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

I don't know if you'll get a very steady MAP reading from a V-twin so connecting the FPR to MAP may or may not be a good idea. The difference between 60kPa and 100kPa is about 6 psi which is a fuel pressure difference of around 11%, not a real lot of change, but if your MAP is all over the place so is your fuel pressure maybe - meaning the MAP is continually pulsing on a V-twin, I don't know how that would affect your fuel delivery (fuel pressure) because I haven't tried it. People have used variable orifices and plenum chambers to smooth the MAP on these motors with success, so that's an avenue too. The Buells don't reference the FPR to MAP, but at the end of the day, wire it all up and plug it all in and see what happens, then if something gives you some issues you can fix it, often the things that you think will be an issue turn out OK, but it's other unforeseen things that can cause issues, but you won't see them until you get it fired up. There's a lot of support on this forum if you have any probs.

Ian.

I have run the Buell with no Map to fuel pressure
regulator reference. I have simply run AAP reference
to the regulator to help with daily fueling offset.
Seemed to work well. All I did for fuel tuning was
run the bike on the dyno and map for varying throttle
positions vs. rpm. One I had a rough map I adjusted
my rpm bins to match the changes in the torque curve.
The Buell became a daily driver and never failed or
let me down on the road.

I haven’t been to the forum here for a while so I may
be a little out of touch w/ what set up you are using.
The system ran so well on the Ver. 1 MS that it
hasn’t been worth it to tune with later versions. In
fact, I actually went back to Ver 1 after trying a
later offshoot (I think the problem there was MS XP
not working well with the GUI to EPROM).

I have a V-Star that will most likely be fitted with
an MS-II in the future. Perhaps we can share info at
that point.

Good luck


--- FIntruder <beebispem@yahoo.com> wrote:

I'm glad to hear you think these may be in the
ballpark as far as size. How low can I run the fuel
pressure without effecting atomization? At idle
with strong vacuum pulling on the FPR diaphragm,
what does the fuel pressure drop to usually? I have
a Mallory 4309 FPR. I ASSume I am supposed to
connect a hose from the manifold to the fitting on
the regulator so fuel pressure will drop with high
vacuum like at idle or cruise.

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When adjusting the carbs on my bike with carb sticks / mercury sticks, I have to use small restrictors in the hoses to keep the mercury from bouncing and giving a hard to read level. Would the restrictors work in the hose from the manifold to the MAP sensor? It may slow what the sensor sees but should provide a more uniform vacuum reading.
How about a small tank inline that would provide more volume and thusly slow and smooth out the pulses?
Maybe both used togeather.