cb350f power loss when warm

stowaway117

New Member
Hello gents, more 350f problems:
Took a ride last weekend and 20 miles from home I experienced extreme power loss going up hill. Found a safe spot, shut her off and did the standard checklist; coil leads, plug wires, fuel flow. All were good and after 15 minutes of kicking rocks and my helmet around I gave her a romp and she fired up no problem, banging on all 4 once again. Until about two miles later what felt like two cilynders cut out again. Let her cool off for ten and bam, back on all four. Once I limped her home I got to diagnosing and here we go:
When cold all 4 cylinders have fuel and spark , no problem. Once she warmed up 2 and three cut out. No spark. Both coils are brand new and after poking around with a test light and reading some threads on here about the Dyna ignition I narrowed it down to a bad Dyna. Picked up a new one at 4 into 1 in San francisco as mine was years passed their extremely short warranty period. While I was bleeding money I went ahead and ordered two new coils from DCC. Not dynas, just the $30 5ohm ones they sell. Slapped it all together today and feeling like a heroin addict needing a fix i geared up and hot the road. She fired third kick and ran like new. Until 2 miles down the road when 2 and 3 cut out. This time though, full spark in all 4. So I'm lost . my next move is pull the carbs and check for flow or a loose jet but I wanted to see if anyone has another idea... Thanks guys.
 
It'd be a coincidence if both 2 & 3 carbs were gummed up at the same time, but not impossible. Seems more likely it could be ignition. That being said, it'd be easy to check the jets and float bowls to see if there's anything floating around. Are you sure it's both 2 & 3 not firing?

I had a jet clog on my 350F on the freeway and I didn't really realize it -- maybe happened as I was accelerating or something -- but it didn't have the pull past 65 and it started to get hot. This might be why it's cutting out when warmer, if it's overheating. I'd double check that it's both, rule out carb obstruction, then go to ignition. Would also check condition of the plugs, mixture, etc.
 
I'm definitely leaning more towards ignition, its not giving me the normal starving for fuel symptoms. Im positive its 2&3. Did the old meat thermometer in the heat wrap and 2&3 are colder than 1 and 4.
 
Check then double check the wiring going to the coil and pick-up for 2 and 3. A cracked wire might be the culprit as it can lose continuity when it gets hot.
 
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