Topic: 1980 CB 650c troubleshooting.

[PAKMAN]

Hello, first time posting but have read many very helpful threads over the years. So awhile back I was riding and the bike began to backfire like mad and died and would not start or even fire. Had to park it for quite awhile cause I was moving out of state for work, last year started digging into it and found that the keeper nut for the advancer came loose and it must have spun out of timing. Followed the manual and reset the timing, changed the oil and the plugs and it would start with some help from some starting fluid but did not want to idle and had to keep the RPMs up or it would die. Fast forward to know it unfortunately had to sit again and I moved out of state again. Decided to start digging into it now that I have my garage set up. Drained the old fuel and built a new fuel line with a new inline fuel filter. Pulled the carbs and cleaned them well. Still did not want to run, realized cylinder #3 didn’t seem to be firing and found a fouled plug so I replaced it and now it seems to be firing. Double checked the timing and still does not want to run or idle and I have a fuel times gotten backfires into the air filters. Has a fresh battery and I’ve checked spark. Seems to do slightly better with the choke on so I’m guessing it’s running too lean but the carbs seem to be doing just fine and can’t find any of the floats sticking etc. I did have to swap out the petcock on the fuel tank as the original was leaking and I’m curious if that could be restricting fuel flow and it’s not getting enough to the carbs? Any thoughts would be appreciated.

[Don R]

 The fuel we get nowadays doesn't store well and likely has plugged your pilot jets. Also, you mentioned filters, does it have pod filters, and if so did it run good before putting them on? 
 I personally have had trouble with inline filters gelling up. They look good but won't pass fuel.

[scottly]

Since the problem originally started from the advancer coming loose, I would go back and have another look there. The protrusion on the advancer should be a certain distance from the metal bar on the pulse generators, and if the loose advancer made contact with the generators the adjustment might have shifted.  (Sorry, I don't recall the spec off the top of my head) Also, there is a 3mm pin on the back of the advancer that fits into a hole in the crankshaft; make sure that's intact.

[newday777]

Welcome aboard the forum PAKMAN.
As Don said, I suspect that your idle circuits are not clean.
Did you remove the slow speed(pilot) jets and the high speed jets and emulsion tubes? How did you clean the excellerator pump circuit? Without doing so, it won't start easy
What process did you use to clean your carbs?

http://forums.sohc4.net/index.php?topic=143617.0

[PAKMAN]

So I double checked the flow out of the fuel line and it’s flowing just fine with the new fuel filter. Double checked the advancer at TDC on cylinders 1-4 on the compression stroke and the mark is lined up correctly. Cleaning the carbs I just followed my Clymer Honda manual for the cleaning process. I don’t have single pods but I do have K&N 2 to 1 air filters and it’s ran great on the before the issues. Will probably pull the carbs again tomorrow and look to see if maybe I missed anything.

[newday777]

Saying that you followed the Clymer manual doesn't say how you did it.
Did you just squirt sray carb cleaner or did you take the carbs all apart and deep soak them or did you use an ultrasonic cleaner???

Did you read through the link I posted?

[scottly]

Double checked the advancer at TDC on cylinders 1-4 on the compression stroke and the mark is lined up correctly.

The F mark on the advancer is where the timing is set, not the T mark. Are you checking the timing dynamically using a strobe light? Did you check the timing on cylinders 2-3?