Working on a '73 CB200 for a friend. This was a running, riding bike until about a month ago. She called me just as I got home from a local bike night and said she broke down. The bike kept cutting off on her. She was able to limp it home and I went a few days later to get the bike.
Got it to my house and checked the plugs and they were good....not fouled. She had JUST installed two new NGK D8EA plugs in an attempt to get it running again. I pulled the sediment bowl on the petcock and the float bowl on the LH carb. Both had clean gas and no trash in them. I checked fuel flow through the petcock and the float valve. Put it all back together and put the bike on the charger (battery was working...turning the bike over, anyway). The next day, I noticed the fuel level was a little low and that the petcock was new, so I put it on reserve and the bike started. The trip meter showed 71 miles. "Ah-ha! Aftermarket petcock and high reserve pipe! She was just out of gas!".
Told her to order new points, condenser, and spark plug caps and we'd install them when she came to get the bike. Did that last night, minus the points because the old ones look brand new, and tried to start the bike.
No Go.
It just cranks and cranks and cranks with the occasional cough like it WANTS to start, but it won't.
*We changed the condenser, since a bad condenser can sometimes fail when hot, so I wanted to eliminate that.
*Checked the plugs again. Gave them a quick clean but they didn't really need it.
*Trimmed back spark plug wires and installed new NGK caps.
*Checked the sediment bowl and fuel flow through petcock again.
*Charged battery overnight, but it turned the bike over fine for 15-20 minutes while we tried last night.
*Removed one of the air cleaners. It doesn't look bad and is OEM. When cranking with the air cleaner off, I can see fuel moving through the carb. No change when trying to start with that one filter off.
*Dressed the points. We're getting spark at the points and at both plugs.
*Did the finger over the spark plug hole test and it has compression.
At this point, I'm stumped. We seem to have fuel, air, compression and spark. It just won't run. Tried kicking it. Tried bump starting it.
My next move is to check valve adjustment, timing and actually setting the points rather than just cleaning them. I can't imagine that the timing or valve adjustments are off that bad. I mean, I have compression, and when I got the bike running it ran great. No noises or hesitations or flat spots.
What the heck do I check next?