Check intake boots for leaks, without carbs on?

First... I know this is a total shot-in-the-dark question. I figured still worth asking, though, 'cause you never know.

I should've tested for vacuum leaks before I took everything apart. Buuuut.. too late for that now.

I've got the carbs off the bike, and I'm just curious if there's any inside tricks for checking the intake boots for issues (the rubber still seems pliable on what I've got). ... I mean, aside from squinting and flashlights?

I'm just hoping there's a middle ground between "order new ones and be done with it" or "find one has a vacuum leak after it's all back together." The first is more expensive. The second is more tedious.

If I have to, I'll lean towards just replacing them all, but I figured I'd ask first before draining the checking acount!

 

There is a repair that can be done to seal cracks in the boots. You can use your finger to smear black RTV on the manifolds, and then stretch sections of bicycle inner tube that have been cut to the length of the manifolds to cover them up. For your sake, I hope someone comes along to better describe the process, my language skills are lacking right now.

 

I would go ahead and do the old-school fix while you have easy access. The only thing that it won't cure is if there is a vacuum leak at the head flange.
Using an inner tube is optional, and mainly for looks.

First you will thoroughly clean and degrease the boots ( I like to scuff them a bit with a wire brush first), cleaning as far into any cracks as you can get.
Once they are dry, use gloves and work black oil resistant RTV into the cracks, and then add a layer over the entire boot.
Finish up by putting on a new pair of gloves, and use a wetted finger to smooth the RTV so it looks pretty.

I can't recall what size bicycle inertube you would use, but that goes on instead of the final smoothing of the RTV. You have to cut the tube so it's the same length as the boot, and punch a hole for the vacuum port to fit into.

Whichever method you choose to finish the repair with, it can be considered a permanant repair and should last quite a number of years.

 

I confirmed that the seals between the airbox and carb boots were leaking by sealing temporarily with strips of tape and noticing
an improvement in idle. For a permanent fix I would think that whatever I caulk that joint with should remain flexable in case the
boots have to be removed in the future. Would black RTV be he best ?

 

Black RTV would be fine, and would peel off fairly easily. You could try one of the non-hardening sealants, but that might be a bit messy if you need to take the carbs off again.

 

Thanks, the boot mounting holes in the airbox are a little ragged. A bead of black rtv would seal nicely as long as it peels off
to enable boot removal.

 

By the way, boiling the carb boots softens the rubber enough so that with a little soapy water sprayed on the airbox flanges they pop into place effortlessly.

 

Treating them with a bit of oil of wintergreen makes them like new.
http://v4musclebike.com/forums/showthread.php?t=13477

 

Boiling and soapy water makes the boots easy to install but they get stiff again when they cool off
I used a dry heat gun to soften them for removal

 

a leak there isn't a vacuum leak, sealing that joint is a little over the top, i think. the amount of unfilered air that could get in there is insignificant.
inner tubes are not UV resistant. if you've made big rubber bands out of a old inner tube you know this, they last about six months, then start cracking.
if there are any big cracks in the carb to engine boots, open the crack and get some super glue it it then wrap the boot with this
https://www.homedepot.com/p/3M-Scot...ess-Rubber-Spicing-Tape-41717-BX-10/205523418
your good for twenty years

 

Definitely significant for me. I'm in the hottest part of this country. 300 days of sunshine to UV cook everything.

(Summer's are fun. It's like riding your bike down into that heat gun JoeJr2 is using on his carb boots.)

 

that tape is pretty much forever, the outdoor splices on your electric service are wrapped with it

 

Yes living in Santa Fe during a drought is no picnic either. My swamp cooler motor burned out last Sunday and I spent two days getting the parts
and fixing it. Up on the roof in the sun when it's 101 is no fun.

 

Yes , I agree that stuff is way better than regular electrical tape. Thanks for suggesting it. The electricians had it on my projects. I don't know why I didn't
think of it.

 

Twice as thick, is probably part of the reason?

I just did this last weekend... RTV’d the boots and wrapped them with the splicing tape. Other than a couple xacto blade cuts to wrap the nooks and crannies at the back and not cover bolts ‘n such, it was easy-peasy.

So we can start the clock now and see how long it lasts. (I’ll report back in a few years! Haha)

 

I can confirm that the inner tube fix doesn't last long, about 9 months for
Also, wintergreen softens the boots perfectly but again this is a temporary repair, they harden up again pretty soon