How does one find an air leak?

spray carburator cleaner around the mating surfaces (carb to intake, intake to engine) and the motor will either rev up or sputter, depending on how much it sucks in.

don't spray it into the carb throat itself, and try to keep it away from the air filter.

also, carb cleaner can eat lousy paint, so go easy on it.
 
Any luck on that air leak? I know alot of times on bikes like these the carb will slip a little out of the boot and cause problems.. good luck!!




:-||
 
I use WD40. Less harsh. Less effective, though, too.

If you do use carb cleaner, just be careful to distinguish the difference between an air leak and carb cleaner getting sucked into the intake through normal carburetor activity.
 
The best thing to spray to find a air leak is starting fluid!! (The engine will very noticeably rev up where the air leak is.) ;)
 
You can also use the presure smoke test. depending on where the leak is pump the smoke into the engine with all holes blocked and look for the smoke. I use this to check exhaust leaks on cars. It just depends where your leak is. Hope this helps
 
hurricane said:
oh you stole what I was going to say .. haha so much more entertainment value when using starter fluid vs cleaning fluidlaff
Click to expand...

This is also a way to introduce very highly flammable liquids (hydrolized either is explosive) into not only the combustion chamber but also into the crankcase of the engine and a method that can produce some very unwanted results that can cause serious damage to the engine as well as potentially dangerous to the person performing the test.

The prefeered method is utilizing inert gasses (air) and pressurizing the engine while it is not running as I outlined in the previous link.

Be that as it may do what you think proper just don't whine when you have an engine come apart in your face.
 
Actually I prefer WD40 as a starting fluid for 2 smokes. Far as things I have used to find a air leak I have used Carb spray, [unlit] propane , brake clean [was the worst], and yes Starter fluid.
As a practiced Mechanic in a shop not always well stocked I getter dun. As to weather a guy has enough common sense around anything well some folks should not even own a bike..
 
Starting fluid is some volatile stuff. If a guy uses it on a rotary engine that's a no no. it will bow it up. Loading up a crank case is a bad thing with this stuff just a tiny snort will do. I think if used properly checking for a air leak in a ventilated area is ok in moderation. I think using the stuff that way dun correctly it will work perfect. Yes starting fluid is the most dangerous

Not every body can pressurize their engine. I have used a smoke machine before and loved it. Suggesting these Ideas I think are perhaps all ok if'n folks are warned.

The Carb spray is my favorite for something I am the most familiar with. However it will eat your paint if not careful Some one blatantly spraying starting fluid into their motor is absolutely wrong I am picturing a guy making silly rev noises with their motor.

we just gotta use what we have with some sense is all. Shrug
 
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MarkSumpter said:
Randiman this is the procedure I have used for many years to find airleaks in 2 cycles. It is a briefly detailed description but if you need help let me know:

http://motorbicycling.com/f52/basics-port-polish-port-matching-16646-6.html#post237700
Click to expand...

mark...what do you think of this as an alternative for a cheap leak down system..a shrade valve could also be used for those who don't have a compressor but a simple bike pump....


at any auto parts store there are fittings that substitute for a spark plug, (used w/ compressed air to pump up the cylinder when changing valve seals)

then you screw on a air chuck/ or shrade valve with a petcock between the chuck and fitting then useing the correct size hose and hose clamps,use short bolts on the open ends w/clamps, seal off the intake manifold, as well as the exhaust nipple on your muffler

then you only have to put maybe a pound or two of air charge on the engine, get a spray bottle with some dish soap and water and spray away....you should get bubbles where theres a leak....you'd probly have to cycle the engine to allow the crankcase to get pressurized.....but you wouldn't be introducing any potential "KA-BOOM'S"......

it wouldnt cost more than $10 bucks for the whole set up...and its safe for the novice...and with the shrade valve and a bike pump anyone could do it.....what do you think?
 
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Star Products , 71319 Small Schrader Valve Hose Assembly w/ Quick Coupler Plug -Ford

Google

Google

Then we need to carve away some very thick sheet metal to make our cover plates for the exhaust and intake. Have not got to a schrader valve yet! That could be coupled to a hand pump? I am not feeling 10 dollars here. Unless of course a guy has scrap materials lying around. Got any 10 dollar links it would help the lets keep us all safe ploy/cause. I am hip with that! Really I am..

I realize the over all ploy here to try to say what is dangerous and what not!

Mark Sumpter's way to check for air leaks is the most accurate way to check for air leaks bar none with out a doubt. So I ask you this em: Jim Charlie Gene? I know its Jim this time. Ch should be here shortly with his cap locks on. Snork. Are you going to make a simple leak check kit in your machine shop now and sell it to us through a vinder perhaps? That is a great Idea!


It is a really cool thing a guy could very easily make in a machine shop v it from nominal scraps out of another bigger job! If I were you I would totally do it!!
 
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Goat Herder said:
Star Products , 71319 Small Schrader Valve Hose Assembly w/ Quick Coupler Plug -Ford

Google

Google

Then we need to carve away some very thick sheet metal to make our cover plates for the exhaust and intake. Have not got to a schrader valve yet! That could be coupled to a hand pump? I am not feeling 10 dollars here. Unless of course a guy has scrap materials lying around. Got any 10 dollar links it would help the lets keep us all safe ploy/cause. I am hip with that! Really I am..

