I was looking in my service manual this AM to see if i could find the specs and procedure to check my compression....I can't see it anywhere in there...Any advice would be appreciated...How to do or where to look...
07 TC96 on a FLHTC.

 

Remove plugs,open throttle valve and crank the engine.The gauge will peak after a few revolutions.
A leakdown test may be req'd if you get low readings.This will tell you if the valves or rings are leaking.

 

You will need a good compression tester; Sears has several that will work well and don't cost an arm and leg.

http://www.sears.com/shc/s/search=co...e=CAT_REC_PRED

Just make sure that whatever you get has the 12mm adapater.

Remove both spark plugs and connect the tester to either cylinder; make sure the connnections are tight. No need for wrenches; the connections are all fitted with o-rings so you just need to get them good and finger tight; no leaks.

If the bike is EFI, hold the throttle wide open and spin the engine; watch the gauge and after about 5-6 strokes, it will stop increasing. Record the reading and repeat on the next cylinder. If the bike is carbureted (CV) the slide is vacuum operated and you can open throttle plate but the slide will not raise without engine vacuum and will restrict the air flow to the cylinder. So, I just pull the carb off; you can leave cables connected, just pull it from the intake and push it to the side to allow unobstructed air flow to the intake so the cylinder can fill. Repeat the above process.

The two cylinders should be within 10psi of each other; a larger variance is an indication that rings are worn, valves are worn or guide seals are failing. If one cyliner reads much lower than another, squirt some motor oil into the cylnder, spin is a bit and take another reading. If the second reading (with oil) shows higher than the first, rings are going. If the reading is the same, valves or guide seals are going. Check the service manual for what the compression should be.

There is a second test to isolate the problem; a leakdown test which will require another tester.

Google search on compression and leakdown test and you will find more information.

 

Thanks Guys...I surely appreciate the input...doesn't sound too complicated.

 

8 complete cranks on the starter, battery charger in place, throttle plate wide open.
Scott

 

I am getting a tester this weekend. looks like a simple procedure enough...The reason i am doing this is recently my bike seems to have a little less ooomph! I was riding on the interstate... about 75-80 mph on cruise control and going up a slight incline it dropped down to 70mph then back up to set speed on level road...
My bike is still under extended warranty but the dealer is backed up for 2 weeks with work...
I'm gonna ride it for the summer and when it get a bit cooler i will drop it off...I am curious about the compression though , it has 72000 miles.

 

Scott's post notes "battery charger in place"; good point and one I missed in my previous post. A less than fully charged battery will produce low compression readings.

At 72K miles, it is very likely that the top end needs freshening up but warranty does not cover normal wear and tear.

 

Well i did the test myself and it was apparently good... dry test at 175 psi on both front and rear... One of the Mechanics at my dealer said it may be the cruise control or the throttle cables??? My plugs were a bit dirty but looked pretty good...I am happy it's not a compression problem but baffled at what is the issue.