Topic: Softening hard carb boots

[05c50]

I have intake boots for 750A (all years) and 550F airbox boots ready to ship. I'll have 550K airbox boots and 750K intake boots in about a week. I should have 78 750F intake boots soon. 

..........Paul

so are the 750A boots the same as the 77-78 K boots??

No. The 76A is different from the 77/78A. The 77/78 K is different then the early K, The F is different from all the others........and the list goes on

..................Paul

[bubbafun101]

I did what Hondaman did. Rounded up all the boots (8 sets). Next I poured my 4 oz of Wintergreen into the can and placed 2 sets of boots into it. Next I poured Xylene to cover them. Left till soft. Repeat with same mix. A couple of the boots swelled, but returned to normal size in a couple of days. Worked like a charm. I bagged them in sets of 4, tossed them in the carburator box and done. Near as I can tell there is no magical mix ratio.

[tbpmusic]

I did what Hondaman did. Rounded up all the boots (8 sets). Next I poured my 4 oz of Wintergreen into the can and placed 2 sets of boots into it. Next I poured Xylene to cover them. Left till soft. Repeat with same mix. A couple of the boots swelled, but returned to normal size in a couple of days. Worked like a charm. I bagged them in sets of 4, tossed them in the carburator box and done. Near as I can tell there is no magical mix ratio.

The wintergreen oil is expensive and irrelevant.
The process will work the same with xylene only, and be a lot cheaper too.
I was shocked that a tiny bottle of wintergreen would cost so much - so I proceeded without it, got great results........

[cookindaddy]

As long as you got it done.

The wintergreen oil here is $5 and works well without the xylene (which is hard to get here).

Go figure

[steelpig]

I did my boots in acetone/nail polish remover.  I left them in for a day.  They swells by 20% but returned to normal in 24 hours.  They are as soft as new.

[Kemp]

I tried Wintergreen and water mix to soften 6 sets of 550 and 650 carb boots. The water method was offered as an alternative to xylene (which you should not heat). I used 8 ounces of Wintergreen (bought a local pharmacy) mixed with about a gallon of water (boots completely submerged) and heated the whole deal on the barbecue to the point where little bubbles were forming on the boots. Kept it at that temp for about 1 hr stirring off and on to keep the wintergreen oil mixing with the water and not settling out. This process worked really well. The boots were initially rock hard and basically unusable. Now all the boots are quite soft and flexible. They are at least as flexible as NOS boots. I had no issues with swelling but the smell of wintergreen does persist for awhile. I did these boots 3 weeks ago and there has been no change in their flexibility, still soft, pliable and fully usable. The smell is diminishing and isn't bothersome. You should do this process outside though as the odor would linger for weeks indoors, maybe longer! I was skeptical of this process at first but am now a total convert. Highly recommend if you want your carbs to seal properly and be easy to install and remove.

[HondaMan]

I tried Wintergreen and water mix to soften 6 sets of 550 and 650 carb boots. The water method was offered as an alternative to xylene (which you should not heat). I used 8 ounces of Wintergreen (bought a local pharmacy) mixed with about a gallon of water (boots completely submerged) and heated the whole deal on the barbecue to the point where little bubbles were forming on the boots. Kept it at that temp for about 1 hr stirring off and on to keep the wintergreen oil mixing with the water and not settling out. This process worked really well. The boots were initially rock hard and basically unusable. Now all the boots are quite soft and flexible. They are at least as flexible as NOS boots. I had no issues with swelling but the smell of wintergreen does persist for awhile. I did these boots 3 weeks ago and there has been no change in their flexibility, still soft, pliable and fully usable. The smell is diminishing and isn't bothersome. You should do this process outside though as the odor would linger for weeks indoors, maybe longer! I was skeptical of this process at first but am now a total convert. Highly recommend if you want your carbs to seal properly and be easy to install and remove.

Actually, that smell is an improvement in my garage!

[Really?]

Make sure you check your boot clamps after a while.  When they shrink, you may have to tighten them up again.  I had to on mine.  Then I had to get new boot clamps because they did not get tight enough.

