Performing cam change....perform compression test?
Thread Starter
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Tourer
Joined: Apr 2010
Posts: 401
Likes: 2
From: Odenton, MD
Performing cam change....perform compression test?
I posted this question in the general section without much feedback..thought I would try here.
I purchased the cams, pushrods and lifters from Fuel Moto. I read all the threads and watched all the videos......
I was reading the lifter install directions from Fuel Moto and it says to run a compression check with the throttle open after adjusting the pushrods. This is the first time running across this test when reading about a cam change. Is this necessary or is it for those doing the big builds or more complex engine work?
I purchased the cams, pushrods and lifters from Fuel Moto. I read all the threads and watched all the videos......
I was reading the lifter install directions from Fuel Moto and it says to run a compression check with the throttle open after adjusting the pushrods. This is the first time running across this test when reading about a cam change. Is this necessary or is it for those doing the big builds or more complex engine work?
Road Captain
Joined: Aug 2010
Posts: 702
Likes: 16
From: Zebulon, NC
I never did. I was real comfortable on setting my rods.
If you email or call Fuelmoto, they can probably give you the lowdown on why that is in their instructions. probably to make sure the valves are sealed up top....
If you email or call Fuelmoto, they can probably give you the lowdown on why that is in their instructions. probably to make sure the valves are sealed up top....
the way I do a comp test is to turn the engine over with the comp gauge installed. if the pushrods are not set right then you would put the valve into the top of the piston; if you set the pushrods as most instructions say, and let them bleed down before starting to the next set, everthing should be good. or they may be taking about compression test after setting to make sure they are all closed during cycling...but you would probably need a test before you started the process to determine if the numbers are the same....
Stellar HDF Member
Joined: Aug 2007
Posts: 2,052
Likes: 342
From: Virginia Beach
Follow the directions, just make sure the lifters are both down as far as they can go on the camshaft when you adjust your pushrods. Watch the S&S video
it is incredibly easy. Let the lifters bleed down after adjusting each push rod. May take 10-15 minutes each. I just did it. No problems at all...
Thread Starter
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Tourer
Joined: Apr 2010
Posts: 401
Likes: 2
From: Odenton, MD
OK, so if I do decide you run a compression test are these the correct steps? (note: I have my tank currently off)
1) connect battery
2) spark plugs already removed
3) gas tank and fuel lines connected
4) disconnect spark plug wires from the ignition coil
5) connect gauge in one spark plug hole
6) open throttle and hold down start button until gauge stops moving
7) record pressure and repeat on other cylinder
Is this correct? Anything missing?
Thanks.
1) connect battery
2) spark plugs already removed
3) gas tank and fuel lines connected
4) disconnect spark plug wires from the ignition coil
5) connect gauge in one spark plug hole
6) open throttle and hold down start button until gauge stops moving
7) record pressure and repeat on other cylinder
Is this correct? Anything missing?
Thanks.
Road Master
Joined: Dec 2008
Posts: 872
Likes: 20
From: Niagara Falls Canada
decompression releases
dont forget to unplug your decompression releases while doing the testing or u will get a lower number. did mine plugged in and unplugged just to verify that they are both working. think it dropped about 30 lbs while plugged in if i recall the numbers. checking the compression after a cam job is a pretty good idea, lets u verify cam timing is correct, both cylinders should be fairly close, also gives u a number to start with in case u have a problem later, u know where u started after the rebuild.
If u have throttle by wire u will have to force the throttle plate open with a screw driver, since it will only open a bit while trying to start on its own from iac setting until it fires up. it will give a lower reading if u dont force it open.
If u have throttle by wire u will have to force the throttle plate open with a screw driver, since it will only open a bit while trying to start on its own from iac setting until it fires up. it will give a lower reading if u dont force it open.
Last edited by 2009blackpearle; Apr 26, 2013 at 09:06 PM.
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Cruiser
Joined: Jul 2009
Posts: 137
Likes: 0
From: Las Vegas, NV
OK, so if I do decide you run a compression test are these the correct steps? (note: I have my tank currently off)
1) connect battery
2) spark plugs already removed
3) gas tank and fuel lines connected
4) disconnect spark plug wires from the ignition coil
5) connect gauge in one spark plug hole
6) open throttle and hold down start button until gauge stops moving
7) record pressure and repeat on other cylinder
Is this correct? Anything missing?
Thanks.
1) connect battery
2) spark plugs already removed
3) gas tank and fuel lines connected
4) disconnect spark plug wires from the ignition coil
5) connect gauge in one spark plug hole
6) open throttle and hold down start button until gauge stops moving
7) record pressure and repeat on other cylinder
Is this correct? Anything missing?
Thanks.
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Cruiser
Joined: Jul 2009
Posts: 137
Likes: 0
From: Las Vegas, NV
OK, so if I do decide you run a compression test are these the correct steps? (note: I have my tank currently off)
1) connect battery
2) spark plugs already removed
3) gas tank and fuel lines connected
4) disconnect spark plug wires from the ignition coil
5) connect gauge in one spark plug hole
6) open throttle and hold down start button until gauge stops moving
7) record pressure and repeat on other cylinder
Is this correct? Anything missing?
Thanks.
1) connect battery
2) spark plugs already removed
3) gas tank and fuel lines connected
4) disconnect spark plug wires from the ignition coil
5) connect gauge in one spark plug hole
6) open throttle and hold down start button until gauge stops moving
7) record pressure and repeat on other cylinder
Is this correct? Anything missing?
Thanks.
Thread Starter
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Tourer
Joined: Apr 2010
Posts: 401
Likes: 2
From: Odenton, MD
Wouldn't unplugging the wires from the coil make this unnecessary?