Your Fuel Injected Bike - You’ve added a fancy exhaust now what?

Typical stock bikes have fuel curves that are far from optimal for ride-ability and performance. Usually they are a compromised because the bike from the factory maybe set up for economy or because the bike has to pass stringent emissions tests. For example Ducatis in the US are sometimes geared high with an extra tooth on the rear sprocket to pass noise tests. This same logic is used for the fuel system and all bikes are usually set up much leaner than they should be in order to pass.

It is difficult to quote exact figures but some have suggested that factory bikes are only 70% optimum and maybe even as low as 65% after fitting aftermarket exhausts as the bike tends to a leaner fuel mixture when the restriction of a factory exhaust is removed. To get back the performance built into the bike the mixture needs to be enriched slightly back to the ideal fuel /air ratio for optimal performance. Chemically the ideal stoichiometric ratio is 14.7 but for performance 12.9 to 13.2 maybe better. On a carburetored bike the usual fix was to increase the jet sizes but how to do that on a fuel injected bike. For explanation of fuel injection see Fuel-Injection, How Does It Work

One answer is to install an electronic jet kit. This is a plug-in auxiliary electronics unit that goes between the bike’s factory ECU and the fuel injectors. What it does is to receive the injector pulse from the ECU and extend it slightly to increase the amount of fuel the stock injector delivers
One such unit is the Electronic Jet Kit © from Techlusion / Dobeck Performance one of the pioneers in this field. It comes, bike specific, preset from the factory but the rider may adjust the settings himself by simply pressing buttons to change the fuel air mix, just like he would have done in the good old days by changing jets. . Unlike the early “black boxes” which provided false sensor inputs to fool the ECU, the EJK does not interfere with the bike’s OEM system; the bike can still make the necessary adjustments for temperature or altitude. Also because EJK does not interfere with the bike’s OEM operation, the changes it makes are load based so fuel consumption does not suffer drastically and fuel is only added when needed. Some bikes use Gen3.5 which can be connected to a PC.

Many fuel injected bikes, available or even manufactured in Thailand, can benefit from the fitting of an EJK. Such as Kawasaki ER6, Versys and KLX250, Honda’s new CBR250, All Ducati’s, Triumph, Harleys and even the humble Honda PCX scooter. Application list can be found here

Harley owners may look at ´TFI Questions Answered' for information on Harley GEN 3.5 applications and settings.

As 100% benzene/petrol or gasoline is phased out in Thailand an additional benefit available after fitting an EJK is the ability to add fuel to compensate for the little extra needed when running on E10 or E20. This allows older Fuel-Injection bikes to perform optimally on gasohol without replacing the factory installed injectors.

For more information, you can contact the Thai distributor by email: ejkthailand<at> (Thai or English)
  • Currently 2.00/5
Rating: 2.00/5 (3 votes cast)

Share It!


Monday, 28 February 2011 @ 10:24 PM ICT
We moved this comment to our forum, you can find it here Upgrading a Carburetor Motorcycle to a Electronic Fuel-Injection Bike
Edited on Wednesday, 02 March 2011 @ 10:01 PM ICT by admin

Anonymous User

Thursday, 19 May 2011 @ 12:34 PM ICT
Dobeck Performance just released their EJK for Honda PCX. Early results give about 1hp increase on standard bike along with an increase in torque.

No info yet on bike with after market exhaust.

See Honda PCX - Another performance upgrade product for more information...
Edited on Thursday, 19 May 2011 @ 01:17 PM ICT by admin