Hey guys , i just picked up a compression tester at sears, i'd like to go ahead and check out my psi on the banshee. What is the absolute correct way to do this? First timer here [img]i/expressions/face-icon-small-wink.gif[/img]

 

You need to start her up and get it up to operating temp. Then pull out both spark plugs and screw in the tester. Hold the throdle wide open and kick the engine over and see what the highest reading is. Repete for the other side.

 

See now here's the trick. Ive been reading many different aspects of this. Some say to check the compression COLD. Others say to warm it up, but so far both have said to leave one spark plug in. They also say to leave both spark plugs attached and put them on the head. Now, maybe everyones different, just wondering what the most correct way is.

 

Do the test cold. Thats the way it is explained in the service manuals. Tolerances change when the engine is warmed up.

Pull both plugs....no need to keep them connected and touching the head. (if I'm understanding your post right)

Hold the throttle wide open (fuel off)..and kick until you achive the highest reading...repeat for the other side.

As a general rule of thumb....a banshee typically likes to have the compression at or around 120psi or higher in each cylinder. I have seen them run at much less. But I like to freshen things up with readings below 110...or even sonner if your tedious.

 

You dont need the plugs attached to the wires and touching the head, just keep that SWITCH off.
(so no spark is produced in the first place)

 

Personally, I always check my compression cold.

If you ever have a motor problem and can't get it to start, then you can do a compression check on a cold motor and see where you are at. If you always check the compression cold, then you always have a number to use as a reference point. This way, it helps to determine if you have a piston/ring problem, and in some cases, rule out piston/ring problems.

This has helped me in the past with diagnosing engine problems.

 

Its best to do it with the engine warm so the pistons have expanded up to size and are sealing correctly.Kick the engine over with both spark plugs removed and the ignition shut off.Kick until you get the hightest reading (may take 3 or 4 kicks).Hold the throttle wide open while you are kicking it over. The difference between hot and cold won't be that much so you can still use it for future reference if the engine won't start to warm it up to do the test.Usually if you are having a compression related problem so that the engine won't run(like a holed piston or broken rings) it will be very obvious on the gauge.

 

Another thing is make sure the guage your using is good. Cheap gauges can vary greatly. I thought what I had was 2 good ones that read about 20lb different from each other and was about 20lb less than I thought it should be. After spending the money for a good new one the reading was about what I thought it should be. A motor must make 80lb of compression to start regardless of it being a 2 or 4 stroke.

 

Bubba hit the nail on the head.
Cheap compression testers will not give accurate readings, BUT they can be used for reference. In other words, reference the compression of a Banshee that you KNOW to have a good top end and compare it to yours, OR check yours when it has a fresh top-end and use THAT as the baseline.

Generally 115 on up is good for the Banshee from what I've read.
We had a cheap compression tester that read 35 lbs less than the motor builders. Our friends read 10 lbs less than ours, so, there IS great variation amongst them unless you get an expensive one like a Snap-On which run close to 200 bucks.[img]i/expressions/face-icon-small-wink.gif[/img]

 

Also, make sure you screw the sparkplug in tight.
Some people take the washer off the sparkplug and put it on the tester to make sure there is a good solid seal.

Kick it over with the motor cold is usually how its done. No certain amt of kicks, just keep kicking as fast and hard as you can with the throttle wide open, till the compression reading stops rising.

And as mentioned, make sure the switch is in the OFF position.[img]i/expressions/face-icon-small-smile.gif[/img][img]i/expressions/face-icon-small-wink.gif[/img]