Author Topic: 1974 CB350F - Very Low Compression in Cylinders 2 and 3 after rebuild.  (Read 754 times)

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Offline jethroswit

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Hey folks! Closing in (hopefully) on this 1974 350F rebuild I've been working on with a pal for a while. Tried to fire it up for the first time tonight and nothing doing. Got 4 sparks, timing is tight, however compression check shows that cylinders 1 and 4 are good (120 in both) and 2 and 3 are bad (70 in both). I did do a quick check of the valves and they weren't wildly off (going to fine tune them next time I'm in) - unless I got 2 and 3 reversed when I was setting clearances, but that would probably be pretty apparent like valves valves hitting pistons, right? I have some theories, but had to close up the garage for the night and thought I'd pose the question to the forum and let it marinate till I can get back in there and work on it again in a couple days.

Cheers everyone!
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Opposite of Pro
1970 CB 350
1976 CB 500f

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Offline gtmdriver

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My first thought, if the tappets are OK, would be that the head gasket is blowing between cylinders 2 & 3.