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Here are a few measurements of how the clutch switch affects the fuel injector pulse width on the 2nd gen (fuel injected) SV650. These were taken with an oscilloscope hooked up to the signal going to fuel injector #1.

If you're thinking about bypassing the clutch switch on your 2nd gen SV, take a look.



-If you do a simple bypass, (just shorting the clutch switch), about 25% extra fuel (2.72mS vs. 2.20mS) will be added from just off idle, up to about 3,300 RPM, since the ECM thinks the clutch is always pulled in. This may affect gas mileage, and possibly driveability.

-If you do a smart bypass (where you clip the clutch signal to the ECM to make it believe the clutch is never pulled in and then bypass the switch), the bike may be harder to start, since the ECM will not know to richen the fuel or bump up RPM. Many people have done this though, and reported no problem with starting.

- Both RPM increase and pulse width widening only happen from about 1,500 to 3,300 RPM. Over about 3,300 RPM, the lengthened injector pulse width abruptly changes back normal width.

-When the bike is in neutral the clutch switch appears to have no affect, and the bike acts as if the clutch is pulled in (wider injector pulse and increased RPM), whether the clutch is in or not.

-On the 2nd gen, no matter how you do the bypass, it’s possible you may see some adverse affects. Suzuki uses the clutch signal to add fuel while starting, but clearly the signal still has an effect even after the engine has started.

-Measurements shown here were taken while parked in the garage, not under normal riding conditions, so ymmv.

-On the 1st gen SV650 (carbureted) it's safe to simply bypass the clutch switch, as it has no affect on either ignition timing, or fueling.

Here's a video of how the measurements were taken, I hope it’s helpful!
http://www.youtube.com/watch?v=4_qnGJihHvM
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

Fabulous data TeeRiver - great job in photodoc'ing the process.

That's pretty conclusive.
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

-Suzuki uses the clutch signal to add fuel while starting, but clearly the signal still has an effect even after the engine has started.

-Measurements shown here were taken while parked in the garage, not under normal riding conditions, so ymmv.
Did anybody pass that to Andy ;D
Tee, did you try running bike through gears on stand? Can you monitor it that way?
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

Never mind Tee, just watched video. It is total bs, no way red is fastest :)
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

I missed this myself as I skipped over the test to get to the movie
But shared with my TL friend (whose video I referred you to in the initial thread discussion) and he picked this up:

-If you do a smart bypass (where you clip the clutch signal to the ECM to make it believe the clutch is never pulled in and then bypass the switch), the bike may be harder to start, since the ECM will not know to richen the fuel or bump up RPM. Many people have done this though, and reported no problem with starting.
-When the bike is in neutral the clutch switch appears to have no affect, and the bike acts as if the clutch is pulled in (wider injector pulse and increased RPM), whether the clutch is in or not....
;D

Does not dilute the findings at all however.
It does make it less of a consequence to cut the wire to the ECM however.
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

Very good stuff. Thanks for putting in the effort. It's nice to finally have a definitive answer about this.

So the proper method of bypass on a 2nd gen would be to cut or push out the pin for the Black/Yellow wire at the ECM? Anything else, like removing the wire from the starter solenoid and replacing it with a wire directly to the battery like D'Ecosse suggested previously?

This should be moved to the FAQ section.

:thumbsup:
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

Awesome work! As I suspected, just needed someone to confirm. And that's you!!! Way to go!

I vote to send it to FAQ's
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

Wow. This goes in my "stuff I wouldn't have thought of" file!
 

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Re: Clutch Switch Affect on Fuel Injector Pulse Width, (video)

I wonder if they do this to smooth out on/off throttle jerkiness that early FI bikes had?
 
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