In regards to compression, this is not true. As things wear the engine will become weaker and more difficult to start, especially when hot. Gas mileage will suffer snd you will be down on power. Sometimes noticeably and other times not so much. I would check the compression to ensure you're not working with a tired engine. Honestly its best to know what you're working with. You honestly could have excellent compression.

How old are the ignition components? Weak ignition components can cause hard starting. Does the fuel pump that you put on produce more fuel pressure than the original pump? If so, you'll need an external fuel pressure regulator to dull the fuel pressure down. You can always install a fuel pressure gauge in line in the feed line going to the car to verify you have good solid fuel pressure when cranking the engine.

If the carb has never been rebuilt, I don't think it's a bad thing to rebuild it. Replace the fuel filter when you do if it's an older filter. Having good compression, good ignition components, and a known good fuel system should give you reliable engine starting hot or cold.

When running, can you verify that you have zero vacuum leaks? A vacuum leak can also cause hard starting. Something to consider.

 

Since no one has a solid idea I recomend getting new plugs / cables.
My dad's 89 toyota truck was running poorly , it never gave him issue starting up but would crank a bit longer than normal and would bog and gave him poor power on first gear. At first i suspected he blew his head gaskets considering the poor truck has hauled some ungodly loads for what it is . We replaced the cables which looked "good" with some OEM Spec Denso ( don't use denso on our cars , use NGK) and the truck instantly started up like a modern car but still had hessitation at WOT which was fixed after replacing the plugs . Granted his plugs had no gap left , but if your plugs and cables are old this will give you a hard time. A set of plugs and cables will set you back like 30$ .
As others said above , if you don't know your plug and cables history replace them, a bad cable will cause a load of issues .

 

Those are all good ideas. But I did direct fire, new plug wires, and plugs last year. Once I get it running, I can shut it off, and restart w/o a problem.

My bet is the lack of choke.

 

Was the choke removed when it started with 3 pumps?

 

yes, choke has never been installed

 

Then why would the lack of a choke be the problem now?
I ran my last 7 for years without the choke , started with 2 or 3 pumps.

Instead of pumping the pedal, spray or pour a little fuel down the carb throat the before you try to start it.
If it fires right up, then one would assume it's not getting enough fuel when you pump the pedal.

 

ya, you read my mind. In cold North East winters, that's what it would take.

 

Ran a high end bike shop for years. Had a wise mechanic who when digging into diagnostics would mutter ‘to get to what it is, eliminate what it isnt.’

Assume choke butterfly is still in place, and by having no choke you mean that there is no cable or it’s not hooked up? Is it possible to hold the butterfly manually closed (zip tie? Finger? Screwdriver?) then try to start? That would eliminate or prove choke as the issue.

And whilst staring down the barrels, eliminate / prove the accelerator pump. Have someone blip the accelerator and see if the two jets at the very top of the main barrels squirt. See yellow circle in pic.

 

The choke butterfly valve is closed. Started right up after sitting 1 day when I poured some HEET (methanol) down the carburetor.