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Ditching your two strokes carb for Port Fuel Injection

by Charles Owens on 09/08/2011

What happens when a GM Field Engineer with a passion for High Performance Two Strokes wants more power? You got it; he develops his own Port Fuel Injection System.

Over the past few years, Richard Bruckner from High Gain Tuning has been sharing his vast knowledge of Direct & Port Fuel Injection systems with his two stroke fan base. Richard is an expert in the field having worked as an engineer for General Motors. His expertise in fuel injection, over 31 years worth has gathered the attention of many two stroke Powersports enthusiasts. When it comes to engine management, fuel injection is his passion.

Richards other passion is in designing, building and tuning High Performance two stroke engines with fuel injection. Word of Richards personal builds have spread through the two stroke community worldwide with request for a system the average tuner could install.


After speaking with two stroke engine builders, tuners and racers it became obvious it was time for a system with self intelligence as fuel injection was not at the top of anyone’s knowledge base. With that set as a personal priority, High Gain Tuning has developed an easy to install plug and play fuel injection system programmed exclusively for two-strokes. The HGT fuel injection system only needs your input of the engine’s cc size to get started. The available systems ship with the OS pre-calibrated knowing all of the perimeters needed to fire right up.


This is not a one size fits all box overloaded with drivers requiring dozens if not hundreds of hours of set-up time with little to no hope of ever running at all little lone correctly.


Richard worked with the Orbital / Synerject DiTech system for the last 4 years. “Unfortunately, there are no performance advantages” but quite a few disadvantages. Orbital / Synerject will not allow their system to be modified (once produced) for off road performance. “I have contacted them both and no sum of money would convince them otherwise.”


Direct injection is designed for ultra low emissions and moderate power, not for the performance industry. They are very finicky and costly to service. The biggest issue the air assisted DiTech’s have is the natural formulation of a non combustible emulsion of condensed water with two stroke oil vapor much like what is drained out the bottom of an air compressor tank.


 This flows through the air assist system and is injected with the fuel which causes a misfire. Even though Aprilia is aware of the issue and has even gone as far as producing a drain kit for the emulsion, most Aprilia Dealers just refer their clients to High Gain Tuning for service. “We can easily fix any Ditech issue, but they still are what they are, ultra low emission moderate performance engines. For performance, (Direct Injection) is not the answer.”


With the High Gain Tuning Port Fuel Injection System you can have your cake and eat it too.


High Gain Tuning’s Port Fuel Injection system can be installed on a ground up two stroke build or as a replacement for a carbureted application resulting in better performance and lower emissions. Some of the performance advantages of the HGT fuel injection system vs. Carbureted two stroke engines include;


1. Better performance though accurate fuel management and atomization, nearly 10% more peak horsepower as measured on the dyno.

2. Increased bottom end torque, due to fuel being injected on demand rather than needing air speed to draw it into the engine.

3. Larger throttles bodies, intake manifolds and reed blocks can be used to increase air flow since the diameter does not affect fuel flow or atomization.

4. HGT fuel Injection systems contain 192 load based fuel trimming cells vs. 3 carbureted circuits, providing instant throttle response at any rpm or load.

5. Load based ignition timing instead of fixed or linear.

6. HGT PFI engines can literally run upside down with no variation in power or fuel mixture due to vibration or g-forces.

7. Immediate restart if laid down or flipped. No way to flood the engine even when transporting.

8. Nothing to disassemble or remove to change fuel calibrations. All changes can be performed via RS232 cable or optional wireless module.

9. Different calibrations will rarely be required, as compared to carburetor jet changes, because the HGT PFI system utilizes a coolant sensor, air intake sensor and barometric pressure sensor, so fuel trim self adjusts for changing barometric and ambient conditions including under racing conditions. For example this system is extremely beneficial in the Pikes Peak Hill Climb competition because the fuel trim is re-calibrated for changing altitude and temperature conditions.

10. Easy starting at any temperature. No manual choking required.

11. Lubrication can be accomplished via pre-mix, mechanical injection or ECU controlled solenoid injection.

12. Optional wireless interface allows all data to be recorded trackside for live viewing or later playback.

13. Optional O2 sensor can be installed and data logged to facilitate tuning then removed for open loop operation.


Some of the Emissions Based advantages of the HGT FI system include;


1. Closed fuel system, no open evaporative venting or dangerous vapors.

2. Better fuel economy through better atomization

3. Lower emission through better fuel and ignition management

4. Closed loop and catalyst systems are available

5. Less fuel is consumed during deceleration via decell fuel enleanment and decell fuel cut-off calibrations if an external oil pump is used.

6. Self diagnostics with included MIL (Malfunction Indicator Lamp)


  The heart of the system (ECU) uses the latest Freescale 16 bit microprocessor, S12P, which combines High Performance with low cost including Freescale’s latest small-engine ASIC MC33812, a highly integrated all-in-one chip, including fuel injection driver, ignition driver, voltage regulator, etc.


The ECU offerings are compact in size and easy to install supporting two-stroke displacements from 40cc to 400cc per cylinder. Current production supports twins up to 800cc. Triples and custom four cylinder engines can easily be accommodated with additional drivers. The HGT PFI System can support engines spinning up to 16,000 rpm via a staged dual injection strategy.


To make changes as easy as a mouse click, HGT has developed their own proprietary self tuning software (HGT CAL) for full engine control capabilities, including communications, diagnostics, calibrations and much more at no additional cost.


What does it take to make entire calibration and “jetting” changes using the HGT PFI system? Watch this video for the answer.

Richard and the folks at HGT will develop a PFI system for any two stroke. Systems already developed and Dyno tuned can be purchased and installed outside of HGT with little effort. To do an engine in house HGT

rarely needs more than the engine and pipe.


Please contact them for additional information.


A huge thanks to John Nicholas and Richard Bruckner from HGT for the work on this article.