I realize the over all ploy here to try to say what is dangerous and what not!

Mark Sumpter's way to check for air leaks is the most accurate way to check for air leaks bar none with out a doubt. So I ask you this em: Jim Charlie Gene? I know its Jim this time. Ch should be here shortly with his cap locks on. Snork. Are you going to make a simple leak check kit in your machine shop now and sell it to us through a vinder perhaps? That is a great Idea!


It is a really cool thing a guy could very easily make in a machine shop v it from nominal scraps out of another bigger job! If I were you I would totally do it!!
Click to expand...

sorry your not feelin $10....but im soo happy your "HIP"....i am indeed Charlie...not Jim nor am i Gene....

Marks rig is without a doubt "Top Flight"....but not everyone has a radiator pressure test kit...they are a lil exspensive......and not everyone has a compressor.....

since you like to "goggle"...the spark plug fitting by KD tools is available for $5.75....i did not say you needed a whip hose

as for the shut off valve one listing for 1/4 " was for $5 and change as well but im sure it could be found for less....

the shrade valve could be used from a truck tire innner tube stem as they are steel (and a dumpster find at the local tire repair shop) it could be used in a compression fitting as could a common rubber valve stem.....sorry you couldn't figure that out........shame on me!

as too thick plates?....my suggestion was the use of hoses, clamps, and short bolts to seal the hose ends...with clamps as well.....

as far as pressure to the case....you'd only need very little to be above ambient...which is something like 28.5 inches mercury or water on a manometer.....you knew that right?

and the other thing is this could very well be done while the engine was mounted within the frame...and not "benched"


so other then that.....AND MY USE OF THE "CAP'S KEY"...(so horrible on my part).....im aware that there are 2 people whom i will not further engage in conversation on this site..........
 
I am totally aware of how to make a cheap inexpensive pressure kit how ever newbe's are not. The old schrader valve from a tire shop is a awesome Idea no that had not occurred to me at the moment but would have if I had to have constructed one.. I have to this date not needed to make a pressure kit tho. If I needed to check for leaks in that manner I would perhaps just use a pressure regulator and my ubber Snap On brand cool Mechanics compression test kit witch already came with this stuff and it's own regulator. Tell the guy's I said high!;) Peace Merry Christmas The Goat..:)
 
mr.charlie said:
mark...what do you think of this as an alternative for a cheap leak down system..a shrade valve could also be used for those who don't have a compressor but a simple bike pump....


at any auto parts store there are fittings that substitute for a spark plug, (used w/ compressed air to pump up the cylinder when changing valve seals)

then you screw on a air chuck/ or shrade valve with a petcock between the chuck and fitting then useing the correct size hose and hose clamps,use short bolts on the open ends w/clamps, seal off the intake manifold, as well as the exhaust nipple on your muffler

then you only have to put maybe a pound or two of air charge on the engine, get a spray bottle with some dish soap and water and spray away....you should get bubbles where theres a leak....you'd probly have to cycle the engine to allow the crankcase to get pressurized.....but you wouldn't be introducing any potential "KA-BOOM'S"......

it wouldnt cost more than $10 bucks for the whole set up...and its safe for the novice...and with the shrade valve and a bike pump anyone could do it.....what do you think?
Click to expand...
mr.charlie said:
sorry your not feelin $10....but im soo happy your "HIP"....i am indeed Charlie...not Jim nor am i Gene....

Marks rig is without a doubt "Top Flight"....but not everyone has a radiator pressure test kit...they are a lil exspensive......and not everyone has a compressor.....

since you like to "goggle"...the spark plug fitting by KD tools is available for $5.75....i did not say you needed a whip hose

as for the shut off valve one listing for 1/4 " was for $5 and change as well but im sure it could be found for less....

the shrade valve could be used from a truck tire innner tube stem as they are steel (and a dumpster find at the local tire repair shop) it could be used in a compression fitting as could a common rubber valve stem.....sorry you couldn't figure that out........shame on me!

as too thick plates?....my suggestion was the use of hoses, clamps, and short bolts to seal the hose ends...with clamps as well.....

as far as pressure to the case....you'd only need very little to be above ambient...which is something like 28.5 inches mercury or water on a manometer.....you knew that right?

and the other thing is this could very well be done while the engine was mounted within the frame...and not "benched"


so other then that.....AND MY USE OF THE "CAP'S KEY"...(so horrible on my part).....im aware that there are 2 people whom i will not further engage in conversation on this site..........
Click to expand...
mr.charlie said:
your just way to hip for me
Click to expand...



http://www.youtube.com/watch?v=LB5YkmjalDg:D
 
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When I check ultralight engines for crank seal leaks, I used blocks of wood with strips of of rubber, clamped over the intake and exhaust ports with wood clamps ,dont matter if it leaks just a little.

For air pressure, I used a standard pancake compressor, with regulator set to no more than 5 lbs, and used soapy water in a spray bottle to check the seals and gaskets for leaks.

Wayne Z
 
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