MicroSquirt.com read only forum (Jan.15,2018)

I'm new to the site but I've been looking round on the forum to get some answers to this question myself having just purchased a uSquirt ECU.

There is another similar thread already started, but my initial answer was turning out to be a full on thread hijack, so I've started my own - I'll link the 2 threads so information can be shared. http://www.microsquirt.com/viewtopic.ph ... 72#p150672

If anyone spots any errors then please correct me or point in the right direction.

I am uSquirting a small cc bike engine, originally a 125cc, now 140cc with a few other mods.

What I have ordered so far is:

The uSquirt ECU & suitable trigger wheel and CPS
Throttle body from an 09 Honda CBF125, which seems to have a TPS, Injector and possibly a MAP or AIT sensor (looked very similar to a CBR125, but cheaper - probably the same part)

Fuel pump from a an 09 Honda CBF125 - externally mounted with 3 hose connections, presumably supply/return from tank and fuel 'rail' supply

2 x GM 1 bar MAP sensors - very cheap, I may be going forced induction at some point, will only be running 0.5 bar boost so should be OK and I ordered 2 so I could run Barometric compensation.


I'm hoping to use the stock flywheel pickup coil to act a CPS, but have bought a suitable uSquirt CPS just to be on the safe side as the stock setup has one pulse per revolution so may not have the resolution needed for a 36 tooth trigger wheel when the revs get up, it currently pulls 12.5krpm so this may be an issue.

I'll be mounting the trigger wheel on the stock flywheel, which will involve removing the rivets that hold the flywheel together and remounting using bolts/loctite - the original pulse trigger will be removed from the outer of the flywheel in the lathe so as to not give potential false pulses.

There are a few ignition coils in the workshop that can potentially work with this setup, failing that a VW/Audi coil will be used, they have single HT output and are physically small so hopefully ideal.

Luckily I have a few spare engines of the same type, so I'll be able to iron out the pyshical installation bugs I'll no doubt stumble upon before fitting it to the intended recipient bike.

Any pointers would be much appreciated.

monstermonkey wrote: Any pointers would be much appreciated.

You've got enough bits there to get you started, but the first thing I'd do is make a rig to rotate your crank wheel and hook that up to a coil. A cheap variable speed router or cordless drill is ideal, for just checking the basics out. It's a lot easier to get to grips with stuff that way. Once you have the basics working, transfer it to an engine.

Sorry for the slow reply, I don't have reply notifications setup.

I pretty much jumped in and mounted the trigger wheel to the starter clutch/flywheel mount by removing the rivets that hold it all together and drilling the trigger wheel to suit, I mounted the CPS through the engine case instead of modding the existing one.

I opened up the combined TPS/AIT/MAP sensor on the throttle body and found which wires do what, I've calibrated the TPS and fudged the AIT & MAP sensor to give right-ish readings.

Following a big face-palm moment I realised I didn't really need 4 sparks per revolution so have changed it to 1 per rev, it's a runner as can be seen here: http://www.youtube.com/watch?v=aeJu_bKnsV4

I've got plenty or work still to do, I'm going to check the original ignition map with a strobe and use that as a base point, I've bought a 2J1 wideband setup and need to get an injector with known parameters so I can set the fuelling up a little closer to what's needed.

The fuel pump is mounted up, but not ideally, but it seems to use a very small amount of current, a quick measure showed 0.5amp, I need to check this more thoroughly with a different meter (I used a cheap one)