the items shown in this illustration. The 45/42mm Tillotson HM-1 carburetor is converted to methanol. Not shown is the electric fuel pump that is activated when the throttle pedal reaches the 1/2 open position. This provides crisp operation off of the corners but all the fuel needed at full throttle. This concept was pioneered at Bergfelt Racing Enterprises, LLC.
The Vindicator was designed to be used with an electric water pump. One package option combines the entire cooling system with the engine. This makes it simple to switch from one engine type to another with minimal work. The Bosch water pump that we use has proven to be durable and reliable and is one of the most popular water pumps in UAS kart racing.	The tuned exhaust pipe was designed just for the Vindicator by Greg Sims at Sims Power Chambers in Australia. Because the shipping from Australia is so expensive we make the standard pipes in-house at Bergfelt Racing Enterprises, LLC using the design provided by Greg. Although this pipe looks just like any other 2-cycle tuned exhaust, there are a bunch of special features hidden inside that broaden the power band of the engine equipped with this pipe.	We want our customers to succeed and not have to experience unnecessary problems and expenses. To that end we have produced an Owner's Manuel that comes with each engine. The Vindicator is under constant development so we will update the Manual on a regular basis. All a Vindicator owner needs to do to find out about the latest developments is to ask.
Our crankshaft extension/driver hub is made from tool steel. It is made to accept a 40mm driver pulleymade by Hegar. That pulley is a wear item that is easy to get and replace. Although Bergfelt Racing Enterprises, LLC does not supply them, we recommend using a jackshaft assembly made by BMI. These units are relatively inexpensive and work well with our engine. We also recommend using a Birky clutch set to come in at 8000 rpm. The clutch will need a 50 tooth pulley.	The Vindicator exhaust header is made from billet steel and has sealing o-rings.	The Vindicator owner will need to install three switches on their kart. One controls the water pump, another the fuel pump and the third the ignition. Another required item is a 12 volt battery that is designed specifically for motorsport applications. Batteries designed for lawn and garden use simply will not last more than a few laps.

The Vindicator was designed primarily for open class speedway kart racing.  It is a billet crankcase, reed valve induction, liquid cooled high performance engine.  The cylinder, crankshaft, connecting rod piston and cylinder are the same one used on KTM moto-cross motorcycles produced from 2007 to 2016..

We have been asked why the late model KTM design was chosen for cylinder and crankshaft to be used in our Vindicator crankcase.  That answer is simple.  The KTM makes the most peak horsepower.   On an open class speedway kart the engines’ job is to make as much horsepower as possible over an rpm range of 3,000 to 4,000 rpm.  At Bergfelt Racing Enterprises, LLC, we believe the KTM cylinder and crankshaft to be a perfect components with which to start. Early experiments with a cast type crankcase lead to the development of the billet case Vindicator.  Cast crankcases are prone to air leaks and inconsistencies in material strength from engine to engine that make reliability less predictable than with the billet case.

When designing the Vindicator the cylinder and piston were turned 180 degrees to allow the exhaust to exit from the rear.  This also makes positioning the carburetor in the front of the engine easier which is more practical for a kart application.  Positioning so that the exhaust exits at the rear allows for weight distribution that is more suitable for speedway kart racing.  With other moto based 2 strokes used on karts and other small race cars the HEAVY exhaust pipe is positioned to the right and above the engine.  This raises the center of gravity significantly and biases the weight to the right side of the kart…which is the wrong side for speedway kart racing.  The exhaust pipe for the Vindicator, designed by Greg Sims form Australia, sits low in the kart.  The heaviest portion of those pipes is the specially designed exhaust exit end, designed specifically for the broader power band required of a speedway kart engine.  That heavy portion ends up being on the left side of the kart which helps with balancing the weight distribution for better overall performance.

The rpm range of operation of a speedway kart that does not shift gears is different than a motocross motorcycle that does and must traverse all types of terrain.  For that reason, Greg Sim’s designed to pipe for optimum operation in the rpm range used for speedway kart racing.

The Vindicator crankcase was designed in such a way that almost any readily available ignition system can be used.  The standard ignition chosen was the KTM version of the PLV high performance ignition.  That ignition is popular on other karting specific engines and many know how to work with and adjust it.  It is the most user-friendly ignition we know of. 

The Vindicator engine will accept slide throttle, float bowl carburetors found on motor cross motorcycles however all of our testing, so far, has been done with the Tillotson HM 1.  When Tilloston was first developing the HM1 Bergfelt Racing Enterprises, LLC was sent one to test, modified and needed and then report back our findings.  Since filing that report, we have done considerably more testing and have worked out the details to make the HM1 into an alcohol carburetor.  Since the Vindicator is primarily intended for UAS racing, the engine is set-up from the very beginning to be run on methanol (alcohol) based fuel.

With a 45mm throat and 42mm venturi the HM1 has more area to pass air than many dual carburetor set-ups found on other common UAS engine set-ups.  Using a single carburetor that can be simply adjusted for different atmospheric conditions just by turning a couple of screws makes the HM1 the most user-friendly carburetor that we have come across that also performs well. Along with the carburetor, Bergfelt Racing Enterprises, LLC invented a fuel system that uses an electric fuel pump that is activated by the throttle control rod. At idle and low speed the pump is turned off for clean idling and crisp performance off of corners. The pump is turned on at half to full throttle to provide all of the fuel needed to make full power.

Although the HM1 provides great performance, by itself it’s fuel pump cannot supply enough fuel at full throttle operation of a 250cc two-stroke engine.  By altering the inlet needle pop off pressure and adding the electric fuel pump and check valve to the fuel pump, we have been able to achieve results that mimic a throttle body fuel injector. 

Most race kart engines are sold without any type of owner’s manual.  This has caused many racers to make many unnecessary, avoidable and costly mistakes and lost performance.  We have decided to put into writing what we have learned from testing proto-types to help those who have chosen the Vindicator as their engine to avoid the miss-steps we have already experienced.  However, please be warned; the Vindicator is still relatively new to the open class speedway world and it is under constant study and development.  Vindicator users are encouraged to contact Bergfelt Racing Enterprises, LLC from time to time to check on new developments.

Late in 2017 Bergfelt Racing Enterprises, LLC consulted with Wiseco Piston to design a propriarity piston to combine with a stroker crankshaft that will allow us to built a 270cc version of the Vindicator. The 270cc version option is available at additional cost.

All Vindicator engines are custom built to order.

Please email or call Bergfelt Racing Enterprises, LLC to get a price quote for your Vindicator engine.

Contact Mark Bergfelt; email; mark@bergfeltracing.com or call 724-462-7440 or send a message on Facebook.