Crazy idea...

[Toehead]

Jury is still out on performance. I've only had the one ride. It didn't seem down all that much on power, but it certainly wasn't an enhancement.

I've got a lot of tweaking and tuning to do before I know where it sits vs. the stock carbs. My stock carbs were just given a Randakk kit, so I have a good baseline.

The throttle body I have, IIRC, is 40 mm.

[DaveyG]

Hmmm... Well once you get the ms fixed and tweak it a bit more I'll definitely be curious on your butt dyno results.

[Toehead]

I used the calculator here when sizing the throttle body: http://www.hipermath.com/engines/throttle_body_size

it gave me 35 mm required for "street", 40 for "high-performance".
I'm not sure how valid this is....

[DaveyG]

Interesting... Crazy how the modern midsize sport bikes use such huge tbs... Even like 600s now using 4 36mm ITB setup.

[KYpondman]

Power @ very high RPM (IMHO). I hear those bikes going by my place and they are just screaming.
Claude

[Toehead]

Power @ very high RPM (IMHO). I hear those bikes going by my place and they are just screaming.
Claude

This makes sense, as required air is a function of both displacement and RPM. If they make their peak HP somewhere around 12k - 14k rpm, that means a much bigger throttle body...

[robin1731]

Big difference in how the heads flow too.

[DaveyG]

OH yeah I'm definitely not comparing our old GL engines directly to new 600s, just find it interesting how old ~90hp engines run pretty good with such minimal airflow, compared to modern ~120hp engines seem to need 3x as much throttle area.

[robin1731]

Partly because those 600's do make closer to the 120 or more HP listed. But the GL's probably didn't make the 82 listed by Honda in 76. They all played games with the numbers back then.

[thewingsof81]

If you're going for cheap and easy, rebuild the carbs and ride your bike.

If you're not using the stock coils and ignition system then you need a way to get a tach signal (trigger wheel, vr sensor). Also need a fuel pump, filter, lines, coolant temp sensor, air intake temp sensor, fuel pressure regulator, etc.

Here is some good info on the microsquirt http://www.msextra.com/doc/pdf/html/Mic ... e-3.4.html

It is not impossible, but also not a small project.

Now does this act as an ecu in some way to add up to date computerized parts.

[Toehead]

Yes, it is a somewhat open-source fuel injection computer. It brings all the functionality of modern EFI.

[Gator417]

Just curious about something. Since you got all of those good bits from the cbr, why not go all the way & get the ecu as well? I know its not pnp, but it seems like it would be less expensive to get a Power Commander or equivalent than a MS system.
Also, motorcycles require bigger TBs because each TB feeds the corresponding cylinder. With an auto (typically) the TB feeds the intake plenum & each cylinder pulls from there, but only one at a time. Very interested in seeing what you end up with.
Gator

[DaveyG]

Gator, that would require a ton of extra work, you'd also need the CBR ignition and myriad sensors to get the ecu to even trigger. Modding the GL to accept ALL of the CBR parts would be significantly more work than the few parts you'd need to fabricate for the MS ecu. This project is sidelined currently at the moment, just too much business work drowning me currently to play with it.

[Gator417]

Those bikes have COP ignition, so that would save a lot of hassle. Plus I think it would be much better to have the ecu control both fuel & ignition curves. The rest of the sensors have to be added or modified for the MS to work anyway. I don't see how it would be any more work than starting from scratch, making your own harness, fabricating brackets and finding the right sensors etc. Do they have a bunch of extra sensors? My F4i had a pretty simple looking harness with only a few input sensors. My biggest concern would be getting all of the fuel and spark timing converted correctly.
Gator