[wilson889]

after all these results using the wintergreen oil, how long will they last being soft?? some have said only a couple of minutes.. any estimates of time?

[cookindaddy]

I've been following these threads about the wintergreen treatment and done it now myself quite a few times.

I don't recall anyone saying it only lasts a few minutes?? There is some variation in the way it is done and the original condition of the rubber parts. In my experience the softening is permanent or lasts at least months or long enough to reinstall the part without leaks in the case of carb boots. It is difficult to say if the boots are still soft after a season of riding since I haven't taken them off the engine yet but I did remove the carb rack for some service last week and the boots are still pliable at that end (not the hot end) and they sealed up nicely.  Other parts I have treated (the oil pressure switch boot) are still soft from last year.

[Really?]

My boots are still softer than before.  They just shrunk to the point where I just went ahead and got new hose clamps after about a month.

[wilson889]

oh ok, sounds great, my mistake 

[xlaris]

Speaking of boot clamps..where do you find these things? I want something nice and aftermarket I was thinking of using nice hose clamps but dont think the curves will match up.

oh Im also new by the way Xavier out of los angeles 

[Really?]

OEM is expensive but there is a guy on eBay that sells nice clamps for much cheaper. They are not slotted and they are flat most of the way around. So, it looks like a band instead of a hose clamp.

What looks like slots are grooves.

I need to find him on there and I will let you know.

[Really?]

Here is the eBay auction. Maybe he has more.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=150502898866

Fast shipping too.

[xlaris]

sweet!!

[jwk1414]

I fought and fought to get the carbs off of my bike a few weeks and eventually sprayed them down with WD40, and they popped right off.  Carbs are ready to go back on but now I can't get the dang things to stay in the boots! They fall out with the slightest touch and I cant get any vacuum going to start the bike. Do I just need to invest in new boots or should I try these methods?

[PavelGee]

Hi, everyone.
This is Pavel from NY.
I recently got my first bike(a small project) 1978 cb750k (k8)
And lo and behold... I learn about the imposibility to get the 2 and 4 carb insulators(boots).
So, not giving up I ordered two new sets of 1 and 3.
Took the old cracked, broken rocks of carb boots off and put the correct new ones in.
Then the fun began - the 2 and 4, although exact mirror images of 3 and 1, are not interchabgable - due to the vertical incline of the intake openings (so they are tilted both horizontally to reach the wider carbs; and vertically for no apparent reason other then improved mixture flow).

When flipped around the engine side of the boot points up and to the right.... ugh
Anywho, I didnt give up then either - I flipped all four boots ever so slightly to come closest possible to a flat and even fit with the carbs. Put everything together and there was improvement, but no way of telling wether I got sufficient sealing.

Can you guys recommend a way to tell if I am losing vacuum at the boots before I look into carb tuning?

Oh, and of course, I am looking for new boots 16112-405-000 and 16114-405-000 or home made versions. I'll take pics when I take carbs off again to show what I am on about for others in my shoes.

[750K8 Kev]

Hi, everyone.
This is Pavel from NY.
I recently got my first bike(a small project) 1978 cb750k (k8)
And lo and behold... I learn about the imposibility to get the 2 and 4 carb insulators(boots).
So, not giving up I ordered two new sets of 1 and 3.
Took the old cracked, broken rocks of carb boots off and put the correct new ones in.
Then the fun began - the 2 and 4, although exact mirror images of 3 and 1, are not interchabgable - due to the vertical incline of the intake openings (so they are tilted both horizontally to reach the wider carbs; and vertically for no apparent reason other then improved mixture flow).

When flipped around the engine side of the boot points up and to the right.... ugh
Anywho, I didnt give up then either - I flipped all four boots ever so slightly to come closest possible to a flat and even fit with the carbs. Put everything together and there was improvement, but no way of telling wether I got sufficient sealing.

Can you guys recommend a way to tell if I am losing vacuum at the boots before I look into carb tuning?

Oh, and of course, I am looking for new boots 16112-405-000 and 16114-405-000 or home made versions. I'll take pics when I take carbs off again to show what I am on about for others in my shoes.

