Gl 1200 Secondary Air System-USA models

[backlander]

Thanks Bronko, good work.

 

[Ansimp]

Will take you advice, :thanks: Bronko

 

[dan filipi]

Very cool!

So bottom line here is what, this mod eliminated a lean condition?

 

[Steve83]

Question - do you think the huge advance in performance is mainly due to the removal of the secondary air system, or to all the work you've done on the carbs? I can't imagine how the air system, which is completely powered by vacuum pulses in the exhaust ports, and draws in fresh air from the plenum, would have much, if any, affect on performance. Just a thought...

 

[Ansimp]

Unless some how the fresh air is being contaminated with exhaust gas...

 

[bronko37]

Steve83 » Sun Mar 08, 2015 7:03 pm[/url]":36om7b5g]
Question - do you think the huge advance in performance is mainly due to the removal of the secondary air system, or to all the work you've done on the carbs? I can't imagine how the air system, which is completely powered by vacuum pulses in the exhaust ports, and draws in fresh air from the plenum, would have much, if any, affect on performance. Just a thought...

Now I did indeed rebuild the carbs using a Randakk kit. I also solved the backfire issue Dan. The backfire issue was as I assumed it always was, a faulty slow air cuttoff valve. When rebuilding the carbs my finding was that they were perfectly clean internally. I found no clogging, no varnish, no anything that would lead me to believe that I would get any type of performance increase from my rebuild. My rebuild was initially driven by the presumption that I had a vaccume problem that was most likely in the slow air cuttoff valve. I am a believer in "make it right while ur in there" so thatis why I purchased the entire rebuild kit. Point being the only thing that changed is the secondary air system was eliminated. I whole heartedly believe that the seat of the pants feel I am getting is from the elimitanion of the secondary system.

Now would I go tearing my bike apart for the sole purpose of eliminating this system, perhaps, depending upon the individual and how much "fun" you have working on the bike. I thoroughly enjoyed myself. If I ever needed to service my carbs or pull the rack for any reason there would be no chance that I would leave the secondary air system in place.

I guess as others also do this mod we will gather more opinions but the difference on the throttle is in my opinion profound.

 

[Steve83]

Ansimp » Sun Mar 08, 2015 5:38 pm[/url]":14samokg]
Unless some how the fresh air is being contaminated with exhaust gas...

There are check valves on all 4 tubes. If one or more were bad, this could be an issue. It would show itself by soot in the intake plenum, at the fresh air port. It would then be an EGR system - sort of...

Maybe I'll experiment on the 1200 engine I have, but it's on a stand, so I won't be able to get a "seat-of-the-pants" evaluation.

 

[dan filipi]

Your results got me to thinking about how I plugged the secondary head tubes, I simply used a rubber hose to connect the 2 together on each side.
Wondering if this could have affect on exhaust back pressure especially right there where these head ports sit right at the exhaust valve.
Hmm.

 

[Steve83]

This reminds me of the late 60s and early '70s when we'd pull all the smog parts off the car engines. I never noticed any performance improvement, but it sure made 'em easier to work on!

 

[bronko37]

dan filipi » Sun Mar 08, 2015 8:30 pm[/url]":1mqbw4zh]
Your results got me to thinking about how I plugged the secondary head tubes, I simply used a rubber hose to connect the 2 together on each side.
Wondering if this could have affect on exhaust back pressure especially right there where these head ports sit right at the exhaust valve.
Hmm.

Well Dan, there are vacuum lines that connect the secondary to the slow air and then to the nipple on intake 4. Could be an issue there if you don't have a line directly from the slow air to intake 4. Also the afterburn valve may still be opening? I would just pull the whole thing off if u ever take the rack out.

 

[bronko37]

Steve83 » Sun Mar 08, 2015 8:36 pm[/url]":3f49y1zy]
This reminds me of the late 60s and early '70s when we'd pull all the smog parts off the car engines. I never noticed any performance improvement, but it sure made 'em easier to work on!

I think it would be tuffer to notice anything on a car just because of the weight factor. All of your senses get used on a bike so even minor changes are easy to notice.

 

[rube]

Hi,

I’m working on getting a “basket case” 1985 GL1200i I just bought back on the road.
I just pulled the carbs and am going through them. The secondary air system made pulling the carbs a bit of a pain. As I am thinking I may need to have the carbs out again as I work on this bike I would like to remove the secondary air system to make removing and installing the carbs easier.
On other bikes I have worked on with similar ( aka P.A.I.R. Systems) I have been able to ring block off plate kits, but I have not been able to find a similar kit for the GW.
Can anyone point me to a source for the plugs from this thread (or something similar)? I can make the air box block off plate, but do not have a metal lathe to make the plugs.
Thank you for all the great information on this site!
rube

 

[Dusterdude]

There is not a kit that I'm aware of,I filled the hole with epoxy when I did mine.

Sent from my LM-X420 using Tapatalk

 

[rube]

Dusterdude » Today- 5:59[/url]":ud4o2cis]
There is not a kit that I'm aware of,I filled the hole with epoxy when I did mine.

Sent from my LM-X420 using Tapatalk

Hi,

And the epoxy has held up fine?
I cut the tube off of one of the stock head inserts and am currently looking for a freeze plug or aluminum rod of the right size to block the hole on the side. A 5/16 drill bit shank fits in there snuggly.
If I can find some 5/16 aluminum rod stock at the hardware store I could secure it in the side hole with some JB weld and then smooth it off.
A rubber plug might even work?
I could then rotate the repaired portion in towards the inside of the bike where it would be covered and not visible from the outside.
I also am thinking about plugging with a steel rod from below and welding, but figure the heat would destroy the chrome.
I’ll probably try the JB weld.

How does that plan sound?

 

[rube]

This is what I came up with.
A 5/16 set screw which kind of threads in and that I will seal in there with JB Weld.

rube

 

[dan filipi]

rube » 13 minutes ago[/url]":d1jl80mu]
This is what I came up with.
A 5/16 set screw which kind of threads in and that I will seal in there with JB Weld.

rube

Is there any pressure or heat from those ports? I don't remember from when I closed them off.

 

[rube]

dan filipi » Yesterday- 14:07[/url]":3cu6bef3]

rube » 13 minutes ago[/url]":3cu6bef3]
This is what I came up with.
A 5/16 set screw which kind of threads in and that I will seal in there with JB Weld.

rube

Is there any pressure or heat from those ports? I don't remember from when I closed them off.

I’m not sure how much pressure or heat there is.
I don’t think there is much though.

 

[Dusterdude]

rube » 13 minutes ago[/url]"ben3uuw]
This is what I came up with.
A 5/16 set screw which kind of threads in and that I will seal in there with JB Weld.

rube

Is there any pressure or heat from those ports? I don't remember from when I closed them off.

No,I used epoxy on mine.

Sent from my LM-X420 using Tapatalk

 

[alanc1100]

I did the cut and weld up like in post #3. I had to seal the valve hole in the center section. Cleaned and rebuilt my carbs with Randakks kit. Put it all back together and tuned the carbs. Took it out for a spin and massive backfiring! I worked on the mod for a couple weeks to no avail. I just could not make it stop backfiring. So, I used the spare carb set I have and redid my carbs to put it all back the way it was. I still haven’t finished getting it back together yet. Winter in south Puget Sound sucks! Rain, rain, rain! Any who, the mod failed for my bike. You guys can do what you want, but I’m going back stock.

Alan