New symptoms

[fadlan12]

Ok i have come to the conclusion that the # 4 cylinder is not firing or not hot enough, the exhaust pipe was warm to the touch compared to the other 3 being burning to the touch. I pulled out the plug and it was black tiped not sure if it was sparking at all. I carb cleaned and got some metal showing tested it and it was sparking good, did not tell any difference except when I plugged the boot back onto the plug the rpms shot up. when I pulled it back off it did not seem to make a difference in idle. But now with boot and sparkplug on its popping loudly out the exhaust. these are new plugs at least prior to carb rebuild so probably less than a few miles on them. Granted they have been in while I tinkered with the airflows and lean times so i guess they could foul out easy enough.

Popping means unburned fuel right? that should mean its getting fuel to the cylinder.

[zero9243]

Ok i have come to the conclusion that the # 4 cylinder is not firing or not hot enough, the exhaust pipe was warm to the touch compared to the other 3 being burning to the touch. I pulled out the plug and it was black tiped not sure if it was sparking at all. I carb cleaned and got some metal showing tested it and it was sparking good, did not tell any difference except when I plugged the boot back onto the plug the rpms shot up. when I pulled it back off it did not seem to make a difference in idle. But now with boot and sparkplug on its popping loudly out the exhaust. these are new plugs at least prior to carb rebuild so probably less than a few miles on them. Granted they have been in while I tinkered with the airflows and lean times so i guess they could foul out easy enough.

Popping means unburned fuel right? that should mean its getting fuel to the cylinder.

I assume popping means backfiring? It means there in unburned fuel catching fire in the exhaust, not in the cylinder. Also there is a air/fuel mixture screw on the carbs that are used for heat tuning. That one could be mad out of wack i suppose

[yamaha_george]

Ok i have come to the conclusion that the # 4 cylinder is not firing or not hot enough, the exhaust pipe was warm to the touch compared to the other 3 being burning to the touch. I pulled out the plug and it was black tiped not sure if it was sparking at all. I carb cleaned and got some metal showing tested it and it was sparking good, did not tell any difference except when I plugged the boot back onto the plug the rpms shot up. when I pulled it back off it did not seem to make a difference in idle. But now with boot and sparkplug on its popping loudly out the exhaust. these are new plugs at least prior to carb rebuild so probably less than a few miles on them. Granted they have been in while I tinkered with the airflows and lean times so i guess they could foul out easy enough.

Popping means unburned fuel right? that should mean its getting fuel to the cylinder.

I assume popping means backfiring? It means there in unburned fuel catching fire in the exhaust, not in the cylinder. Also there is a air/fuel mixture screw on the carbs that are used for heat tuning. That one could be mad out of wack i suppose

Hi,
Carb four is rich (ie well black ) should be dry but is probably wet looking. The unburned excess fuel is not being fired in the cylinder but is igniting in the pipe when the engine allows it to actually fire.

Put a NEW plug in the 4th cylinder and see if it improves if not then check the carb float settings on 4

[fadlan12]

I took it to the yamaha dealer and said good riddince no not really. They do have it to change fluids, brake pads and carb synch. and general maint. I am ready to get this sombitch working so i can go pimp it at the mailbox.