Jetting for MikesXS Mikuni carb kit on XS400 Maxim?

I just picked up a Maxim last night with the MikesXS carb upgrade kit. He said it was too rich (makes sense) and the bike was blowing sooty exhaust when he started it. Anyone done this mod to an XS400 and know where I should start with jetting? It also has an aftermarket 2 into 1 exhaust on it. See pics. He also mentioned about soldering the jets closed and using pin drills to save $$$. Anyone?

 

Does it start easily and/or idle? What jets are currently in the carburetors? Jets can be had at Steven's on M-13 just past Wilder Road.
They are the Mikuni main distributors. I'm from Saginaw and go to Stevens all the time. BTW I would never solder jets, likely you only need a new main jet x 2.
Cheers, 50gary

 

Man that’s a blast from the past! Lived in Saginaw and Freeland in my teens and early 20’s. Went to that place all the time, great staff back then that went the extra mile to help me with my old (even then) bikes. Hopefully still as good, haven’t been there in 20+ years.

Hijack over, carry on.

 

Are you the speed skater? We've met before

 

Yes, Short Track Rules.
Cheers, 50gary

 

I went out today and it started easily (45+*F outside) and stayed running but it is super noxious and smells uber rich. I haven't checked to see what jets it has now yet. I just bought the bike a couple nights ago. I will also pull the plugs and see what they look like. I was impressed with how strong it ran until I couldn't take the smokey fumes anymore...

 

The plugs will be black just a WAG ha! If you have the correct Mikuni jet tool, you can simply loosen the hose clamp and rotate the carburetor then remove the big hex nut from the float bowl bottom.
This will allow access to the main jet (using the cool tool) without removing the carb altogether, check the jet number, easy peasy.
Cheers, 50gary

 

What about the pilot or the needle position?

 

Pure guess here, but if it starts and idles okay the pilot is probably at least close. The needle position can be removed without
taking the carb off simply by screwing the top cap off, middle, clip should be in middle position to begin the tuning process. What size are your carburetors?
Cheers, 50gary

 

32mm I think. Whatever mikesxs kit is

 

@50gary we should hook up and shake this thing down if you're willing. I'm in Bay City right by Bay Valley and Delta College.

 

Here ya go, beginning specs for 32m VM rnd. slide genuine Mikuni:
Main. 160
Pilot. 25
Needle jets. 159. P-6
Jet Needle 6F4
Slide. 3.0. clip in middle position
Air jet 2.0
Cheers, 50gary

 

Sorry they are VM34 34mm

 

https://www.mikesxs.net/yamaha-xs650-mikuni-vm34-rh-carb-generic-jetting.html

 

At this point just take the carbs off and check the jets and settings write everything down. Likely something or several things are way off but you must know first where you're at before you know where to go.
The 32m will still give a reference.
Cheers, 50gary

 

Rode it today. Won't idle without throttle input. Revs strong, then flat, then revs hard. Plugs are black, exhaust is spitting soot. I need to find someone to help me here. It's beyond my ability/understanding of Mikuni VM tuning.

 

I don't know squat about it either, but I do have this link handy: http://www.vintagebikebuilder.com/mikuni-tuning-and-jetting-guide.html

 

Thanks. Better than what I have. Time to get a box of spark plugs.