Engine braking with emergency shutdown. - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
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post #1 of 22 Old 08-03-2018, 04:11 AM Thread Starter
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Engine braking with emergency shutdown.

Hi all!
My k4 650 has got a significant difference when engine braking with the ignition on and off. So the engine is, i suppose, braking with "idle throttle". Is it safe to cut the throttle with emergency shutdown or would the injection system still be injecting fuel into the engine? I've been trying to guess that from the electric schema, but I wasn't lucky yet.
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post #2 of 22 Old 08-03-2018, 08:03 AM
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When you cut the "ignition" there will not be fuel sprayed into the engine. I don't really see the need to do much worrying about needing an "emergency" braking system, but it would slow you somewhat.

After all, you have two completely separate braking systems on the bike as delivered from the factory. One of them might fail, but the chance of both going is just too small for me to even think about.

I used to hit the kill switch on 2 cycle dirt bikes going down hills and open the throttle wide open. On steep down hills it worked better than the rear brake, especially if both feet were down trying to keep you upright!
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'12 DL 650 '14 BMW R 1200 RT

WERKS modified clutch baskets for DL and SV 1000's.
The BEST in chudder control, noise control, and lasting durability! AVAILABLE HERE: www.werksparts.com

Have questions about the clutch in your DL or SV 1000? E-mail Terry [email protected]
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post #3 of 22 Old 08-03-2018, 08:26 AM Thread Starter
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Exactly, for these special situations, like going down a long hill and needing just a bit more engine breaking, or the one you described. Plus here in Switzerland there's a lot of steep roads, and I get better satisfaction of fuel saving with knowing the fuel is completely cut off
Thanks!
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post #4 of 22 Old 08-03-2018, 11:32 AM
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Interesting concept. In all my days I never thought of shutting off the engine to get more braking, My brakes and a lower gear suffice to reduce my forward movement quite well enough. Besides, sometimes I'd want that immediate throttle response to better control my bike.
Some folks like to have races when coasting. Get high enough on a mountain road and see if you can carry enough speed through the turns and ups and downs to make to the bottom without running the engine.
Not my bag but Billy in the King of GMR as the story goes.
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post #5 of 22 Old 08-03-2018, 11:59 AM
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Fuel injected engines in general stop injection during decel until rpm approaches 200-400 rpm of idle speed. This is done as an emission control measure, and also as a fuel economy aid.
I've watched injection patterns on labscopes and viewed a base pattern that looks like a lower-case "r", acceleration and the top of the "r" elongates as the injector duration(time in milliseconds the injector is held open by the engine control unit)increases, chop the throttle and the pattern disappears until rpm approaches base idle speed.
Some engines with secondary throttle plates vary their opening and closing angles to adjust engine vacuum on decel. In a discussion with the Suzuki factory service rep earlier this year he said that one of the changes in programming for the '14-'15 DL1000 ECU recall was to open the secondaries to soften engine braking during decel.
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post #6 of 22 Old 08-03-2018, 01:37 PM
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Quote:
Originally Posted by MAZ4ME View Post
Some engines with secondary throttle plates vary their opening and closing angles to adjust engine vacuum on decel. In a discussion with the Suzuki factory service rep earlier this year he said that one of the changes in programming for the '14-'15 DL1000 ECU recall was to open the secondaries to soften engine braking during decel.
Interesting, as every engine I have experience with actually has increased engine braking when more air is allowed into the cylinder with no fuel or spark to fire it? Pulling in the air, then forcing it out takes work which is energy. Engines with cylinder deactivation are closing valves to prevent air pumping losses on cylinders not being used to make power. This eliminates pumping losses. Now if they were also introducing a small amount of fuel with this air, that would indeed "soften" engine braking.

'12 DL 650 '14 BMW R 1200 RT

WERKS modified clutch baskets for DL and SV 1000's.
The BEST in chudder control, noise control, and lasting durability! AVAILABLE HERE: www.werksparts.com

Have questions about the clutch in your DL or SV 1000? E-mail Terry [email protected]
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post #7 of 22 Old 08-03-2018, 01:50 PM
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Will hitting the kill switch also shutdown your ABS or Traction Control? Assuming you unit is so equipped...

When I hit the kill switch (usually how I shut down when stopping at a gas pump as it provides me with the means to stop the motor without moving either hand), I see that a bunch of warning lights come on but I've never looked closely enough to see which systems go down. I am pretty sure that hitting the kill switch on my DL1000A also kills the fuel pump and radiator fan. I assumed therefore that it kills everything except the lights. I'll have to pay closer attention or review the wiring diagram.
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post #8 of 22 Old 08-03-2018, 02:36 PM
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I am not recommending anyone shut off/kill the engine while on the street to gain additional braking. There is nothing about that, to me, that would be safer than simply learning to use the front and rear braking systems effectively.
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'12 DL 650 '14 BMW R 1200 RT

WERKS modified clutch baskets for DL and SV 1000's.
The BEST in chudder control, noise control, and lasting durability! AVAILABLE HERE: www.werksparts.com

Have questions about the clutch in your DL or SV 1000? E-mail Terry [email protected]
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post #9 of 22 Old 08-03-2018, 02:56 PM
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Quote:
Originally Posted by realshelby View Post
Interesting, as every engine I have experience with actually has increased engine braking when more air is allowed into the cylinder with no fuel or spark to fire it? Pulling in the air, then forcing it out takes work which is energy. Engines with cylinder deactivation are closing valves to prevent air pumping losses on cylinders not being used to make power. This eliminates pumping losses. Now if they were also introducing a small amount of fuel with this air, that would indeed "soften" engine braking.
The Rep said that there were complaints of abrupt or harsh decel, possibly contributing to the stalling issue. By opening the secondaries, and possibly the IAC, vacuum on decel is relieved, less "pulling" on the pistons, similar to a compression loss is less force applied to the piston.
Still, unless the primaries are opened full vacuum is behind the throttle plates, unless the IAC goes open on decel. I havent monitored any of the signals at the ECU, havent had a need to. But I can say that decel is smoother after the recall than before. As idle speed is also 200 rpm higher both cold and hot, air has to getting past the primary throttle plates somehow, which will reduce engine vacuum.
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post #10 of 22 Old 08-03-2018, 05:15 PM
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" stop the motor without moving either hand)"

I roll up to the pump and dump the clutch and stop the motor. It helps to hold the brake too.

Is killing the engine while rolling on par with how a Jake Brake works on Diesels?
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