checking for air leaks

[apache18]

Can someone tell me, when I am checking a motor for air leaks. Do I have the piston up top or at the bottom, while blowing on the fuel line? Thanks Joe

 

[Jeremy]

I would think top dead center. not sure, good ?

 

[apache18]

Thanks for the help. Joe

 

[Crash]

how is this test performed

Hey guys, how exactly do you do this air leak test?:dunno:

 

[Jeremy]

crash.... https://www.hpisavageforum.com/forums/showthread.php?t=1511

 

[HopIt]

Basically what your tryin to do is pressurise the inside of the whole engine. The best way to do this is, firstly block off the exhaust port and carb intake. You can you use your fingers to do this or I found it easier to use plastic dust caps, the ones I have are made by Ultimate Racing. They come in different sizes to cover all the various holes to keep out crud. Then once the engine is sealed up, connect a piece of fuel tubing to the fuel inlet on the carb and blow down it. It's a bit nicer if it's a clean bit of tube, it also wants to be about 12" long so you can see what's going on better. Now while you are blowing down the tube ( you have to blow pretty hard ) you need to apply some very soapy water to the suspect areas. The best way to do that is using a hand pump spray bottle. You will see any leaks when the solution bubbles up. If you want to check your head is sealed, it's better to have the piston at BDC so the air can get past it. Don't be surprised if you get a bit of air coming from the front bearing, because the dust seals on a bearing aren't air tight ! But depending on how much use the bearing has had will determine the amount of air coming out.

 

[apache18]

Thanks for the reply. That is what I was looking for. Thanks again.Joe

 

[Crash]

sweet, thank you guys.........

 

[HopIt]

Glad to be helping someone for a change, it's usualy me asking all the questions !! :bigsmilie: