Rookie wrench and a head gasket

souljur412 wrote: What is a leak down test n how do ya do it....

A leakdown test injects air pressure through the spark plug hole to pressurize the combustion chamber.

There's a test kit that includes a fitting to inject air into the spark plug holes, along with pressure gauges to determine rate of compression loss, etc.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates loss of compression past head gasket (perhaps due to a blown head gasket).

Poor man's leak down test --

Can perform a poor man's leak down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).

Good Fortune!

I did a research(internet) on the leak down test. From what I've learned it's kinda useless on a motorcycle.it was designed for aircraft engines and should be used for such... this bike sat for a long time not sure how long... Please if your gonna post on this thread post real talk...stretched bolts(c'mon),,, crazy ass tests,,, I wanted to do this myself now I'm not sure...I just want my bike to run good for some summer ridin,,, is that too much to ask?

A Leak Down Test is for the Internal Combustion Engine. Doesn't matter if its a Aircraft Engine or something else. There are even tests for the Crankcase of a Two Cycle Motor, where a low 5psi of pressure is used.
Take the advice of are Forum Members and Check out your Motor thoroughly before tearing it apart. It will most likely steer you in a correct direction for repair. Then when you finish your bike will be performing at its designed power level, and be reliable.

souljur412 wrote: I did a research(internet) on the leak down test. From what I've learned it's kinda useless on a motorcycle.it was designed for aircraft engines and should be used for such... this bike sat for a long time not sure how long... Please if your gonna post on this thread post real talk...stretched bolts(c'mon),,, crazy ass tests,,, I wanted to do this myself now I'm not sure...I just want my bike to run good for some summer ridin,,, is that too much to ask?

Wow! If you consider a leak down test a "crazy ass test" that is "kinda useless on a motorcycle" then I respectfully suggest you take your bike to a qualified motorcycle mechanic because you really have zero familiarity with motorcycle engines and will very likely cause more damage once you pull the engine apart. Assuming your cylinder head gasket is leaking the leak down test will verify that problem, but more important is the FACT that it will also reveal other possibly compression leaks such as valves or piston rings BEFORE you pull the head off the bike. I believe you severely underestimate the quality and value of the advice some of the folks have given. There was a bit of chatter about bolts stretching, but the folks who responded to your posting in a serious manner know what they are talking about, so do yourself a favor and don't dismiss their advice so lightly. Ed

I have had numerous engines backfire really bad and never once blown a head gasket from it. Do a complete diagnostic including a leakdown test and go from there. Do not just start tearing into the engine based on limited info. That gets really expensive and time consuming.

souljur412 wrote: I did a research(internet) on the leak down test. From what I've learned it's kinda useless on a motorcycle.it was designed for aircraft engines and should be used for such... this bike sat for a long time not sure how long... Please if your gonna post on this thread post real talk...stretched bolts(c'mon),,, crazy ass tests,,, I wanted to do this myself now I'm not sure...I just want my bike to run good for some summer ridin,,, is that too much to ask?

Well that useless test can tell you if the rings are sealing and if the valves are sealing without pulling the motor apart.
It would really suck to go to all the trouble of pulling it all apart and just slapping a head gasket on there only to find out that now that the head is all sealed up and doing its job the rings or the bores are worn out allowing all the compression to blow by them and out the crankcase vent.
Personally I never do just a head gasket for just that reason,In my experiance anyway if a motor is tired/beat enough to need a head gasket chances are its atleast due for a set of rings.
And while I have gone to all the work of having a head off I spend a little time on a valve job and a set of valve guide seals atleast while its apart and check the guides for play.
Thats just how I do things,I dont know much about airplanes other than jumping out of them when I was young and dumb but I know just a little more than some about air cooled 4cyl bike motors.
You can probably get a leak down tester for free from neighborhood parts store,just give them a deposit which you get back when you return it.

Hey bro's,,, I wasn't dismissing any advice, sorry if it seemed as though I was. As i said I am a novice wrench, light mechanical is all I've ever done on bike's so being a little cautious about what to do is just plain smart in my book. I greatly appreciate the experience that is being shared with me here. The leak down test i looked up on internet so,,,,,it can be unreliable. I think I may just take her into the shop as this is gonna be my summer ride, maybe I'll go with the wiseco 810 kit seein as I'm goin this far, I'd like my GPZ750 to be all it can,,,thankz