leakdown tester

[LagerDrinker]

This is one tool you hear alot of in motorcycle forums but few get into how it works for regular peeps.
What does it do? measure how much leakage from combustion chamber through valves and rings.
Whats needed? aircompressor with minimum 120psi.
where to start? refer to shop manual and get test cylinder to top dead center of compression stroke (piston all the way up and both valves closed) this must be done to all cylinders which will be tested.
Connect air hose to manifold, guage closest to air supply is your test pressure, guage next to outlet is leak %. the knob under manifold sets your test pressure. Turn knob til guage on left reads 100 psi, the guage on right should also read 100 psi.



Once guages are set disconnect air hose. Take hose in pic and screw into spark plug hole. The other end of the hose connects to the right side of the manifold. (for safety purposes wear protective glasses) reconnect air supply.


The guage on left should still read 100psi(adjust if needed) the other guage will read less. whatever that number less than 100 is you cylinder leakage. If its reading 95 psi then you have 5% leakage.

[LB]

wow, you're one real fart smeller....ummm.... I mean smart feller...LOL Seriously this is some great info!!!

[KingHardcor]

This is something I've been meaning to do for a while but never really knew how to do it. Thanks for the info. Is this similar to doing a compression test?

[sh8kr]

The leakdown test is more of a trouble shooting tool to find out if thw valves or rings are damaged. Example: Air coming thru the Carb problem Intake valve, Air coming from the exhaust problem Exhaust valve etc. most would agree that 10% is the most difference you want to see.

[LagerDrinker]

leakdown and compression are same but different...

1)Compression tester takes the whole stroke of the piston to give findings.

2)Leakdown tester is looking for obvious failures such as broken rings or burnt valves/seats at TDC.

one tests the condition of a engine(compression) and the other tests for broken stuff(leak down).

Like sh8kr sayed, leakdown is for diagnosis.

You really shouldnt need to do either test without a good reason such as bike doesnt run or you have high miles and considering rebuild. If you are faced with either scenario i hope this answered all your Q's about it.

[KingHardcor]

It did help. I have 70K on my engine. She still runs great but I notice a small loss of power from several thousand miles ago. Which is to be expected but I've been thinking of a top-end rebuild/freshening up. Be good to know the condition of the engine before I go ahead with anything. Maybe leave it for another year or so.

Thanks, guys.

[Berserker]

How To Make An Engine Cylinder Leak Down Tester
Haven't tried it, but its on my list of things to do. Link is on making a tester.

[KingHardcor]

I forgot all about that site.

[Berserker]

Originally Posted by KingHardcor

. Maybe leave it for another year or so.

Thanks, guys.

Winter is coming, go with 95",cams, and head work You got 70k now,I said when I hit 100k would open it up and take a look, maybe stroke it, its only money.

[KingHardcor]

I have all of that now. I know I can tear it down and do it myself(after all, if you can do it then anyone can! HA!) but I'm a little intimadated. Plus, I'm afraid I'll just keep going into it and end up rebuilding the whole thing and spending a ton of $.

Actually, I'm planning on saving cash now and next winter doing the whole engine. All the way down to and including the bearings(Timpken crank). Just to make it brand new or better.

I'm sure she'll hold until then.

I kind of want to know know though the condition of the top end. Probably do that leak down test this winter.