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Post by olescoot on Nov 17, 2013 16:42:51 GMT -5
Bought tester from Harbor tools. Will that work?
I have read that one needs to ground plug and crank with full throttle. Is it ok to just use kick start without plug grounded? What is best proceedure?
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Post by alleyoop on Nov 17, 2013 16:49:07 GMT -5
You are checking for compression not SPARK. So take the plug out screw the compression adapter in like you would the spark plug, then hold the throttle wide open and crank it over. If you have electric start use that, it is better, constant turning of the crank. You will see the reading on the gauge go up and finally not climb and that will be the highest compression your motor is putting out.
Alleyoop
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New Rider
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Post by olescoot on Nov 18, 2013 18:51:37 GMT -5
Thanks alley. Saw a video and they said you could damage the ignition if you didn't connect and ground the plug. Also said to turn off the fuel.
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Post by alleyoop on Nov 18, 2013 21:07:15 GMT -5
ROOKIES, all it will do is spark inside the boot cap and yes a little bit of fuel will be in there but nothing to do any damage, Many motors get flooded even cars.
Alleyoop
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Post by Mainely Scooters on Nov 21, 2013 23:43:03 GMT -5
Have to be careful with some of the cheapie compression testers. We have 4 different brands in the shop and they never read close to each other. (One read 250psi when another read 70, both BRAND NEW). What's most important is the change in compression from a known point. Don't trust the exact number shown, but compare it against another engine or another source you can get an idea.
Greg
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Post by alleyoop on Nov 22, 2013 0:55:03 GMT -5
Just go to an auto parts store and get one, as a matter of fact some will even have a compressor to test them for you.
But here is the thing you will know if your compression is really low just by turning the motor over with your hand. If it has descent compression you will have to use a little muscle to rotate it past the compression stroke.
If it has low compression you will be able to rotate it very easy. You can also use the old hotrod trick of putting a finger in the plug hole or if you have big thumbs just cover the hole where the plug goes in. Then open and hold the throttle wide open and crank it, if it has descent compression it will blow your finger off the hole. If you just feel some pressure then you know you have a problem. It could be the rings or a valve is not sealing. You can then adjust your valves and try again. If still weak pressure pour a tablespoon of oil down the plug hole and re-check, if this time you get more pressure you then know its your rings.
Alleyoop
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..BAD TO THE BONE..
