Worth buying Airbox boots?

[mpidsadny]

Hi,
I’m in the process of rebuilding a 1979 GS850 that I inherited from my father. It was last registered in 1998 and has been sat in a barn ever since.

The airbox boots seem soft enough and are not torn but I wonder if it’s worth buying a set. Are these boots as critical as the intake boots? I imagine these parts will become harder to find in the future so it might be nice just to have.

This is my first forum post so I apologize if I’ve made any errors!

 

[bwringer]

Yes, they're definitely worth buying fresh, and yes, they are extremely critical.

You won't believe the difference, and how much easier it makes carb work.

Make sure you get the right ones -- the 1979 slide carbs are a lot different than the 1980+ CV models.

 

[dpep]

New boots are always best if you can still locate a full set. Earlier this year I was only able to find right side ones for some reason and it was my left side ones that were in the worst shape.

You may want to try soaking your boots for a few days in a wintergreen oil and alcohol mixture. It will soften them up and restore their shape. That is what I had to do and it worked out well.

Here is a you tube explaining the process--quite simple.

https://www.youtube.com/watch?v=O4j7G9ry6uk

There are other variations of the wintergreen oil trick that use hot water or xylene and may give quicker results. I prefer the alcohol method because it will not harm the part if left in too long as the others can, It's also safe for your hands.

https://www.thegsresources.com/_forum/forum/technical-forums/general-maintenance/45964-wintergreen-oil-for-revitalising-rubber-par

Even if you locate new boots don't throw the old ones away. Try soaking them as above or at least store them for future use by you or someone here on the site. Rubber parts only get more scarce over time.

 

[93Bandit]

New boots are always best if you can still locate a full set. Earlier this year I was only able to find right side ones for some reason and it was my left side ones that were in the worst shape.

You may want to try soaking your boots for a few days in a wintergreen oil and alcohol mixture. It will soften them up and restore their shape. That is what I had to do and it worked out well.

Here is a you tube explaining the process--quite simple.

https://www.youtube.com/watch?v=O4j7G9ry6uk

There are other variations of the wintergreen oil trick that use hot water or xylene and may give quicker results. I prefer the alcohol method because it will not harm the part if left in too long as the others can, It's also safe for your hands.

https://www.thegsresources.com/_forum/forum/technical-forums/general-maintenance/45964-wintergreen-oil-for-revitalising-rubber-par

Even if you locate new boots don't throw the old ones away. Try soaking them as above or at least store them for future use by you or someone here on the site. Rubber parts only get more scarce over time.

Ah man! I wish I knew you could do this! I threw my old 750 boots in the trash because they were hard. Not cracked or torn, just hard. I bought new ones but soaking the old ones to have on hand as spares would have been nice. Oh well...

 

[mpidsadny]

New boots are always best if you can still locate a full set. Earlier this year I was only able to find right side ones for some reason and it was my left side ones that were in the worst shape.

You may want to try soaking your boots for a few days in a wintergreen oil and alcohol mixture. It will soften them up and restore their shape. That is what I had to do and it worked out well.

Here is a you tube explaining the process--quite simple.

https://www.youtube.com/watch?v=O4j7G9ry6uk

There are other variations of the wintergreen oil trick that use hot water or xylene and may give quicker results. I prefer the alcohol method because it will not harm the part if left in too long as the others can, It's also safe for your hands.

https://www.thegsresources.com/_forum/forum/technical-forums/general-maintenance/45964-wintergreen-oil-for-revitalising-rubber-par

Even if you locate new boots don't throw the old ones away. Try soaking them as above or at least store them for future use by you or someone here on the site. Rubber parts only get more scarce over time.

Thanks for the tip with the Wintergreen! I don't think I could ever throw anything away from this bike for this exact reason.

Thank you bwringer for your advice. I knew the intake boots and o-rings were critical but I had no idea the connection from airbox to carb was so important as well!

A new set of airbox hoses will be on their way shortly.

 

[rphillips]

This thread got me wondering. How much difference will there be in a set of these boots that have been sitting on a shelf for 20 yrs, vs a set that have been on a bike for 20 yrs?

 

[mpidsadny]

This thread got me wondering. How much difference will there be in a set of these boots that have been sitting on a shelf for 20 yrs, vs a set that have been on a bike for 20 yrs?

