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greg737 · June 22nd, 2011, 04:23 PM

I'm still using the bike's original petcock. I just took it apart and modified it so that it no longer needs engine vacuum to flow, so it acts as a simple on-off-reserve petcock. And I capped off the petcock's vacuum line.

On the throttlebody I added a fourth vacuum nipple, drilled into the same position as the other three that it originally came with.

I'm using two of the vacuum nipples, one from each of the two cylinders, for vacuum input to the MAP sensor (Motorola MPX4250A). The EX-250 produces a very "lumpy" vacuum signal so I've got restrictors in these two lines and I'm using a small fuel filter (lawnmower type) plumbed in-line after the restrictors to smooth the signal into something that's useful to the MicroSquirt.

The other two throttlebody vacuum nipples (one on each cylinder) are actually not acting as vacuum inputs. Instead they're hooked up to my cold-startup "fast idle" air circuit (it's an "automatic choke").

I'm using a Nissan Altima EGR solenoid ($5 at the you-pull junkyard) that opens based on the engine water temperature sensor. Below a certain engine water temperature the Microsquirt commands extra fuel through the injectors along with the extra air that is ported through the ex-Altima EGR soleniod from a connection plumbed into the K&N 0990 air filter to the two vacuum nipples (bypassing the butterflys).

Once the engine's water temperature reaches a pre-determined value the solenoid closes and the fueling level returns to normal.

I've even got an amber LED light on a small auxilliary indicator panel I built that comes on when this logic is engaged. It's also got other lights that indicate the following: Injectors firing, O2 sensor is at operating temp, warm up enrichment, acceleration enrichment and fuel pump operation.

June 22nd, 2011, 04:23 PM	#75
greg737 - Name: - Location: - Join Date: May 2009 Motorcycle(s): - Posts: A lot.	I'm still using the bike's original petcock. I just took it apart and modified it so that it no longer needs engine vacuum to flow, so it acts as a simple on-off-reserve petcock. And I capped off the petcock's vacuum line. On the throttlebody I added a fourth vacuum nipple, drilled into the same position as the other three that it originally came with. I'm using two of the vacuum nipples, one from each of the two cylinders, for vacuum input to the MAP sensor (Motorola MPX4250A). The EX-250 produces a very "lumpy" vacuum signal so I've got restrictors in these two lines and I'm using a small fuel filter (lawnmower type) plumbed in-line after the restrictors to smooth the signal into something that's useful to the MicroSquirt. The other two throttlebody vacuum nipples (one on each cylinder) are actually not acting as vacuum inputs. Instead they're hooked up to my cold-startup "fast idle" air circuit (it's an "automatic choke"). I'm using a Nissan Altima EGR solenoid ($5 at the you-pull junkyard) that opens based on the engine water temperature sensor. Below a certain engine water temperature the Microsquirt commands extra fuel through the injectors along with the extra air that is ported through the ex-Altima EGR soleniod from a connection plumbed into the K&N 0990 air filter to the two vacuum nipples (bypassing the butterflys). Once the engine's water temperature reaches a pre-determined value the solenoid closes and the fueling level returns to normal. I've even got an amber LED light on a small auxilliary indicator panel I built that comes on when this logic is engaged. It's also got other lights that indicate the following: Injectors firing, O2 sensor is at operating temp, warm up enrichment, acceleration enrichment and fuel pump operation.