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Compression test

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dreaming
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Joined: Sun Jun 05, 2011 8:17 pm
Location: Kearney, Nebraska

Compression test

Post by dreaming » Thu Jun 09, 2011 4:15 pm

Well, just ordered Mr. Silvers book, and a carb kit. Going through the steps of start up and checked compression on both cylinders of my ca72. With the kick start it reads an ever 72 on both sides. I'm really having trouble finding the good compression window for this bike. Any idea?

Also, are the ca72 and ca77 air filters interchangeable? I can find one for a 77, but not mine.

Any help would be great. Thanks!

Goodysnap
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Joined: Mon Oct 06, 2008 7:25 pm
Location: Lansing , Michigan

Post by Goodysnap » Thu Jun 09, 2011 9:26 pm

Should be over 100 for proper combustion. Higher the better say 150 or maybe more on a fresh rebuild. I can tell you my 305 runs good and only has around 125 or so.

Before you get too worried, make sure you have the throttle opened full while testing. I've found with the slides closed it gives false low readings due to not enough air being drawn into the cylinders. Also test with both plugs removed.

Not sure about the air filters- not real familar with the CA's.
64' CB77
65' CB160

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brewsky
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Location: Princeton, WV

Post by brewsky » Fri Jun 10, 2011 4:35 am

CA77 and CA72 air filters are the same.

Goody is right...dont forget to hold throttle wide open, no choke and preferably engine warm.

How many times did you kick?

FWIW, the Honda Service Manual lists 120 PSI for C72's
66 dream, 78 cb750k, 02fz1, 09 wing

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