compression test

bcliburn · Jan 27, 2016

I am Goin to attempt to do a compression test on my 135 with 3 cyl gas, anyone have the stops for this process do I take all spark plugs out etc. And what should my compression be thank you

blue water massey · Jan 27, 2016

remove all plugs
and remove a wire from the coil to prevent shocks
all cyl should be close in readings to each other
if I remember correctly no more than 20% differance from highest to lowest
crank motor over 4 or 5 compression strokes you'll hear them and take your reading
not sure what the compression should be but have seen motor run as low as 50 and as high as 160
most likely more in the 90 - 120 range
if you have a low cyl after testing put a couple oz of oil down nto the low cyl and retest
if you get an noticable increase in compression it means the rings are weak
no real increase probably a bad valve or a hole in a piston
if 2 side by side cyl's are low it usally means bad head casket or cracked head

Charles in Aus. · Jan 27, 2016

To add to the excellent advice , make sure the battery is fully charged and disconnect the air cleaner to allow an unimpeded intake.

bcliburn · Jan 27, 2016

Ok so I just got done, I pulled plug disconnected dist from coil, cranked motor until gauge stopped climbing 4 or 5 cranks and on each cyl had 150 did each one 3 times just to be sure. Drained my dang battery to haha but all were equal to one another so I guess that's good

blue water massey · Jan 27, 2016

150 psi in each cyl is great
sounds like it's a good runner
due a tune up n run her

bcliburn · Jan 27, 2016

Thank you for all the help

compression test

bcliburn

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blue water massey

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Charles in Aus.

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bcliburn

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blue water massey

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bcliburn

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