Compression Test time!!!

[Infidel]

Hey Guys,

   Well, I'm off to pick up a compression tester & see for myself what is going on with my beloved bike. I have a pretty good idea how to do the test, but I'm absolutely open to any tips or suggestions. I'll let everyone know what I find.

   Thanks.

P.S.- I have been unable to post my avatar pic. I'm not really terribly internet savvy, and if there's a trick I'd love to hear it. Thanks, again!

[Arnie]

Fully charged battery
remove all spark plugs
attach compression tester
Fully open throttle
press starter button for at least 10 revs
write down your results
zero tester

repeat for each of the other cylinders

Now, put 5cc (about a teaspoon) of oil into the spark plug hole and re-test
write down your new number
repeat test with oil for each cylinder

Cheers,
Arnie

[JCainFJ]

 Skip the compression test and do a leak down test, it will be much more accurate.

[weymouth399]

Plus 1 on leak down test.

[andyb]

Different tests for learning different things.

[Mark Olson]

Check your valve clearance as well, fj's get tight as the miles rack up and need the valve shims replaced.

tight valves will = low compression.

[Arnie]

Skip the compression test and do a leak down test, it will be much more accurate.

He asked how to do a compression test.  Rather than just confusing the issue with 'other' things, why not tell him WHY he should do a leak down test, and then tell him HOW to do it.

Cheers,
Arnie

[JCainFJ]

Arnie said "He asked how to do a compression test."

No, Infidel said  "I have a pretty good idea how to do the test, but I'm absolutely open to any tips or suggestions."

With that in mind, I think that a leak down test is a very good tip and or suggestion when the opening statement is "Well, I'm off to pick up a compression tester & see for myself what is going on with my beloved bike."

A leak down test is more accurate then a compression test because it does not rely on the condition of the battery, the starter motor, the air filter, the amount of combustion chamber deposits, the amount of intake and or exhaust valve deposits, or the condition of the exhaust system. It is the preferred test for aircraft engines because it is the more accurate test.
Leakdown tests also provide more information about the condition of the engine when done. A hiss from the air box is a leaking intake valve. A hiss from the pipe is a leaking exhaust valve. A hiss from the oil fill is leaking rings or head gasket. A hiss on the outside of the engine at the head/head joint is a leaking gasket, and (not needed on the FJ) bubbles in the radiator indicate a leaking head gasket.

Have a look at this for a how to....

http://en.wikipedia.org/wiki/Leak-down_tester


As an additional tip, do a full tune-up before you start any of these tests. Correct valve clearances, a clean air filter, clean oil/filter, and a serviced exhaust system. I have a SuperTrapp exhaust on my FJ and my YZF, and cleaning the discs is very important. If the discs have an excessive build-up of carbon, the system will not flow properly. My dyno guy found 4 hp. by cleaning the discs on my YZF600.

[Ratchet_72]

You all ever notice how sensitive everyone gets on motorcycle forums the closer to spring it gets?
Relax everyone, the snows ALMOST gone.

...compression & leakdown for fucks sake...

[tqmx1]

You all ever notice how sensitive everyone gets on motorcycle forums the closer to spring it gets?
Relax everyone, the snows ALMOST gone.

...compression & leakdown for fucks sake...

Jay, Snow whats that?? 

[Scooterbob]

You all ever notice how sensitive everyone gets on motorcycle forums the closer to spring it gets?
Relax everyone, the snows ALMOST gone.

...compression & leakdown for fucks sake...

Jay, Snow whats that?? 

I second that!  What's snow?  You mean you guys (and gals) don't ride year round?   

[jamesearthdrum]

Infidel, Where are you at? I have a leakdown test kit you can borrow if you would like? Unless you just have to buy a new tool. I did 
Oh and for you guys that don't get snow......suck it!!

[Kopfjaeger]

looks at blue sky... highs of 37 deg C... dont start work till 2 30 pm.....hmmmmm.....

[Scooterbob]

Oh and for you guys that don't get snow......suck it!!

That's right. I'm "sucking" up all that warm sunshine at a sweet 75 degrees. 

[Pat Conlon]

Snow...In 2005 that is the reason I looked back east to buy a FJ1200.
I found her in Lafayette, Indiana with only 6500 miles on the odo. Must be due to Snow. $2,200, I scored, thank you Snow.
It was interesting to see how the ad for the bike stressed, that the bike was kept in a "heated" garage. Must be the Snow. Don't see the need for heating your garage out here. Snow. Where else are you gonna find a (then) 13 year old bike with 6500 miles on the clock?  Snow, gotta love it....
.... as long as I don't have to live in it.