I have a pressure/vacuum setup I made to test two strokes. It is basically just two plates. One bolts onto the exhaust port with a rubber gasket and has a threaded hole to which I installed a 0 to 10 lb. pressure gauge. The other mounts to the intake manifold in place of the carburetor and has a metal automotive valve stem installed in it. I use a small hand held pump for basketballs and such to pump the engine up to 5 psi. (No more than that.) If the engine won't hold pressure, I use soapy water to find the leak.
It is also good to check them under vacuum as well. For this I use a hand operated vacuum pump. I remove the valve core from the valve stem fitting and connect that to the vacuum pump with rubber hose. Pump it down and see if it holds. If it holds pressure but not vacuum, suspect the crankshaft seal.
The pressure gauge can be sourced at a hardware store; they are used to pressure test home gas systems. The bolt in style metal valve stem can be found at the auto store. The hand operated vacuum pump can be found quite cheap at Harbor Freight, the little hand pump for basketballs I found in the sporting goods section of Walmart, and I make the block off plates out of 1/4" x 1 1/2 or 2" aluminum strap material. Doesn't take long to make nor cost much, and when you test your engine with it, you KNOW your engine is air tight, as it should be. (Must be!)
AV8TOR
Last edited by av8tor1977; 02-02-2018 at 01:56 PM.