Here is a copy of what I found on an old post that is pretty step by step.
It should tell you everything you need. Post any questions because plenty of people here have done the mod.
Vulcan 750 Air Cleaner Removal
My bike is a 1999 VN750. The only changes I had made previously were to install a set of Vance and Hines Slashcut exhaust pipes and coasters. I live at sea level in Houston, TX. The main jets can be changed with the carbs on the bike. The pilot jets require the carbs to be removed. Removing the carbs is about a two hour job and if you know a good mechanic you may just want to pay them to put the pilots and main jets in. Sherm's may be able to get all of these parts, I happened to buy some from Chaparral.
Stock was: 133 main jets, pilot 38
Qty Part # Distributor
2 K&N RC-2340 Air cleaners Chaparral, $22 each
2 Main jets, size 162 Sherm's (I am going with 140, maybe 142 for rear), $4 each you may want to buy several sizes above and
below the 162 to try for your bike
2 Pilot jets, size 40 Sherm's, make sure you get the ones that have threads on a
"step down", not the ones with the same size shoulder
threaded, $4 each
4 Needle shims Sherm's, $1 each
1 Vacuum feed plug, 7/32" Auto parts store, $3
2 Coasters if you don't have them Adam [[email protected]
], about $40, you can use
2 Crankcase breather assy. #14-20900, $15 ea., EMGO, Sherm's
4 3.5" (?) hose clamps For intake manifolds, Stainless, auto store
5 1/4"-5/8" hose clamps For vacuum hoses, stainless, auto store
1' 5/16" Fuel line Auto store
1 90 degree elbow, 1/4" Hardware store
1' 1/4" copper tubing Hardware store
2 about 5/8" long bolts, washers Stainless, metric get them at hardware store
Sears Reversible Ratchet Offset Screwdriver Set ( only needed for changing main jets with carbs on bike)
I also recommend a pair of 8.5" straight Hemostats for playing with hose clamps and getting dropped bolts.
A small tubing cutter is helpful.
1. I put the bike on the center stand to work on. Pull the seat and the gas tank.
2. Remove the air filters, housings and rubber connector hoses to the fresh air plenum under the tank. I put the air cleaner mounting bolts back on the bike.
3. Install coasters if you haven't already.
4. Remove the left side exhaust fresh air inlet hose from the fresh air valve. Remove the right side exhaust fresh air inlet hose from the fresh air valve. Remove the right side carburetor vacuum hose from the right side carburetor and the fresh air valve. Plug the right side carburetor vacuum lead with a vacuum plug. Remove the fresh air inlet hose from the fresh air plenum under the tank and the fresh air inlet valve.
5. Remove the fresh air valve.
6. Remove the air inlets to the carbs from the fresh air manifold under the tank.
7. You now have two choices:
A. install the Main jets with the carbs on the bike and go to someone to remove the carbs and install the pilot jets and shims (if needed). It should run good enough to get you a short distance, it will be lean at the low and mid range. Hint: use the vacuum hose from the right side carb that you removed to start the main jet. Just stick the main jet in the hose with the threads out and screw it in.
B. If you remove the carbs (take the cables out of their bracket before you try to slide the carbs out) and install both the pilots, the main jets and shims (if needed) then replace the carbs.
8. While the carbs are out, you can get your mechanic to remove the mixture plugs or you can use a 7/64" drill, drill the mixture screw plugs on both carbs, start a wood screw into the hole and pull the plugs out. Be careful, don't drill too far in!
9. Install the carbs.
I may not have to do steps 10 and 11 since I have removed the air box and have more room.
10. To get the carb vent or equalization feed to fit without kinking I had to do some rigging. I cut about 1/4" off the EMGO filter (you could use a hack saw or Dremel tool). I also cut one of the "step up" shoulders off of the 90 degrees elbow. I then used two small hose clamps and 7/8" of the 5/16 fuel line to attach the cut end of the elbow to the EMGO filter. Cut 1" of the copper tubing and put this into the existing shoulder of the elbow. Put the other end of the copper tube into the carb vent/equalizer. Bolt the Emgo filter to the top bolt of where the old right side air cleaner went using a longer bolt.. 11. Cut 1" of the 1/4" copper tubing. Cut 5" of the 5/16" fuel line and put the copper tubing in one end until the tube is flush with the end of the fuel line. Disconnect the end of the crankcase vent hose from the air plenum. Put the end of the 5/16" fuel line with the copper tube in the crankcase vent and clamp (the copper tube will keep the fuel line from collapsing). Put the other end of the 5/16" fuel line on the EMGO filter and clamp it. Bolt the Emgo filter to the top bolt of where the old left side air cleaner went using a longer bolt..
12. Install the K&N air filters.
13. Put the gas tank and the seat on.
14. Turn both idle mixture screws out 3.5 turns.
15. I recommend having the carbs synced, they should not have to pull them to do it.
You may need to adjust the shims and main jets to your riding style. I use the stock plugs and 89 octane gas.
1. Used crank breather filter, vacuum hose adapter, mounted in old air filter location, filter paper facing air flow. Running great, Plug color looks pretty good, maybe a little lean in the front cylinder. 2 turns out on the idle mixture. 165 back, 170 front. I have a slight flat spot in midrange, maybe it needs shims?
2. 2 shims under each needle., 161 back, 165 front, 40 pilot runs great low end, seems flat high end. Seems like I go straight from white plugs to plugs with black on them
3. Switched back to 161 rear and 165 front, runs great!. Front plugs are a little dark, rear plugs are a little light. Drop front to 163/2?
4. Switched front to 162