There is a NTC temperature probe (the middle cable) that you run to somewhere on the bike exposed to the outside temperature so it's not affected by heat soak like the OEM could possibly be.
I tested the probe with my multimeter and it reacted to the warmth of my hand pretty quickly, so I think the principle is actually sound. It's simply the price I take exception to.
What resistor did you use out of interest - I couldn't help ruining the resistor as I cut the potting off and need to work out the colour bands.
Ah okay I missed the NTC wires. Makes more sense now.
My messages about the resistor are in the forum messages somewhere here, but off the top of my head it might have been around 20-30k, and I was going to bridge it with an NTC but didn't bother once I realised that the difference in fueling for a 15 or 20 degree range of temperature that i use the bike for, was small.
Any resistor over about 10k will start to enrichen the mixture
I note on Boosterplug's website this statement of a 'problem'
"The problem using a serial resistor is that the amount of added mixture will vary a lot with changes in ambient temperature, and this is certainly not what we want."
I agree, a constant level or enrichment is a better idea, but at no time is a simple resistor ever 'bad' or dangerous, it's just not quite as refined that's all, and the engine smoothness will remain the same (pretty much) in both cases.
I felt a better respose, which made the bike feel more lively, was to advance the ignition timing about 4 degrees. This was a common mod on early carb bikes, which takes into account that bikes imported to the UK are set up for lower 92RON fuel, but the lowest quality we can buy is the better 95RON. As fuel quality goes down ignition timing has to be more retarded, so as we don't get less than 95RON and can get 99RON a 4 degree advance is pretty safe. I went about that by 'dremelling' out the mounting holes of the flywheel pickup sensor into slots a couple of mm long.
And then finally i went for a remap from Samios. There is no more ultimate power from the remap, but two benefits I felt made it worth it was the removal of any torque limiting in lower gears, which on 850's is achieved with the gear selector switch, on 900's it's hardcoded into the ECU. Easy to fix on an 850, but reprogramming is needed for the 900.
The best part of the remap for me though was the removal of fuel cutting when decelerating. Fuel cutting saves a bit of fuel when you're slowing down, which wasn't possible with carbs. When carbs still meter out a small amount of fuel on deceleration you get a smooth transition between on and off throttle positions. With the remapped ECU it makes it possible to keep the throttle gently active around roundabouts and so on. I previously felt the throttle was 'choppy' when trying to gently control speed at low revs. After the remap, the throttle became smooth instead and it feels almost like riding a a bike with carbs.
I do use more fuel but I don't think it's even noticeable and definitely not noticeable when I'm riding in a style where I'm 'making progress'.
I spent a bit of time trying to work out what a retrofit device would need to do in order to emulate the anti fuel cutting on a standard bike. I've got a few ideas. I think it could be done just by using 4 wires and a control box. I haven't made a prototype but maybe I should have a go at it, I've hooked up an oscilloscope so have plenty of data, it's just a matter of reliably emulating a fuel injector firing signal after the ECU has cut it, and the timing of it doesn't need to be accurate to even 5 degrees of engine rotation so it's probably something which could be done.
If I made one it would probably work for most other injected bikes, and I could make and sell a £130 'box of tricks' too !
Edited by fixitsan, 21 December 2023 - 08:38 am.