What are your jet specs?
 

I'm curious to see what everyone is running on these 125cc engine. I see everything from 110 to 195 main jet online. I've got a Vm26 carb with a 110 main and 22.5 pilot. Pod filter and stock exhaust. It runs out alright but definitely feels like it needs more fuel. I'll have a jet kit and new exhaust here in the next few days to experiment further.

I have the same carb on my Razkull, with stock exhaust, If I remember right I'm running a 120 main. still tweaking on mine as well. I had a 125 jet in it, and it would bog in the mid rang when warmed up, it runs better on the 120, but I think I might be a little lean at wot.

If the 125 is better at WOT, try leaning out the needle jet 1 notch (assuming your needle has more than 1 clip position).

I'm running 130 main and 25 pilot I think. Where are you at? I think altitude will affect it a bit as well.

I'm currently running a 22 pilot and 149.5 main on a Vm26 with stock exhaust with pretty good results. Will be throwing in a 155 main when my exhaust gets here

my 26mm carb came with a 95 main jet, I swapped it out with a 110 and it ran better, however it began acting up once it was warmed up, if I stopped at a light or stop sign, it would want to stall out, it did not like to idle at all. I swapped it out with a 105 and it got a little better, but not as smooth as it was. When it would stall out, it would crank over and over, but wouldn't want to start back up unless I 1/2 choked it, then started up... any advice? I have a 27mm carb coming tuesday and that one looks easier to get to the air/fuel mixture screw, so I'm just waiting on that. But would love to jet this out to a 150 or bigger jet. I'm not too knowledgeable about carbs for say, just been a clean 'em and install them kinda a guy. now that I have a 125cc bike... its everything I can do to get more power lol

The main jet has nothing at all to do with the idle. You needa different pilot jet or to at least adjust the idle mixture.

Thats kinda what I thought, main jet is for half throttle and up, but I swapped it out today and put in a 125 jet, ran about 20 miles, and it runs pretty good now, I do think I need to adjust the air/fuel mixture, I'll see how the 27mm carb runs with the 125 jet in it when I get it. I did however stop getting gas at my usual place and started getting it else where... seems to idle better now... could have been just crappy gas (even tho they sell it as super unleaded). So for a 125, whats the max I should jet it? without long term damage :-)

Nevermind, I found my valves needed adjustment, got it running good now, idles great, picks up and goes, and gas mileage is better. I went down to a 105 jet for now.. waiting for my next exhaust to come and then re-jet to that... These bikes are fun to work on, best part is if you mess up, its cheap to fix, unlike working on a bigger more expensive bike...

As far is jetting, its my understanding that the outdoor temperature has a lot to do with it, again, I don't know much about jetting, as it gets warmer which way do you go with the jet? up or down? and how warm are we talking? I'm riding around in 50 degree to 60 degree weather now, just looking for some advice

The general idea is that as the temperature drops, air becomes more dense, therefore requiring more fuel. As the temperature increases and air becomes "thinner", you'll need less fuel. Let's say you're using a 25 slow jet during temperatures above 70F; you might increase to a 27.5 or 30 if it drops to around 32F. Similar logic applies to the main jet.

Thank you, I have a better understanding of it now.

My 125cc has a Keihin clone carb. It came with a #90 jet. I jetted up to a #95 when I mounted an aftermarket exhaust.