Fellow off roaders, I have a question.

I recently bought a 95 Yamaha PW50 for my son which is a two stroke dirt bike. As i began purchasing parts for the rebuild project i relized that i would need to do a leak down test, which is something i have never done. While reading how to go about it occurred to me that i should probably do one on my Warrior soon when i go thru my rebuild.
In the clymer manuals there are two different testers; one for the two stroke and one for the four.

My question is do you really need two different tester or can one be used to suit both?

 

The 4 stroke will just do the valves and ring seal. You pressurize the cylinder through the spark plug hole. I like 100 PSI because the math % is easy that way.

The two stroke is a low pressure system and you pressurize the engine case and cylinder with plugs in the exhaust and intake.

So no, the pressures and gauges are way different.

 

Thanks a lot for breakin that down for me. So now my next question, if i may, should i do the work and hope that all is good then take it to the a shop to be tested or put the money out and buy one for myself?

Just looking for an opinion really, thanks.

 

As mentioned above four strokes are pretty cut and dry on testing.Just pump up to 90-100 psi on the main gauge,the second gauge will show the amount of leakage,some air you can hear through the carb or exhaust if leakage is more than 10 percent! Different story on 2 strokes. You have to plug the exhaust,have an adapter to fit the intake with a low pressure tester and max pressure is 10psi (bicycle pump or equivalent only) or you will blow out the crank seals! Plus has to hold this pressure while spraying soapy water around the head,cylinder,seals,etc for leaks! Just weigh the cost of a shops price versus the testers price and your enthusiasm on doing the job ! OPT

 

I would not worry about it. I would do the work and see how it runs. If you do good work there is no reason to check it.
They make some really good case sealent now days. And if you use new crank seals and all of that there should really be no leaks.

 

This may be something of interest for you,

$17 Leak Tester (2-Stroke)

 

Awsome feedback. Thanks a lot. This has been a big help

 

No problem. Let us know how it works out for you.