excessively rich mixture 84 750 interceptor

ok so part three of getting this bike running, cleaned the carbs, new fuel pump relay, i finally get the bike running and its running ok but my fuel economy is that of a truck(80 miles to 1 tank) and the exhaust reaks of unburned gas.... im also trying to sync the carbs right now but i cant seem to get past the thermostat on the right side to get to the vacuum port on cylinder 3, any tricks on doing this would be great, ive tried unbolting the thermostat from the motor mount and removing that triangle bracket but i cant move the thermostat enough to get by it

 

ok one last thing, i just cross referenced part numbers on the fuel pump relay i replaced, the pn is 36100-MB3-701 for the 750, i bought a relay for v65 magna thinking they would be the same that part number is 36100-MB1-701 could that be causing the pump to push too much fuel into the carbs?

 

Nope, it's not the pump because it works (if you want to call it that) just the same no matter what relay you are using. Plus your floats will stop the flow when the bowls are full. On that note....

I'd you probably have a needle/seat that is not sealing or a bad float. Maybe it's just a float that is not adjusted properly (could have been bent when you cleaned them) or is sticking. I'd check the plugs to see which cylinder(s) is running rich, that will help you zero in on which carb is having the trouble.

 

Or...somebody put an el crappo jet kit in at at some time...or drilled out the jets to clean the carbs (nasty trick). Unless you know the history of the bike, there's a lot of possibilities "on the table".

If your bike has a vacuum petcock (can't remember for sure), you may want to vacuum test it. On occasion they can fail and dump raw gas into the cylinder that feeds them vacuum right through the hose. So...if that particular cylinder is the rich one, make sure to check that before you tear the carbs out again.

If the problem is with needle, seat or float...as JD suggests, they usually run worst at idle, when fuel requirements are least and that extra gas is overwhelming.

I've synched carbs on that model before, but not for quite awhile and I don't remember any particular difficulty accessing any vacuum ports...so I don't know what to tell you there.

 

Just happened to think of something else...check your choke cable...and inspect the plunger on each separate carb to make sure they are all in synch and completely closed when your enrichener is off.

 

To get at that last vacuum port, use the small space between the thermostat housing, and the engine mount plate (the black thing with three bolts in it). You will notice the thermostat housing is actually made so a screwdriver and adapter tube will squeeze (and I mean squeeze) by.

As for running rich... nobody mentioned the air filter yet.