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Old 05-15-2013, 11:00 AM   #61
jscottyk OP
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Originally Posted by roger 04 rt View Post
...
2) From experience with the Motronic and BMS-K ECUs, it would seem the likely time to Open the valve is during times when the BMS-K has commanded Open Loop (so that the Closed Loop routine doesn't get wrong answers) and has an enrichment routine running (e.g. you're accelerating or above 50/60 degrees throttle). The injected air will help the catalytic converter to oxidize the excess fuel at the richer AFR.
Ok, this is starting to make more sense. Will be really interesting to confirm this hypothesis.
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Old 05-15-2013, 11:11 AM   #62
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Resurrecting this thread. As my bike approaches the end of its warranty I'm thinking about a PC-5 with Autotune and full header. While researching, I found a couple of references to plugging the breather vents when using Autotune.

In the last couple of years has anyone decided to remove their Secondary Air System? Either as part of a PC-5 system or as part of simplifying the crank case breathing?
All I know is that I plugged the line as the decel popping was bonkers. Once plugged, popping gone. YMMV and all that yada yada.

FWIW, Remus pipe, Akro can, PCV and as of yet unhooked AT. As smooth as can be from idle through redline with no dead spots.

Need to hook up the AT, COBDR is 3 weeks away
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Old 05-16-2013, 10:54 AM   #63
roger 04 rt
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It would be great to know when this function is active.

Is there anyone who would be willing to connect a bulb (or 12V LED) across the two wires going to the SAS solenoid and then riding with the bulb in view so we could all get an idea when the SAS system is operational?

RB
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Old 05-16-2013, 11:19 AM   #64
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Originally Posted by roger 04 rt View Post
It would be great to know when this function is active.

Is there anyone who would be willing to connect a bulb (or 12V LED) across the two wires going to the SAS solenoid and then riding with the bulb in view so we could all get an idea when the SAS system is operational?

RB
I'd do it. Where is that critter located...???
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Old 05-16-2013, 01:55 PM   #65
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Originally Posted by ebrabaek View Post
... Do you know where that critter is located...???
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Originally Posted by roger 04 rt View Post
...No idea about its location. An LED would be good. I'll get back to you with the wire colors.
A couple of images for reference.

I think the valve that controls air to the SAS is #17 in this image.

Part #19 from the above images is #4 in this image.


The connector from BMS-K should attach to #17.
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Old 05-16-2013, 02:49 PM   #66
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Originally Posted by jscottyk View Post
A couple of images for reference.

I think the valve that controls air to the SAS is #17 in this image.

Part #19 from the above images is #4 in this image.


The connector from BMS-K should attach to #17.
We are all shure this is NOT a regular crank case vent system..... Someone knows that as it passes through the o-ring #3.... it in fact goes deep into the exhaust part of the cylinder, not just into the crank case......
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Old 05-16-2013, 02:56 PM   #67
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We are all shure this is NOT a regular crank case vent system..... Someone knows that as it passes through the o-ring #3.... it in fact goes deep into the exhaust part of the cylinder, not just into the crank case......
Well, it is definitely not regular but I understand #3 is the crankcase breather and is separate from the SAS. Discussed a bit here in the thread.

Hose #2 in the above diagram connects to the airbox.
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Old 05-16-2013, 04:45 PM   #68
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Well, it is definitely not regular but I understand #3 is the crankcase breather and is separate from the SAS. Discussed a bit here in the thread.

Hose #2 in the above diagram connects to the airbox.
I see.... #2 hose is for the crank case breather system, and #4 is for the SAS system. Funny thing though, I do not remember any internal parts protruding into the engine through the valve cover, as where the #4 hose connects to it..... Anyone have had the valve cover off recently that can verify this.......??????
I would buy that #2 is the SAS hose, and #4 is the crank case breather system......IE reversed....
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Old 05-16-2013, 05:55 PM   #69
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...I would buy that #2 is the SAS hose, and #4 is the crank case breather system......IE reversed....
I thought that at first (back in 2010... I've been bird-dogging this topic for sometime) but as I looked at the manual and fiche, started to doubt it.

Re-read JoelWisman's description of how the SAS works.
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...Next up is an on off solenoid valve. This valve is mounted to the right front of the air box. It mounts from the bottom and is clearly visible from the top of the air box. Secondary air would confuse the oxygen sensor were it flowing all the time, so this solenoid valve is switched on by the engine management computer (BMW speak=BMSK) when desirable and off when accurate O2 sensor readings are desired. Some have complained about the click this valve makes, some are louder then others, I've never seen this valve fail, the BMSK has trouble codes to communicate if this valve is stuck open, stuck closed, or unhooked.
He is referring to #17 in this drawing.