Honestly, I wouldn't know as this is my first time digging into a GS. However, things like extreme temps, sun exposure, exposure to harsh fumes (gasoline), vibrations, stress due to the weight of the carbs all could degrade the rubber on the boots.

 

[rphillips]

I thought about those things, figured sunlight would have the biggest effect on the rubber, but on a bike they would rarely have any sunlight on them, heat & cool would probably be 2nd & fumes, these being upstream of the carbs would be minimal, probably more the smell than fumes... I dun'no, just wondering.

 

[mpidsadny]

I thought about those things, figured sunlight would have the biggest effect on the rubber, but on a bike they would rarely have any sunlight on them, heat & cool would probably be 2nd & fumes, these being upstream of the carbs would be minimal, probably more the smell than fumes... I dun'no, just wondering.

It's a great question to ask and I suppose I could test it out. New unopened airbox boots vs 13500 km that have sat for the past 24 years!

 

[dorkburger]

I've seen a few posts here over the years where the rubber "trumpets" on the inlet side of the airbox boots sucked in on themselves causing running issues.

I slathered the ones sitting on my shelf with Vaseline as noted a couple of years ago. They may be slightly better, but if nothing else, they haven't gotten worse. The trumpets were slightly oblong, and I set baseballs on them to bring them back into shape. Certainly not a quick fix though.

 

[bwringer]

Old rubber parts, if they've been left inside the sealed plastic bag from the factory, generally are fresh as a daisy.

If some numpty took them out of the bag for some dumb reason and left them exposed to air inside the cardboard box for a few decades, they may be a little bit hardened or have some surface oxidation, but generally are OK. Of course, with metal parts, corrosion can be an issue for parts left exposed to air like this.

One thing that's happened to me a few times with "NOS" (new old stock) parts is that some long-ago moron replaced a part, then for reasons known only to morons, placed the failed old part carefully inside the original box, then put it back on the shelf. Decades later, said moron is creating chaos in some other shop or the afterlife, and someone who doesn't know or care puts the part on eBay as NOS. So you have to be very careful about that sort of thing.

There are only a few situations where keeping a broken or failed part for 20 years makes any sense at all, but it's pretty common.

 

[Gorminrider]

My airbox boots are all in good shape flexibiltiy-wise and they'd be way down the list as "spares" but the vaseline trick is a very good idea! and on manifold boots too.

... there is one thing per airbox boots that I think it's worth adding here- they're just soft enough to get a bit folded when putting on the carbs and just possibly partially blocking the little idle air port or just not clamping properly, so do be careful when fitting on . They plastic takes a "set" if they've been forced on badly so it's worth a look before forcing them back on...

 

[letchworth rider]

Also check the airbox for warpage. It was a bigger issue than the boots on mine. Used a combination of and expander from inside and a heat gun to get straight. This winter I fixed a few things I did not get the first time. Paint, fuel feed orings, stripes, carb balance etc.

 

[bwringer]

Also check the airbox for warpage. It was a bigger issue than the boots on mine. Used a combination of and expander from inside and a heat gun to get straight. This winter I fixed a few things I did not get the first time. Paint, fuel feed orings, stripes, carb balance etc.

Agreed. Airboxen like to sort of "sag" in the middle, just where you can't see whether the boots have made it onto the carbs or popped off. Even folding one lip under can have a large effect.

You can CAREFULLY heat the plastic to soften it with a heat gun, then apply pressure from the inside while it cools to end up with a straight airbox. Go very very slowly and keep the heat moving so you don't go too far. All you need is a little bit soft so it'll move and then stay that way as it cools and hardens.



No one asked, but speaking of reshaping airboxen... on the 1100E and perhaps a few other 16V bikes with a two-piece airbox, you can use a heat gun on one specific corner of the rear airbox to soften the corner and flatten it just a little bit (press it into a piece of wood. If you're careful it will look factory, and of course this tiny change doesn't affect airflow at all. (Which corner I can't remember; you'll know what I mean if you've ever wrestled this damn thing out before, there's one specific corner with gouges all over it that hangs up.) This will make it 1,000% easier to remove the rear airbox and get to the battery.