Where is slow air shutoff valve located


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GWClint
Posts: 12
Joined: Sun Sep 10, 2017 7:14 pm
Location: Strathmore, Alberta ,Canada
Motorcycle: 1985 Honda Gold Wing LTD

Where is slow air shutoff valve located

Post by GWClint » Tue Apr 03, 2018 9:45 am





Where is the slow air shutoff valve located on the 85 LE?



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Rednaxs60
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Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD (X2), 2008 GL1800 (sold)

Re: Where is slow air shutoff valve located

Post by Rednaxs60 » Tue Apr 03, 2018 10:41 am

What slow air valve shut off? There is an Idle Air Control (IAC) valve located on the right side of the engine just below the chrome CFI cover. This valve is primarily used for the fast idle on start.

Here's a picture of the valve:


The idle air control valve (air valve) is connected in parallel with the fuel pump and has a 12 VDC signal going to the valve - confirmed that today. The water lines that are connected are to provide hot coolant flow through the valve to prevent freeze up of the valve in cold climates. Since most do not ride these bikes when it is too cold so an IAC valve without the water connections should work just as well.

Here is a picture of the internals:


Cheers
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

GWClint
Posts: 12
Joined: Sun Sep 10, 2017 7:14 pm
Location: Strathmore, Alberta ,Canada
Motorcycle: 1985 Honda Gold Wing LTD

Re: Where is slow air shutoff valve located

Post by GWClint » Tue Apr 03, 2018 4:35 pm

Thank you Rednax60, do you know does this serve the same purpose as the low air shutoff valve on the regular 1200?
i have a situation where the engine performs properly well but at idle speeds it sounds like it is wheezing, best way i can describe it, and as speed increases, the sound gets less and disappears above about 1500 rpm

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Rednaxs60
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Joined: Wed Nov 18, 2015 12:44 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD (X2), 2008 GL1800 (sold)

Re: Where is slow air shutoff valve located

Post by Rednaxs60 » Tue Apr 03, 2018 8:05 pm

GWClint wrote:
Tue Apr 03, 2018 4:35 pm
Thank you Rednax60, do you know does this serve the same purpose as the low air shutoff valve on the regular 1200?
i have a situation where the engine performs properly well but at idle speeds it sounds like it is wheezing, best way i can describe it, and as speed increases, the sound gets less and disappears above about 1500 rpm
Will have to look into this but I do not believe it does. There is also a difference between the CDN versions and US models. Here is a thread regarding this valve: viewtopic.php?t=17995 It apparently is used to enrich the fuel system to prevent popping/backfiring during decelleration. The IAC valve we have does have a similar use as well, does it differently. The IAC valve allows a small amount of air to bypass the throttle plates on deceleration preventing the engine from being starved of air when the throttle plates are closed.

When I had the IAC valve apart, I noticed that it is never fully closed.

You have a "wheezing". It is an old bike you know. :lol: Seriously, where is the wheezing emanating from? I would take the shelter off and take it out for a run to determine the location.

Would also recommend cleaning the throttle plates. You do this by taking off the shelter, remove the air filter, and using carb cleaner - spray into each cylinder air intake.

Just had an issue with my bike missing and engine stopping. Changed the fuel filter, made sure the fuel pump inlet screen was clean, and soaked the gas cap overnight in a WD40 cleaner/degreaser. These bikes vent through the gas cap and this is good maintenance as well.

Cheers
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

GWClint
Posts: 12
Joined: Sun Sep 10, 2017 7:14 pm
Location: Strathmore, Alberta ,Canada
Motorcycle: 1985 Honda Gold Wing LTD

Re: Where is slow air shutoff valve located

Post by GWClint » Thu Apr 05, 2018 10:12 pm

Thanks again Rednaxs, the more I think about it the IAC valve is idle air cutoff valve. The difference between it and the slow air cutoff valve, on the regular 1200 is that the it is electronically controlled and the other is vacuum driven. In either case if that valve dosent open when the throttles close the engine will be air starved.
We are having a winter from hell here this year, and the bike is in an unheated shop so I'm waiting for warm weather to start it and prove the theory by just taking the air line off on the outlet side and see if the wheezing stops

DaveO430
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2004 Suzuki DR200

Re: Where is slow air shutoff valve located

Post by DaveO430 » Fri Apr 06, 2018 7:05 am

What the IAC valve is for is to provide extra air when cold, has nothing to do with anything else. They were used on just about everything with early electronic injection. Fuel injection does not need an air cutoff because injection is stopped during deceleration. The wheezing sound you hear is probably from the secondary air injection.

GWClint
Posts: 12
Joined: Sun Sep 10, 2017 7:14 pm
Location: Strathmore, Alberta ,Canada
Motorcycle: 1985 Honda Gold Wing LTD

Re: Where is slow air shutoff valve located

Post by GWClint » Fri Apr 06, 2018 10:24 am

Thank you Dave for your input. However engines don't need extra air when cold, they need less because cold air is more dense, hence the need for a choke on the engines with carborators, to reduce the amount of air when cold. I agree fuel is reduced to idle requirements when the throttle is closed but at that point the engine needs a source of air because the throttle plates are closed. That source of air for the regular 1200 is the slow air cutoff valve, and I believe the source of air for the injected 1200 is the IAC valve. Secondary air injection?? There is no air injection primary, or secondary, it is drawn in buy the engine through the throttle bodies. When the throttle plated are closed it needs an alternate source of air, and I beleive that the slow air valves are that source. Now that I know where that valve is ( thanks Rednaxs ) I will prove out the theory when I start the bike when it warms up

DaveO430
Posts: 779
Joined: Fri Jan 02, 2015 7:28 pm
Location: Amity. Ar
Motorcycle: 2010 GL1800
2004 Suzuki DR200

Re: Where is slow air shutoff valve located

Post by DaveO430 » Fri Apr 06, 2018 4:29 pm

GWClint wrote:
Fri Apr 06, 2018 10:24 am
Thank you Dave for your input. However engines don't need extra air when cold, they need less because cold air is more dense, hence the need for a choke on the engines with carborators, to reduce the amount of air when cold. I agree fuel is reduced to idle requirements when the throttle is closed but at that point the engine needs a source of air because the throttle plates are closed. That source of air for the regular 1200 is the slow air cutoff valve, and I believe the source of air for the injected 1200 is the IAC valve. Secondary air injection?? There is no air injection primary, or secondary, it is drawn in buy the engine through the throttle bodies. When the throttle plated are closed it needs an alternate source of air, and I beleive that the slow air valves are that source. Now that I know where that valve is ( thanks Rednaxs ) I will prove out the theory when I start the bike when it warms up
Whatever you think.



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