XR compression test

mtngoat

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#1
I'm picking up a compression guage from White Bros. next week. Anyone offer any tips, tricks or traps to check compression on XR4s?

Thanks.
 

Mark C.

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#2
Warm the motor up to proper operating temp. then kill it, put compression adaptor into sparkplug hole, hold throttle open, and kick the beast untill the little needle won't go anymore. Repeat a few times to correct.
 
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#3
One problem is that you won't get a "true reading" due to the cam mounted auto-decomp. But as a reference figure it will be fine.
 
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#4
Kick the bike thru more slowly than you would to start it. The decompressor won't open. It's a fine line between fast enough to "pump" the air, and too fast - sometimes it works and sometimes it doesn't!

Make sure you have the throttle wide open, otherwise the engine doesn't have a good air source and you'll get a low reading.