If you haven't figured it out already, you want to spray the boots at idle with some starter fluid.  You want to listen for a change in RPM as your spraying.  If you have a leak, the starter fluid being sucked in will compensate for a lean mix(to much air).  I am going through the same bs with my K8, I've been looking for new boots, or nice used boots for months...damn bike, it's always something with this thing.  I may just try the wintergreen treatment, don't have a choice at this point if I want to ride my bike again this year.

[madrahn]

I also have a 78.  Does anyone know if changing out the carbs will mean that the earlier carb boots can now be used?  Basically are the 77 and 78 carbs the reason the boots are different or is it the connection at the engine?  I thought of replacing the carbs with some 29mm anyway but I'm hoping the older carb boots will work so that I can actually order them instead of trying to reinvigorate the old boots.

[mick7504]

I did what Hondaman did. Rounded up all the boots (8 sets). Next I poured my 4 oz of Wintergreen into the can and placed 2 sets of boots into it. Next I poured Xylene to cover them. Left till soft. Repeat with same mix. A couple of the boots swelled, but returned to normal size in a couple of days. Worked like a charm. I bagged them in sets of 4, tossed them in the carburator box and done. Near as I can tell there is no magical mix ratio.

The wintergreen oil is expensive and irrelevant.
The process will work the same with xylene only, and be a lot cheaper too.
I was shocked that a tiny bottle of wintergreen would cost so much - so I proceeded without it, got great results........

That's all I've ever done with them too.
Xylene and a shot of Tranny fluid in a large glass jar.
They turned from bricks into pliable boots after 4/5 days soaking.
They'll still be fine to use.

[Blackandsilver]

I did what Hondaman did. Rounded up all the boots (8 sets). Next I poured my 4 oz of Wintergreen into the can and placed 2 sets of boots into it. Next I poured Xylene to cover them. Left till soft. Repeat with same mix. A couple of the boots swelled, but returned to normal size in a couple of days. Worked like a charm. I bagged them in sets of 4, tossed them in the carburator box and done. Near as I can tell there is no magical mix ratio.

The wintergreen oil is expensive and irrelevant.
The process will work the same with xylene only, and be a lot cheaper too.
I was shocked that a tiny bottle of wintergreen would cost so much - so I proceeded without it, got great results........

That's all I've ever done with them too.
Xylene and a shot of Tranny fluid in a large glass jar.
They turned from bricks into pliable boots after 4/5 days soaking.
They'll still be fine to use.

I gotta do mine now too.... How long do they stay soft for with the xylene and tranny fluid?


Win some lose some, it's all the same to me.

[apehanger 550]

  If I had this to do over,I would have used a device to keep the carb boots from swelling so much. What I would recommend is to lightly restrain the OD of the boots with a PVC pipe or possibly use a wrap of thin metal like a cut pop can and then the original band clamps to keep the pressure even.
  Mine swelled up into a flared shape -- thought they were ruined. I threaded them in to PVC female pipe thread adapters and dropped them into an old 30 cup coffee maker for an hour,then into cold water for a time.
  That worked pretty well,and now they will seal fine and are still soft.
 
Now that more time has passed they are fitting even better. I agree that checking the band clamps will be a routine as they settle in once the bike is running.
  My original boots were so hard that I had to take them off by removing the metal intake tubes from the intake manifold. 

[lucky]

K and F models carb insulators

 Z1 Enterprise
 set of four carb insulators for CB750 K and F models: $76.21

 Honda Parts Direct
 $76.88 for set of 4 insulators A and B 

 $40.98 CB750 A model sets for Grumberg from Honda Parts Direct if they are still available.

I have been using my Wintergreen and xylene mixture for 2 years on 4 bikes and all are running and idling fine with no vacuum or air leaks. $10 worth of ingredients saved me over $300. Why throw something away if you can make it work again?

Thanks SWAN for giving us DIRECT links and not making us go on a easter egg hunt! LOL...lol..lol

[lucky]

The 77-78 carb boots are shorter.