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Discussion Starter · #1 · (Edited)
Hey guys! Been a productive year working on this 72 cb350 and have taken it from completely awful to totally “rideable”.

Putting a few hundred miles on it, riding, tweaking, riding, more tweaking.

I have got a fully functional refurbished electrical system and rebuild carbs.

Pardon the DIRTY air filters. Im being cheap until I can swing the $ for some replacements, probably murdering my carb rebuild...

You’ll see some not so nice stuff in the video below. The video shows the engine starting but i’ve developed a back firing issue.

Compression test shows 125 on L and 90 on the R. I did a seafoam soak when I first got the bike and it seemed to unstick whatever rings were stuck, and I got readings in the upper 140’s on both. But now im back around where it was when I first got it. Sure fire sign of needing a rebuild. Could this also be a valve issue as well? I just wanted some outside opinions on that before I delve into all of that again.

On the second video link I maybe suspect poor vacuum in R carb too. Sounds like the slide is popping up and down, possible tear in the diaphragm? I reused the originals and checked very closely for tears and holes. Is it very possible the mileage from this summer could have torn a hole in it?

There are some beautiful fall days ahead here in middle TN and I live just minutes from the Natchez Trace. I may try seafoam AND pb blaster this time over the next few days to see if I can resolve this until I barn it for the winter and get the top end rebuilt and address some other issues you might be able to point out in the video.....

Backfire:

Carb slide:

Thanks guys!

EDIT: I was thinking, could the poor vacuum in the R carb be a symptom of low compression in the corresponding cylinder?

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Discussion Starter · #2 ·
[SOLVED] Went through and adjusted cam chain tensioner, valves and timing and it turns out my timing was a bit more than a hair off. Here it is now after a little TLC. I did discover the top screw on my left cylinder point is stripped and not tensioning as it should. Anyone have a good spare one lying around they’d like to sell?

Also, soaking the hot cylinders in PB/SeaFoam for a few hours to see if it will loosen up, already idles, so it can only help I suppose, then going to change the oil to get the PB/Foam oil freshened up.

After Tune Up:


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