Thread: Tricking the EMM? MSX140
02-25-2009, 10:38 AM #1
Tricking the EMM? MSX140
I've been thinking about how to "rejet" a FICHT motor. Normal tricks on fuel injected bikes won't work due to how the FICHT injectors work. So I was thinking about how to fool the emm into thinking the air was more dense.
Apparently for every 5 degrees Farenheit temp drop, air becomes 1% more dense. a 4% increase in density could be achieved by making the computer think it was 65F instead of 85F, as an example.
I needed to change my air temp sensor due to the lovely design of the F/A on the 03 and early 04 MSX140's. So, I brought the F/A baseplate inside from the garage, shot it with my Raytek and took resistance readings every 5F. At 65F the resistance is 936 ohms. At 85F the resistance is 1040 ohms. I did every temp from 45 to 85 just to ensure it's linear. It's not, but close enough.
Hooking resistors in parallel will create lower resistance. formula is R = (R1 × R2) / (R1 + R2)
Long story short, if I hook a 9300ohm resistor in parallel with my Air Temp Sensor, it should trick the emm into thinking air is 4% more dense, and add 4% more fuel.
Am I thinking clearly? Any flaws with this?
02-25-2009, 11:06 AM #2
That sounds logical. Perhaps you could use a variable resistor in series to adjust on the fly? With no other changes to what you have now, it should be easy to see how the fuel amount changes with the wash pattern eh?
02-25-2009, 11:19 AM #3
Unfortunately no. If I'm understanding correctly, FICHT motors don't develop the wash patterns like normal 2 strokes, as the fuel doesn't come in thru transfer ports, it's injected from the center of the head. Dunno really, I've only owned the ski a month, and haven't ridden it yet.
If what I've read about lack of normal wash patterns is correct, it makes it a PITA, eh? I was talking with Randy about monitoring EGT's, but he didn't seem to think it was worth it.
02-25-2009, 12:13 PM #4
- Join Date
- Jul 2007
- Cedar Rapids,Iowa
k447 is going to be one of the best Sounding board,Bernie also should have some input of ideas. How are you figuring on increasing better air flow?
02-25-2009, 12:19 PM #5
02-25-2009, 12:23 PM #6
What type of fuel regulator does the FITCH use??
02-25-2009, 12:35 PM #7
Unfortunately, the FICHT injectors don't work that way, they're a solenoid. Raising pressure only fills the idle injector more quickly; it won't affect the quantity sprayed in.
02-25-2009, 12:37 PM #8
and whats the benefit???burning more fuel will cause it to be rich and hurt hp unless its so close to the edge right now its on the lean side as is.or are you considering bigger throttle bodies or triples???either way i believe the real issue was that the fi bodies simple can't supply enough fuel for either upgrade
02-25-2009, 12:45 PM #9
I'll take that 10%, if I can!
I'd love a set of triples! Send them to me, I'll powdercoat them and give them a nice home! The reason I'm looking into this is I simply can't get a set of triples, or pretty much anything else performance-wise for this ski. That, and I don't like being told something "can't" be done.....
02-27-2009, 06:36 PM #10
- Join Date
- Jul 2007
- near Toronto, Canada
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