I suspect your start-up disappointment is spark related.
Here's a test you can do. Measure the voltage being delivered while the starter is engaged to the coils when the engine is cold (or when you normally encounter startup issues). Then compare that reading to when the bike normally starts quickly.
Here's why.
When the bike is cold or has sat for a while, engine cranking resistance is higher due to oil drain back and parts not having a lot of nice warm oil to lubricate sliding parts. Plus metal dimensions change with temperature, and this can also lead to increased friction.
Another factor is that batteries will self discharge over time. And, while the charging system rectifier minimizes battery drain, it does still provide a very small load load on the battery during non-operation add to battery drain. So after sitting for a while you battery may not be at full voltage potential. What with the huge starter motor draw and being partially depleted the voltage may dip into the marginal spark regime.
Speaking of spark, the spark plugs can get deposits on them to impede easy sparking. If you run at low throttle settings/ low engine temps, and especially with choke on, soot can build up near the electrodes. This provides an alternate electrical path for the spark energy and prevent mixture ignition. Ambient temps play a role in this, as well. D8 heat range plugs keep the combustion temps down when the engine is hot and running hard. These are actually too cold for occassional running in cold temps as the cooling fins overcool the engine in such conditions. A D7 plug would be better suited for a cold temp/infrequent running regime, where the engine doesn't get the plugs to a temperature that will self clean.
Another factor to impede spark could be that you have resistor plugs AND spark plug cap resistors. You should have one but not both of these. If there is an R in your spark plug number, then you should NOT have spark plug boot resistors, too.
Dirty plugs and low spark voltage will easily make an engine difficult to start when cold.
Finally, your choke mechanism does not have a mechanical link to the throttle that many other machines do have. Thus your choke will not increase your idle speed for you. In fact, the poor atomization that occurs when the engine is cold means that it will idle lower than when the engine is fully warmed up. You will have to manually open the throttle to keep the engine running, until the temps come up to operating temperature. This also occurs faster with the D7 heat range plug.
Cheers,
