Compression and leakdown tests: info needed

[FzrAtx]

I have been having some oil burning issues lately and was wondering if any of you wrenches could do a quick how to write up on a compression test and a leakdown test. I understand basically how to do it, but was wondering about the fzr specifics like how to kill the ingnition for compression or how to get the cylinders to TDC for the leakdown test.

[reelrazor]

I have been having some oil burning issues lately and was wondering if any of you wrenches could do a quick how to write up on a compression test and a leakdown test. I understand basically how to do it, but was wondering about the fzr specifics like how to kill the ingnition for compression or how to get the cylinders to TDC for the leakdown test.

Okay.

Compression test:

Remove tank cover....remove airbox. Once the airbox is out of the way, you are staring at the ignition coils. Run the engine and get it warm(you can do this before or after removing airbox-but if you do it before, try to remove the airbox and get to teh comp test quickly) Unplug them (two wire harness plug on each coil...one will have a red and an orange wire...the other will have a red and a grey wire). Ignition now disabled.

Use a screw in compression tester-the 'hold-in' type are quite literally useless for anything but lawnmower engines. I think it's a 10mm thread in the plug holes..maybe 12mm?

Hold the throttle open and use a paperclip or something else(without obstructing the carb throat) to hold that cylinder's carburetor slide open.

Crank for a couple of seconds or 'til gauge needle stops rising. OEM spec is 171psi. watch the gauge needle as you crank....a quick rise to peak usually means valve seal is good...even if a low peak indicates poor compression (i.e. rings bad)

Check all four. You could do a 'dry' and a 'wet' test-retesting each cylinder after adding a bit of oil down the spark plug hole..a large rise between dry and wet confirms ring seal is a culprit.

WRITE EACH READING DOWN-ON PAPER!

Leakdown test- Which, if I have ANY choice, I would use before a compression test.... :


A) acquire a good leakdown tester and a stable compressed air supply (compressor-'charge cans' won't have the volume to accurately test four cylinders)of roughly 100psi.

B) calibrate(zero needle at peak-0% leak position) leakdown tester to air supply

C) Remove stator cover (left side of engine-mostly round)

D) align 'T' mark on flywheel with crankcase split at front(always rotate counter clockwise)-you now have a 50/50 chance at having cyl.#1 at TDC. (one of the timing 'bumps' will be right near where the pickup coils sits when the stator cover is installed-basically at the 1:30 o'clock position)

E) screw tester into #1 hole and apply air while watching the flywheel. If you are at TDC It will MOST LIKELY turn under air pressure....if not, cut air supply and turn 360°. If it turns forward(counter clock) turn back to step 'D' stopping just before marks come into alignment. If it turns backward (clockwise) Re-align marks going just past aligned. The point is to catch it exactly at TDC so that the engine won't turn under air pressure-this is tricky but can ALWAYS be done-experience helps.

F) take reading while engine is under pressure-stalled at TDC...note whether leak is from exhaust, intake, or crankcase(remove oil fill cap, and listen to crank breather tube)..... write it down

G) Turn crank 360° and install tester in cyl. #4 and test it as above...write it down

H) Turn crank 180°(will be on the other timing 'bump') and test cyl. #3...write it down

I) Turn crank 360° and test cyl. #2...write it down

J) post test results here.

In both tests deviations of any decent percentage between cylinders is cause for further examination.

[FzrAtx]

Thanks for such a good write up reelrazor!!! You answered every question I had about the procedure. I will get right on it and post the test results here.
Many Thanks again

[reelrazor]

Thanks for such a good write up reelrazor!!! You answered every question I had about the procedure. I will get right on it and post the test results here.
Many Thanks again

No problem

Threw it into the Wiki

[yamaha_george]

Thanks for such a good write up reelrazor!!! You answered every question I had about the procedure. I will get right on it and post the test results here.
Many Thanks again

No problem

Threw it into the Wiki

RR,
you threw it but God knows where it landed, to clarify the write up some pictures would help the "aged"

[reelrazor]

RR,
you threw it but God knows where it landed, to clarify the write up some pictures would help the "aged"

yeah. I went and re-did it just now.
I'll have my own dedicated garage soon, so it'll be easier to work and take pics. I wrenched flat rate-for 'production' for so long that it is actually kinda irritating to get slowed down.....

[yamaha_george]

RR,
you threw it but God knows where it landed, to clarify the write up some pictures would help the "aged"

yeah. I went and re-did it just now.
I'll have my own dedicated garage soon, so it'll be easier to work and take pics. I wrenched flat rate-for 'production' for so long that it is actually kinda irritating to get slowed down.....

RR,
I must admit that I have to really force my self to break & take pictures but although it takes longer "on the job" it saves time not having to answer the same questions over & over.

Please put a link here to find the WIKI bit as I cannot see it mind you this piece of junk I am using does not help LoL

[reelrazor]

Please put a link here to find the WIKI bit as I cannot see it mind you this piece of junk I am using does not help LoL

It's in the 'general bike maintenance' section...I just did some editing, cleaned up my other 'How To's' as well.

[yamaha_george]

Please put a link here to find the WIKI bit as I cannot see it mind you this piece of junk I am using does not help LoL

It's in the 'general bike maintenance' section...I just did some editing, cleaned up my other 'How To's' as well.

RR,
Yup,
found it but had to sort out the WIKI Syntax as it was scrambled a bit, I'm of the grid again so bye.