Do I need to mess with my carb?

[gr4vitas]

2016 300 RR (non race) stock carb settings.

Sea level with summer temps between 70-90 degrees. Average riding range is from about 500 feet to 2000 feet.

It's been a bit since I was on the bike (winter) and all last summer riding I didn't notice any kind of bogging or hesitations etc but I also wasn't really looking for them. I mostly picked it up from the dealer at the beginning of last summer and rode it, I did at some point try to mess around with the idle some as it was idling really low. Not knowing what I was doing I just turned up the idle knob a tad and called it good for a short while. Then after doing some reading tried messing with the air screw.

At that time I recall it seemed like the air screw didn't really do a whole lot for me. Idle would maybe change just a tad bit from fulled in to 2 turns out but not significantly. If I recall it would still idle at full close as well no problem. Anyway I gave up and just put the air screw back to stock according to the manual and pretty much left it at that.

Again no bogging that I recall or hesitations but as I said I wasn't really looking for any ether, I'll maybe have a better idea in a month or so when it warms up some.

I did have the head off mid summer and there was a decent bit of black carbon on the piston, not edge to edge but probably 75% of the top of the piston had a good build up of dry black hard carbon on it. Plug was also all black but dry. ( I didn't do any kind of wide open / kill switch before pulling the head)

You can see the cylinder in this video, I've linked it to the exact time:

https://youtu.be/-3bW0BD5U_0?t=644

The one thing that seemed off to me was when I started the bike when it was cold unless it had been sitting outside the garage in the 80 degree temps for a while it almost always needed the choke. The garage of course is always pretty cool even in the summer heat, it probably sits around 60 degrees in the summer even when its 90 out.

Also when I do use the choke to start it, right when it starts up it starts to kind of wind out RPM's wise a little more than I feel is normal. It starts up with just a tap of the button but then over the course of a second or so it winds up to like 1/3 throttle it seems like. I always shut the choke off immediately because of this weird behavior, usually I just have to give the throttle a couple blips right when I start it up and it will idle okay and warm up but it will NOT start without the choke on though I can shut it off immediately. It does like I said require a little attention or she'll stall out but a few blips usually keeps it going okay.

TLDR -
Anyway I'm wondering if theres something I should be changing about the jetting. Air screw doesnt seem to make much if any change from closed to 2 turns out. Winds out to what seems like 1/3 throttle when I use the choke at start up (slowly climbs in revs over two seconds).

Wondering if I should put in this mythical NECJ needle or something? I dunno I'm a noob to carb jetting though I understand the basics.

[farmerpaul]

Here is an extract from a very good article I found on the MXtracs forum.

I have used this method myself and it works.

You just need to be patient, methodical and take notes of what you have done. Oh, and only change one thing at a time.

Good luck.

++++++++++++++++++++++++++++++++++++ Start of article ++++++++++++++++++++++++++++++++++++++++++++++++++
It's very important that you start with the pilot circuit. The reason is simple. The pilot circuit affects the entire throttle range. When you are at full throttle, the main jet is the primary fuel metering device, but the pilot is still delivering fuel as well, adding to the total amount of fuel that your engine is receiving.

Before you start to rejet your bike, you need a clean air filter, a fresh plug (actually you need several plugs to do plug-chop tests for the main jet), and fresh fuel. One important detail: Make sure the engine is in good mechanical condition. If your engine has a worn top-end, fix it first. Trying to jet a worn out engine is a waste of time. The same goes for reeds that don't seal properly, and a silencer that needs re-packing.

Before you start the jet testing, Install a fresh plug. Warm the bike completely, and shut it off.

As already stated, start with the pilot circuit. Turn the air screw all the way in, then turn it out 1.5 turns to start. Start the engine, and turn the idle screw in until you get a slightly fast idle, or hold the throttle just barely cracked, to keep the engine idling. Turn the airscrew slowly in, and then out, until you find the point where the idle is fastest. Stop there. Do not open the screw any farther, or your throttle response will be flat and mushy, and the bike may even bog. This is only the starting point, we will still have to tune the air screw for the best response.

Now is the time to determine if you have the correct pilot installed in your carb. The air screw position determines this for you, making it very simple. If your air screw is less than 1 turn from closed, you need a larger pilot jet. If it is more than 2.5 turns from closed, you need a smaller pilot jet.

Once you have determined (and installed it if it's necessary to change it) the correct pilot jet size, and tuned the air screw for the fastest idle, it's time to tune the air screw for the best throttle response. Again, make sure the bike is at full operating temperature. Set the idle back down (the bike should still idle, despite what you read in the Moto Tabloids), and ride the bike, using closed-to-1/4 throttle transitions. Turn the air screw slightly in either direction until you find the point that gives you the best response when cracking the throttle open. Most bikes are sensitive to changes as small as 1/8 of a turn.

The air screw is not a set-it-and-leave-it adjustment. You have to constantly re-adjust the air screw to compensate for changing outdoor temps and humidity. An air screw setting that is perfect in the cool morning air will likely be too rich in the heat of the mid-day.
+++++++++++++++++++++++++++++++++++++++++++++ end of article ++++++++++++++++++++++++++++++++++++++++++++++++

[gr4vitas]

Here is an extract from a very good article I found on the MXtracs forum.

I have used this method myself and it works.

You just need to be patient, methodical and take notes of what you have done. Oh, and only change one thing at a time.

Good luck.

Thanks Paul, I'll certainly give this a shot when I can. I've tried a similar thing before but I couldn't seem to get the idle to change much with the air screw, seemed like it wouldn't change or changed very little going all the way from closed on the air screw to like 2 turns+ out. Bike just kind of sat there and idled. I'll have another look at this though as soon as it warms up.

[farmerpaul]

Once the bike is properly warmed up turning the air screw all the way in should pretty much stall it (as you are starving the pilot circuit almost entirely of air).

I wonder if you need to clean your carb. Maybe you have a small piece of crud stopping it from closing all the way.