You don't need to remove the carb to replace jets, but you will to drill the a/f screw.
Remove the air cleaner, and backing plate. The backing plate on the Evo is basically the mount that stabilizes the front of the carb. Unhook the fuel line and both throttle cables. Although not necessary, I mark one of the cables to make sure I don’t get them mixed up. It’s hard to mix them up, just due to their length difference, but anything’s possible. To loosen the throttle cables, just uncover and unadjust the cable adjusters near the throttle, under the little, black rubber boots. Shorten the adjuster, putting slack in the cables.
You’ll also need to unhook the VOES vacuum line and the float bowel overflow line. Just let them hang.
On the left side, (shift lever side) you need to unhook your choke cable. It’s a 5/8” nut on the back of the mounting bracket/motor mount. It’s easier to unhook the choke there, then off the carb, IMHO. Once your cables, fuel line and cables are disconnected, the carb pulls out of a rubber grommet/seal that’s in the end of the intake.
Once off, I drain mine by removing the bowel over a container. With the carb upside down, and the bowel off, you’ll see the float, and two ports for jets. The larger port (top) is for the main jet, and the smaller one (at about 9 oclock) is for the pilot jet.
This carb is stock. It’s so virgin, the a/f mixture screw was still capped. Too boot, the factory a/f setting on the screw was barely 1/8th of a turn out. Yep…..from the factory.
Stock jetting for this was 165 main and a 42 pilot. I have Reinhart pipes, A/N air filter and an SE cam . I run a 180 main and a 48 pilot. The jets are brass and soft, so no need to tighten them like a lug nut on a dump truck. You'll not how long the main jet "looks" in this pic, because it's still attached to the emulsion tube. Separate them to replace the jet.
Take care not to hit or press on the float, as you’ll have to reset the float level again, and that’s another story for another day. Not difficult, just another few steps. Put your float bowel back on, before taking anything else apart. Sometimes it helps to have a small selection of jets, to be able to change them at will, for best running results. Numerous jets come with a Dynojet kit. Others can be bought at your dealer for a few bucks.
You can get a shorty screw driver and remove the bowl screws. Hold the carb tight, and try to hold the screwdriver as straight as possible. If they're still stuck, you'll probably be better taking the carb off and do it that way, as to not strip a screw.
Here's some more info:
Here's a needle jet, dismantled from a carb. (a spare....not off my bike.)
You can see the carb top, diaphram spring, disphram with slide, plastic spring seat and the actual needle. This one is a Dynojet needle. It's adjustable. It also has a fat taper (#D147) and is a rich needle.
I also laid out 2 more needles, including a narrower taper Dynojet needle, and a stock needle, N72V, which is a nother rich running needle. Note the tiny washers next to it used to shim it with. THAT'S what you need to get for yours, unless you replace the needle.
Here's a chart to show you the various needles, widths and ranges of rich/lean.
Linear Mode
