Pilot Jet

Looks to me like the jet is not the same size all the way through...
Guess I should have used the term "internal geometry" , not the general terms contour or shape!

   A not-uncommon issue on vintage bikes is voltage drop across various switches and harness connectors that  results in low voltage at coil primaries.  That results in weak spark.
 
   Battery voltage drops during cranking anyway, exacerbating the symptom of weak spark.  It's sometimes misdiagnosed as a carb issue.

   The coil relay bypass circuit mod was developed specifically for the reason of voltage drop.  It's very simple to install, and can be made PnP using appropriate connectors so an existing vintage harness need not be butchered.

  A quick & easy test of voltage at coil primaries during cranking would be informative.  Post the results; might save yourself needless carb work.

   Not gonna chime in on drilling jets; that's been well covered above.

Good Ridin'
slmjim & Z1BEBE

The video clearly mentions drilling the pilot jets to enlarge them, and eliminate lean running from stock.

To me, instead of drilling, just install the next size jet.  Simple and fast.  Not needed, mind you, but to each their own.

Regarding poor cold starting, that could be many things.  I always like to start out with surgically clean carbs, with fresh O-rings when ever starting a bike rehab project.  Could well be the choke passages are plugged in one or more of the carbs.  If jets are needed, buy Mikuni brand, as first choice.  

Yeh I haven’t did anything yet. I haven’t even taken them off yet because I just put them back on 2 weeks ago after cleaning them thoroughly. I even drilled the caps off the mixture screw to get to them. Bike ran great for two weeks and then went down hill. I should have probably cleaned the tank out @ the same time so I think that the problem lies there but while I’m going back in I was contemplating measuring the pilot jet because I can barely see through the hole with looking into direct sunlight from the garage door being opened and compressed air does go through and ALL passages are open even the passages by the bowl and going into bowl. I compress every passages and all were free and clear.
I am going to order a choke plunger kit and seal that Zed1035 mentioned waiting on cam plugs from Norway coming in on 7/7/25 have complete gasket set going to use the valve cover gasket out of it. Thanks everyone 
Also going to add pics of one project I want to do on a barn find from neighbor and also a brand new seat that I’m not quite sure what bike it fits. I probably could find out myself but you guys will know quicker. This was with barn find. So I have a 1982 and 1983 

Hey Zed 1035 I don’t need this seat I think it’s for a 750 if you know someone who needs it please let me know. I’m not here to make money so I’ll let it go for a reasonable price. It is brand new a little dirty but that box pic has a part # on it.