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...Next down the line is a reed valve. This valve is bolted to the valve cover. In essence it is a light weight high speed one way valve. This valve blocks the channel where second air is injected into the exhaust. One side of this reed valve has fresh filtered air at atmospheric pressure any time the second air solenoid is open. The other side has exhaust pressure. Exhaust pressure is not constant. Right as the cylinder exhaust valve opens, pressure goes up and exhaust accelerates through the exhaust system. Exhaust has mass, as the last of the exhaust leaves the cylinder, exhaust with mass is still flowing at high speed through the exhaust pipes. Since the cylinder is empty and exhaust valve closing, there is no longer any inlet to support continued flow and the exhaust begins slowing. The mass of the exhaust that was flowing forms a partial vacuum as it decelerates. This vacuum opens the reed valve and draws in secondary air.

He is referring to #5 (the valves) and #4 (how the valves are bolted to the cover).

Why BMW makes this so obtuse is beyond me! This topic is not covered in it's entirety in any single piece of published documentation that I have found.
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Old 05-16-2013, 06:00 PM   #70
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Erling, do you get decel popping? With the wide band 02 sensor any air injected will cause a bad reading, but you knew that already.
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Old 05-16-2013, 07:49 PM   #71
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Originally Posted by jscottyk View Post
I thought that at first (back in 2010... I've been bird-dogging this topic for sometime) but as I looked at the manual and fiche, started to doubt it.

Re-read JoelWisman's description of how the SAS works.

He is referring to #17 in this drawing.





He is referring to #5 (the valves) and #4 (how the valves are bolted to the cover).

Why BMW makes this so obtuse is beyond me! This topic is not covered in it's entirety in any single piece of published documentation that I have found.
I get the SAS system.... But are having a hard time buying the diagram as SAS. ( i might be an idiot at that though...) But as I had the valve cover off ( #6) I do not recall anything right under there that were in contact with the exhaust gasses. Think about it..... This thing (SAS) supposedly injects air into the exhaust slip stream....right..... There should be nothing right under the valve cover that has any contact with the exhaust system, as pictured above. That to me puts a positive ventilation into the crank case, known as a PCV. So to clarify..... I am certain Joel knows his stuff.....But I am not agreeing with all he says in the post referenced. I simply cannot see that right under the valve cover is exhaust pressure as the diagram above indicates. Pardon my ignorance, but to me, it does not add up. Holding back exhaust pressure right at the head is a big thing. Dang..... I wish I had looked at it more , when I had it off......
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ebrabaek screwed with this post 05-16-2013 at 07:58 PM
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Old 05-16-2013, 07:55 PM   #72
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Erling, do you get decel popping? With the wide band 02 sensor any air injected will cause a bad reading, but you knew that already.
I am still not sure the 8GS has air injected into the exhaust stream. I am very specific in saying this as such. Inject air into the exhaust stream.... That doesn't mean I am right..... Have been wrong many times before.... No popping on decell, anymore. It stopped with the pc-5/AT install. Like a switch.
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Old 05-16-2013, 08:06 PM   #73
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Read this article from 2008. It seems a pretty open and shut case.

http://www.webbikeworld.com/BMW-moto.../bmw-f-800-gs/
Nominally, the engine provides 85 HP at 7,500 RPM and at 5,750 RPM it sends 61 pounds-feet of torque to the sliding bearing based crankshaft.

Thanks to the regulated three-way catalytic converter and secondary air system, the twin also releases its power in a way that is environmentally friendly.

And the engine is balanced by BMW's system that is unique in standard motorcycle design: an additional swivel con-rod balances the first and second level mass forces and ensures that the two-cylinder functions with the minimum of vibrations.
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Old 05-16-2013, 08:18 PM   #74
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Read this article from 2008. It seems a pretty open and shut case.

http://www.webbikeworld.com/BMW-moto.../bmw-f-800-gs/
Nominally, the engine provides 85 HP at 7,500 RPM and at 5,750 RPM it sends 61 pounds-feet of torque to the sliding bearing based crankshaft.

Thanks to the regulated three-way catalytic converter and secondary air system, the twin also releases its power in a way that is environmentally friendly.

And the engine is balanced by BMW's system that is unique in standard motorcycle design: an additional swivel con-rod balances the first and second level mass forces and ensures that the two-cylinder functions with the minimum of vibrations.
Ok so more specific..... I am not convinced the diagram above puts air into the exhaust, sorry, I just cant see that. Into the crank case yes. Right under the valve cover are the valves, I fail to see the path from there into the exhaust system, thats all.....
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Old 05-16-2013, 08:36 PM   #75
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Ok so more specific..... I am not convinced the diagram above puts air into the exhaust, sorry, I just cant see that. Into the crank case yes. Right under the valve cover are the valves, I fail to see the path from there into the exhaust system, thats all.....
I agree, this is very confusing and the paths through the cover via the reed valves into the exhaust is a mystery. I cannot find a drawing that clearly shows this.

Seeking someone that has had one of these motors disassembled to chime in.
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