Is carb spray a sure way to find an intake leak?

[DClark]

I sprayed some carb cleaner on the boots between my engine and the carbs. After about 10 secs, the idle started to go up. Did the rpms go up because the carb cleaner got sucked in through a leak in the intake boots, or is it possible that as the carb cleaner dripped on the engine, the heat vaporized it and it got sucked in through the intake, making the rpms go up?

[Black_peter]

The carb cleaner will most likely drop the idle. Sure way to tell is spray some into the air filter.

[kevin2502000]

The carb cleaner will most likely drop the idle. Sure way to tell is spray some into the air filter.

Really? I have always had the opposite effect of it revving up. Do the aircleaner thing and get back to us on this.

[unit44justin]

The carb cleaner will most likely drop the idle. Sure way to tell is spray some into the air filter.

correct it should work the same way as a car intake, the idle should drop as if it were going to stall out and then it will pick back up to normal idle after the carb cleaner has evaporated

[loudnlow7484]

Carb cleaner will make the revs drop. You can even kill it if you get crazy. BRAKE cleaner on the other hand works just like starting fluid......

[kevin2502000]

Carb cleaner will make the revs drop. You can even kill it if you get crazy. BRAKE cleaner on the other hand works just like starting fluid......

Maybe that is what I am thinking of, I know SOMETHING I used to use on the old 2 cycle dirtbikes would rev them up when there was an intake leak. But then again that was years ago and senility hadn't set in yet.

[Ilovemyvtx]

I don't know what ya'll are smoking but my carb cleaner makes the bike rev up.

[kevin2502000]

I don't know what ya'll are smoking but my carb cleaner makes the bike rev up.

Pass that fatty my way............

[jetmerritt]

Maybe the new "safe" carb clean that doesn't burn will snuff an engine, BUT I always used to use Wynn's Carb clean at work and if a car wouldn't start and the fuel pump was suspected, we would use CARB clean as a fuel replacement and a little squirt would start the engine right up.

Brake cleaner on the other hand, no idea.

In theory, if you were tracing a vacuum leak and found one, the carb clean I used to use would cause the engine to rev up when introduced into the lean air mixture as it was a fuel source. If you added the "safe" non flammable carb clean to any intake air I think the revs would go down.

My thoughts anyway, I used to run engines off carb clean all the time.

[loudnlow7484]

I've never used Wynn's, but Gumout, and both Advance and Autozone's house brands are non-flammable (and they take forever to evaporate as well). If you have a carb cleaner that contains alcohol then it will burn. I didn't think any parts-store available brands would be flammable, though, because that would be asking for a lawsuit in the event of a backfire. It's been quite a while that parts-store carb cleaner has been non-flammable. I remember very clearly around 2004ish cleaning the carb on my 73 Eldorado, and having to keep it revving while I sprayed.

Brake cleaner, on the other hand, is always flammable. I've used the "safe" kind, and the unsafe kind, out of aerosols and bought in gallon jugs, and all of them will work as starting fluid in a pinch. IIRC, so will body solvent.

Maybe if we listed specific brands of carb cleaner this would clear it up a little bit?

[kevin2502000]

Well the carb cleaner I used to use like 15 years ago would melt plastic screwdrivers, I'm gonna go out on a limb and say that was the "good" kind.

[Astro4x4]

Well the carb cleaner I used to use like 15 years ago would melt plastic screwdrivers, I'm gonna go out on a limb and say that was the "good" kind.

Ahh yes, good ole MEK.

[DClark]

It took two weeks to get a new Suzuki brand air filter so I am a bit afraid to spray some carb cleaner in it.
Bike runs great cold. When warm, it has a dead spot at about 3500 rpms, a bit of a stutter. Also the idle tends to hang too, as if it were lean.
If I turn the screws up and make the mixture richer, the stutter seems to get worse. If I turn the screws in and make it leaner, the stutter diminishes but the idle hangs a lot more.I sprayed carb cleaner over the boots, no change in idle. Sprayed carb cleaner over boots when bike was hot, idle went up.
My theory- bike runs good at start because all is well with the world. As bike
gets warm, a leak develops somewhere in the boots. Perhaps one or more of the O rings is fatigued and as it gets warm, it starts to leak. What'd ya all think? Bike is a '91 Katana 1100 with 21K miles.

[loudnlow7484]

Ahh yes, good ole MEK.

MEK like Methyl Ethyl Ketone? (MEKP is the catalyst for polyester resin)

That s**t will kill you!

[Black_peter]

I remember very clearly around 2004ish cleaning the carb on my 73 Eldorado, and having to keep it revving while I sprayed.

Way before that, like 1997 doing my wife's Mercury..
Had to keep is revving with one hand and spray with the other.