Cold starts require partial throttle

[roboto65]

I really think there is no difference between the 2 if any thing the  Ir plugs may have less resistance but not any seat of the pants difference no !!!!!

[Moja]

So can you tell ANY difference in the plugs???  Maybe swap em after riding a bit and keep a log..
Personally I think for stock ignitions, stock plugs are more than fine, any fancy plug is just fancy..

I don't have much butt-time invested so far, but I cannot feel a bit of difference.  Of course, we did commit the cardinal sin at the wrench session, and introduced multiple new variables into the equation - we did the plugs, shims, cleaned the low speed jets (which weren't really clogged to be fair), and just to further obfuscate things, inflated the tires

My observation thus far is that the bike does not have any discernible increase in power, but I would say the idle is a little smoother (and I can adjust it down a little lower without it stumbling) than before.  The "cold-bloodedness" that it displayed on Saturday after the job was long gone this AM - I fired it up with full choke (hovered at a little under 2000 RPMS) and backed it out of the driveway.  I then disengaged choke entirely, watched it drop to 800-900'ish, and I was on my way.  I gave it a fair amount of gas during take-off in preparation for any herky-jerky stumbles, but there were none.  And this may not be entirely relevant yet, since Tina (my gf, who probably has never gone past 1/3 throttle) put on the first 100 miles on the tank, but at 108, I still haven't switched to Reserve yet.  Undoubtedly some of that is coming from the tire inflation too.

I still have to give it throttle to start it though

[Greg Cothern]

Colin, sounds like she is running good!  To tell ya the truth have not seen many Magna's that would start without some throttle input just to get the fuel flowing.
Enjoy!

[Moja]

It's been a while (and this turned into a monster thread) but I think its worth updating as I learned some very valuable info during this process.

Although I never did anything else to the bike after the shim job (and stopped SeaFoam'ing) the problem just gradually went away.  The biggest improvement occurred just after the week of MOOTmag where we'd put probably 600+ miles on the bike.  So some combination of the seafoaming, new plugs, shims, and beating the snot out of the bike, and riding it regularly has got it running like new.  It doesn't matter if it sits for 4 or 5 days now (rare, but happens when I leave it behind and take the cage on a weekend trip or something) - it fires up instantly with no choke, and no throttle, and at worst will have a slight stumble in the first 1/4 mile or so on occasion.

The moral of the story:  MOOTmag will make your bike run better

Thanks again to all who chimed in!

CAB