AT LOW IDLE SPEED ITS SPITTING

check spark plugs check fuel line and filter for blockage

plugs to cold

Check for air leaks on manifold. I will assume to mods to engine or ECU map. Spitting can be caused by lean mixture.

Put a spike air filter on my 06 honda shadow spirit 750cc and now it spits and sputters won't go past 35 with out spitting and sputtering

Recheck your firing order for basics. If this is in good, a compression test may be necessary. Which enigine do you have?

There are a few things you can look at here:

1. The EGR Valve or Idle Air Control Valve
2. Check for misfires in your cylinders, possibly bad coil
3. Check your fuel pump and fuel filter

Those are the most common issues with fords spitting and sputtering

Enrich the fuel mixture by going to a bigger low speed idle jet.

It sounds like it is running too rich (too much fuel). First, make sure the air filter is clean and that there are no intake leaks between the carburetor and the engine. Also, try a new spark plug (they can go bad without warning). Then, with the engine at normal operating temperature and idling, adjust the idle mixture screw to attain the highest idle speed. After this, set the idle to the correct speed using the idle speed adjustment screw.
Test ride. If it still spits and sputters at half to full throttle, then you will need to get a smaller main jet - or go to a less restrictive air filter, such as one by K&N.
Finally, I am not sure what prompted you to put a carburetor kit in, but if the bike had been sitting for any lenght of time (more than 6 months) make sure the carb isn't plugged up.

If it is old enough to have points then I would check them and make shure they are clean and gapped at .020. if that is noth the problem then it sounds like a fuel issue. Either a weak pump or a dirty carb.