83 750 Twin not starting.

OK here is the latest update on my trials and tribulations. My bike is not even trying to start. I believe that it is not getting any fuel through the carbs. I tried this evening to make it flood since that would rule out the no fuel theory. But I could not make it do that. I know fuel is getting into the carbs, and I know it is good gas. I also know that the carbs are clean and not clogged. My question is... Is it possible the diaphrams are so old they are not opening correctly? I lost my shop manual so I need to pick the collective brains of the forum members to get this bike back on the road where it belongs.
Thanks in advance for any and all help.

How are you going to make the carburetors flood? I doubt you can. To check to see if the carbs have fuel, either remove a bowl or open a a drain screw. I assume the bike is turning over when you push the starter button with the bike in neutral and the kill switch in the RUN position? If it turns over and the bike doesn't start:

1. check bowls for gas by removing a bowl OR opening drain screw. If no gas, then we can investigate why the bowls have no gas if there IS gas:

2. remove spark plug. Put the plug into the spark plug cap and hold it next to the engine and turn the engine over. Do you see a spark jump from the plug to engine? The plug needs to be a bit less than 1/8" away from the engine. If there is a spark and you had gas, then we will have to explore reasons why the bike doesn't start (separate line of troubleshooting starting with compression, etc) and if there is no spark, we will look at the ignition.

wiredgeorge wrote:

How are you going to make the carburetors flood? I doubt you can. To check to see if the carbs have fuel, either remove a bowl or open a a drain screw. I assume the bike is turning over when you push the starter button with the bike in neutral and the kill switch in the RUN position? If it turns over and the bike doesn't start:

1. check bowls for gas by removing a bowl OR opening drain screw. If no gas, then we can investigate why the bowls have no gas if there IS gas:

2. remove spark plug. Put the plug into the spark plug cap and hold it next to the engine and turn the engine over. Do you see a spark jump from the plug to engine? The plug needs to be a bit less than 1/8" away from the engine. If there is a spark and you had gas, then we will have to explore reasons why the bike doesn't start (separate line of troubleshooting starting with compression, etc) and if there is no spark, we will look at the ignition.

1) Check
2) Check.
Carbs are cleaned and no trash in fuel. Fuel is fresh. New coil, plug wires and plugs. The spark is a white to bright blue, plugs gapped to the correct specs. I have done nothing to the timing, but it is concievable something could have happend on its own (weird things happen around me a lot :silly: ).

It's easy to flood the motor, just block off the intake side of both carbs with your fore arm and crank the motor over, and I guarantee the motor will be flooded (if the carbs are getting fuel of course).

I have done it many times to establish that fuel was getting through.

Although if it should pick that moment to backfire through the carbs, then a loss of arm hair will ensue

Well I replaced the diaphrams and am proud to report that after a 50 mike shakedown run this afternoon she is running stong and starting easier than ever before.
Thanks ya'll.