The carburetors need a thorough cleaning. Since you're posting here I suspect you aren't comfortable with rebuilding/cleaning constant-velocity carburetors. Member
dannymax is a place to go to get your carbs refurbished, send him a PM.
There are also other members who sell new and used parts, and who do repairs on the VMax. Sean Morley
[email protected] is a builder of anything from OEM-spec bikes to forced-induction, big-bore mountain motors.
CaptainKyle is another member who can rebuild your carbs, or replace the faulty parts in a transmission, 2nd gear being a notorious place for VMax problems. I suggest that you do whatever is needed to get the bike running properly, and then see if second gear is in need of repair. If it jumps out of second gear on hard acceleration, then you have to decide what to do, as fixing it properly will require in most cases replacement of several pairs of gears. Sometimes you can luck-out and have it be the shifter drum, and loose/missing pins in the early years' bikes shift drums. A later model pin assembly will usually fix that. These things all take knowledge time, and $ to fix. That's where using the factory service manual comes in and being familiar with motorcycle mechanics. "If you don't 'know motorcycles,' know your motorcycle mechanic," is the saying.
Behind the steering head is the electronic ignition for the bike. MSD is a supplier of ignition components. CARB is the CA state agency governing approved alterations to the running gear, so something in your bike probably has an MSD component or components in it. The sticker is there to show compliance with the state of CA regulations for replacement parts. Post a pic of your coils under the seat. Compare them to the coils also behind the steering head. One of the products MSD makes is ignition coils. I do not know them as a manufacturer of replacements for the OEM ignition boxes.
Your 4/2/1 exhaust is a good one for making more horsepower. It does that if the jets have been replaced, the main jet is probably reduced from a 152.5 to a 150 or a 147.5 main. You have to disassemble the carbs to access the float bowls, remove them, and then you can see the main jets. Other jetting changes likely need to be done to have a
full complete exhaust, headers, collectors, and canister(s) perform best.
I suggest you use the search function in the upper-right, and do reading on aftermarket
full exhausts and also on carburetors, carb kits, carb cleaning, and what to do to resuscitate a VMax having been sitting for months or years. There are hundreds of posts on these subjects, maybe thousands. However, your best approach is to read as much as you can to gain knowledge on these subjects. An informed consumer, you could say.
Some things to help you get started.
https://dn790009.ca.archive.org/0/i...ice-manual/yamahavmaxvmx12-service-manual.pdf
https://www.vmaxforum.net/threads/new-vmax-owner-faqs-new-members-please-read.21240/
https://www.vmaxforum.net/threads/half-throttle-sputter-hiccup-when-vboost-hits.53057/#post-532569
I suggest you add your location below your avatar, and in your 'signature line' add the year of your bike, and any aftermarket pieces on it. That might take some input from members on here, seeing your pictures of your bike. I suspect your exhaust is a 'Holeshot Performance' full exhaust.
Post pics of your bike from both sides, in-focus, and from squatting down next to it, so the pictures will show maximum detail, so we can see what you have. Are there any rocker switches sticking out of the plastic guards by the ignition switch, or on the left, attached to the black plastic trim pieces above the aluminum airhorns?
