New fuel pump... carb cleaned but not rebuilt...
Good gas ... won't fire..
Tries harder when throttled..
But won't fire..
At my wits end.... help!!!

 

Do you have spark? Fuel flow to cylinder? Fresh gas? What things have you already tried?

 

Has spark....seems like gas not getting there to ignite...bowl has gas in it...

 

You can remove the plug and pour a little bit of gas in the cylinder. Replace the plug and it should start if only momentarily. That would tell you if you have a fuel flow issue. If it has sat for a while, did you remove the jets and clean them out also? The pilot is susceptible to clogging with old gas varnish or even dirt/gunk from the tank or float bowl. I would probably pull that pilot and check it as the next step.

 

Has spark....seems like gas not getting there to ignite...bowl has gas in it...

 

Added gas .. did start.....pilot removal???

 

Has spark....seems like gas not getting there to ignite...bowl has gas in it...

 

Did remove and cleaned jets ...It ran... but realized
I had the fuel and vacuum lines reversed..started smoking..
Reversed lines and ran till smoke stopped...3 minutes or so..
Turned off ... Tried to star again 20 min later .. not starting...
Clean jets again???? Or am I up a creek??

 

I am not sure what you mean by vacuum line? Apparently this machine has a fuel pump, could this be what you hooked up backwards?

 

Fuel system diagram.

Suzuki ATV Parts 1987 LT300E FUEL TANK Diagram

Diagrams of your bike:

1987 Suzuki QuadRunner (LT300E) OEM Parts, Babbitts Suzuki Parts House

Carb specific. Remove bowl and there are your jets.

1987 Suzuki QuadRunner (LT300E) CARBURETOR | Babbitts Suzuki Parts House