High Headwinds Stutter

[Rich82GS750TZ]

In most configurations, I believe the 2 vent tubes are to go up, over to the top of the airbox and terminate in still air, under and between about where the seat and fuel tank meet, where they should not be disturbed under normal conditions. But I suppose that even there, very strong winds from a certain direction could have an effect.

[danny01975]

In most configurations, I believe the 2 vent tubes are to go up, over to the top of the airbox and terminate in still air, under and between about where the seat and fuel tank meet, where they should not be disturbed under normal conditions. But I suppose that even there, very strong winds from a certain direction could have an effect.

That's how mine are configured. Im not sure if that's where the disturbance is occurring or from the opening at the bottom of the airbox. Do you know if the bottom of the airbox should be open, or if there's supposed to be a boot over the opening? I saw one airbox that had a boot that routed the intake closer to the top edge rather than taking air in from the bottom.

[Rich82GS750TZ]

Sorry, I do not know. Maybe someone else can describe or show the snorkel size/location in the stock airbox of a 82 GS1100GK

[dgates1]

Looks like that airbox should have a "snorkel" on the back. Don't see a separate part number for it. I had to find a decent used one for my GS850GL as the seal around the bottom hole was all blown out. Not having that could definitely affect the air turbidity. It does close that hole at the bottom and move the intake up to under the seat.

You can see the top of it peeking out from the back of the fiche here. Below parts 11-12-13.

https://www.adeptpowersports.com/oem-parts/1982-suzuki-gs1100gk-air-cleaner-assembly.html

[danny01975]

Looks like that airbox should have a "snorkel" on the back. Don't see a separate part number for it. I had to find a decent used one for my GS850GL as the seal around the bottom hole was all blown out. Not having that could definitely affect the air turbidity. It does close that hole at the bottom and move the intake up to under the seat.

You can see the top of it peeking out from the back of the fiche here. Below parts 11-12-13.

https://www.adeptpowersports.com/oem-parts/1982-suzuki-gs1100gk-air-cleaner-assembly.html

Ah ha! I thought I had seen an image like that before. From a different angle, for an 850 no less. And yea, you're right, I can see what appears to be the top edge of it in the fiche image.

Mine does not have that snorkel, and instead just has an open hole on the bottom. Not sure I'll ever be able to find that part, but I do have a 3d printer!

[dgates1]

I found a used one on eBay. Wasn’t perfect, but the bottom seal was in tact. I have the old one if you want some better photos or measurements. PM me if interested.

[81ZUKI75]

You may have cured your problem but here is a long discussion from 2013...I was having a similar issue at the time.

https://www.thegsresources.com/_forum/forum/technical-forums/performance-tuning-mods/63635-cross-wind-power-loss

[danny01975]

You may have cured your problem but here is a long discussion from 2013...I was having a similar issue at the time.
https://www.thegsresources.com/_foru...ind-power-loss

Nice! Lots of good information there. Who knew this was actually a thing! The part I found most interesting was the explanation about how the side winds cause a pressure equalization between the bottom and top of the jet causing the fuel flow to stop temporarily. I don't run pods (stock air box) and my vent tubes aren't blocked and are properly routed. However, the proper routing on my vent tubes are right behind and below the airbox. Right where the sidewind blows! So that could be something to look at.

Also, my airbox doesn't have that little snorkel on the back that routes the air intake up under the seat. Instead there's just an opening on the bottom where it pulls air directly from the bottom of the airbox. Also in the same spot that the air rushes in. Not sure which thing is the actual cause.

I haven't fixed it just yet, but I also haven't had any strong side winds. I have to wait for a really windy day, and drive at just the right direction, to test it. I did manage to 3D print a test snorkel piece that routs the air intake up instead of right from the bottom of the airbox. So we'll see how that works.

[Wingsconsin]

Just to throw in some additional data here

I have experienced that with my GS850GL 1983 -

I found the vent tubes were not well protected and this caused the vacuum imbalance I think -

I also think that I am a very large object that catches a lot of wind and causes resistance when the gusts blow against my chest - think sail.

[danny01975]

Just to throw in some additional data here

I have experienced that with my GS850GL 1983 -

I found the vent tubes were not well protected and this caused the vacuum imbalance I think -

I also think that I am a very large object that catches a lot of wind and causes resistance when the gusts blow against my chest - think sail.

Funny you should mention that. I have been chasing down a "stutter" at the transition between the pilot and needle handoff so I was double checking my float bowl heights (that's a whole different story) and after the bowl was filled I would gently blow into or apply light suction to the vent tubes and it would move the fuel level up and down. I'd do this to "stabilize" the level in the bowl. I also noticed when I'd plug the vent tubes so I could flip the rack upside down without all the fuel spilling out, the fuel level would rise.

All that to say, the vent tubes seem especially sensitive to changes in pressure. I'm sure it wouldn't take too much air (highway speed + cross winds) to either add pressure into the bowls or create a slight vacuum. And they are positioned perfectly for this to happen!