Off Road motorcycle Fuel Injection 101

Eddie Sisneros

The intent of this article is to give a general over view of current off road motorcycle fuel injection. There are alot of myths and misunderstand regarding fuel injection in this realm of usage.

Lets start with what fuel injection can and cannot do as far self compensation. It cannot compensate for any change in flow. Regardless of intake/exhaust changes,fuel type or engine mods the ECU will contiuinue control the fuel and ignition as if it were stock. There is no sensor that monitors flow. What it can do is compensate for elevation (barometric pressure sensor) and air temperature (intake air temperature sensor). If the base fuel and ignition map are correct and the bike runs perfect in one condition,it will also run perfectly as the conditions change.

The reality of the situation is just like stock carburetor jetting isnt perfect neither is the stock fuel injection mapping. Until the manufactures update the systems to use oxygen sensors and/or air flow meters it will be up to the end user the correct the fueling and ignition for the specific modifications done and conditions/situations they are used in. Fueling is corrected for flow changes. Ignition timing is altered to tailor the power delivery and to take advantage of low grade or high grade fuel.

So how do you go about tuning your fuel injected motorcycle? You first need to purchase/aquire the fuel injection tuning device you desire or use the services of a tuning specialist such as my self or several others. If you intend to do your own tuning you will also need to invest in a wide band air fuel ratio meter. With out a wide band air fuel ratio meter you will be just guessing and may as well be blindly pounding on the key board.

Once you have the fueling correct you can move on to altering ignition timing to change the power delivery. You must have a device capable of altering the ignition. Currently only the OEM flash tuner offer this option. All other "piggy back" tuners are not currently capable of controlling the ignition. The "piggy back" tuners do however offer much more friendly and quicker to use. The ultimate way to tune is via the use of the OEM flash tool to control the ignition and "piggy back" tuner to control the fuel. This may be cost prohibitive for most end user unless you enlist the service of a specialist. In that case you don't actually buy the OEM flash tuner.

If you are lucky enough to live near or able to travel a to a capable tuning specialist they can tune your motorcycle on a dyno. This is the most accurate method. However a reflash via mail or purchasing a tuning device with a

pre loaded map for your specific set up can work very well.

In the next installment i will cover the capabilities of the different tuning devices on the market and pro's and con's of each.

Eddie Sisneros

User Feedback

There are no comments to display.

This is now closed for further comments

  • Similar Content

    • By Serg Orlovskiy
      So i never owned a fuel injected dirt bike, I got a 2016 yz450f for a steal at an auction. It ran great every kick since this last ride, it started dying when i wasn't on the throttle. 
       I got it home and now the second i put the choke in it dies/ it runs/rides when im on throttle but if im not on the pipe it dies.
      I went check the valves all in spec, found a video how to flush fuel injector with a battery, flushed it still doesn't idle with choke in.
      Now im clueless what to do usually a problem like this I clean out the carb and that fixes the problem (get a fuel injected bike they say...) ha, I only run non ethanol fuel through all my machines. so what are my next steps?
      and is the upgraded ecu with the tuner worth the $?
      any specific tips/things to do to make sure thing runs like a top every time/ things to know when Im out in the field to trouble shoot a injector?
    • By trouble_maker
      Ok fella's here's the story. Bought a 2018 250 XCW TPI in December of 2017 had for 2 weeks and had 3 hours on it, took it back to the dealer with a hard start, no start problem. They had it for a week and couldn't find any problems, even though I had video of the problem. Then they charged me $150 because they couldn't find anything wrong with it. So KTM warranty ain't worth a crap. This problem is now intermittent and getting more frequent. The bike has now produced a new problem. (25 hours) The bike now never gets on the pipe/power band and feels as to be loading up, never cleans out. Called KTM again and all they say is take it to the dealer, yeah right! LOL Over the past two nights I've completely torn the bike apart, EVERYTHING! (just shy of splitting the cases) I have checked and confirmed every sensor, plug, wire, spark plug,connector, timing, crankshaft key, reeds, Air filter, powervalve, fuel pressure, ground, power, battery, piston, rings, filter, injectors, fuel, oil pump, etc..... 
           Has anyone had any of these problems with their TPI? If there is anyone from KTM on here please contact me. 
    • By mebgardner
      This "plug and play" kit has been developed so that the very fine Golan Mini Filter, 10 micron, can be fitted in-line to the KTM 690 Enduro & SMC motors, between the fuel tank and the injector, but can be easily accessed for cleaning and servicing without having to remove the airbox.
      It consist of a custom-built length of high-pressure OEM fuel hose, and OEM quick-release couplings and a Golan Mini Filter.This can be easily attached by disconnecting the OEM dry break and fitting our filter kit in between, and only requires the removal of the airbox once for fitting this kit.
      We have found the 10 micron Golan Mini Filter, which can be unscrewed and the filter washed, virtually removes any problem with injectors blocking, which can be a pain on long trips.
      Will work with or without our EVO1 & EVO2 tanks fitted.
      Suits all KTM 690 Enduro & SMC
    • By mebgardner
      Made in the USA !
      CJD-FFNK-690 Kit shown in all three colors =  KTM LC4 690 Enduro/SMC 08′-17′ ( Product show in picture is current ).
      The separate diamond shaped billet aluminum cover plate is now ALL ONE PIECE for aesthetics giving that OEM appearance on the 690.
      The stock KTM LC4 690/KTM 990 SMT fuel fill suffers from a few problems. The stock key lock system is susceptible to breaking keys, it also has a reputation for allowing dirt and grime in which is a huge problem on EFI systems and lastly the flip up cap can be cumbersome for filling with fuel or getting to your luggage. Our answer is a billet fuel neck that attaches directly to your gas tank, using the stock o-ring for a nice fit. Venting is done at the same 90 degree angle as OEM which eliminates having to use a breather vent cap. If you have removed the SAS system you can cap the body vent and vent from the top with a breather listed below.
      The fuel fill is CNC machined from ONE piece using aircraft aluminum, not a 2 piece welded part like others, and hard anodized. Specially crafted to replace your OEM system. No modifications to your bike or tank are necessary – simply remove the original and bolt ours into place.  Includes an Acerbis Viton sealed plastic fuel cap, which can easily replaced if need be. All hardware and mounting instructions included. Lightest kit on the market.
      Also works on your KTM 990 SMT with this style filler system.
    • By Duneman97
      Hello everyone. I looked around and I couldn’t find anyone that had my problem so I was hoping someone here could help me out.
      I recently bought a 2017 wr 450 with higher hours but it was well setup with a timbersled kit, Heated bars, thermobob, handguards. Stuff like that. I test rode it with the timbersled kit and it ran great at the 8500’ elevation.
      Now that I’ve had it around the yard, and in the lower elevation mountains where we live I’ve noticed a serious bog when matching throttle on deceleration, and at low-mid throttle when revving in neutral. But the bike will rev through it if you open the throttle more. There is also a fair amount of soot on the exhaust.
      Bike has uncorked oem exhaust, K and n filter, Fresh plug. The next step I’m at would be to get the tuner and comp ecu, as well as putting a regular air filter system.
      Any help will be greatly appreciated