Other than tuning jetting is you're best bet does she smell rich? I'd assume she needs to go down a size or two...also is the intake on the engine the same I.d as the new carb?

 

yes the intake manifold is 24 mm as is the carb at the intake side .although the hole on the head where the intake manifold bolts up to is a little smaller in diameter. would moving the needle down a clip fix my problem?
thanks

 

Yes as rich? Moving the needle clip up will lean out the first bitofthrottle...but I'd assume you're like2 jet sizes to fat...that is if the carb is correctly adjusted to spec......followingquestions...pipe?little open air filter thing like a coldairintake?

 

Moving the needle changes the midrange, not the first part of the throttle. Also, don't try to see how it runs by just revving the crap out of it sitting there without load, it won't tell you much. Get on and load the thing and then see what it does.

 

That's the biggest thing under load! Here is a good visual of what's goin on

 

It has a upgraded pipe and a cold air intake so i guess I would need a leaner jet ? it has a 95 main at the moment . It revs up fine if I roll in on the throttle but if I just open wot fast it hesitates a little and then revs up. I cant ride it yet because I need a new master link i don't think revving it up high will do anything though since it has a stock cdi that limits it to 7500 rpm.

 

Revving in neutral is bad...some is ok but no reason to go to the limiter ...it's bog will get worse with ur weight on it...get you're link ride try to tune then order your jets..you might b able to work it out..but yes leaner I'd assume

 

The more power a motor makes, the more fuel it needs usually. So if anything that is done has increased the power then it needs more fuel to correct the mixture. So I would think that it needs to go richer. The 95 is a bit small for a 125, try a 100 or 102. But the main jet is the top end and your problems are lower down you say, so lift the needle or lower the clip a notch at a time and see what that does. Also try screwing the idle mixture screw in a 1/4 turn at a time and try that. All this while riding, not just sitting there and revving it.

 

Ok I tried turning in the air screw to half a turn out and it works better but still bogs a little at 1/4 throttle. Can the carb work with the air screw all the way in?

 

Now you need to go up a size on the pilot jet, and reset the air screw to 1-1/2 turns from seated, and see what happens. If need be, as stated above, use 1/4-turn increments IN to richen it and eliminate the off-idle hesitation.

 

when it goes in it gets leaner it idles to fast at the moment and gets worse the more I turn it out 15 is the smallest pilot jet for mikunis

 

Can you post up a pic of the carb you have? It sounds like you have a carb with a fuel screw instead of an air screw.

 

A 15 idle jet is too small for most of these motors over 90 cc, go to a 22.5 maybe

 

Heres a pic of my carb I got tired of messing with it and I put my stock carb back it feels more powerful with the pz 19

 

That is the standard 22mm Mikuni-clone carb that comes with quite a few of the Chinese pitbikes. That carb does have a fuel screw, you turn it out to richen the mixture. The baseline setting for those carbs to work from was a #20 or #22.5 pilot jet, a #100 or #105 main jet, the jet needle clip in the 4th notch from the top, and the fuel screw at 1-1/2 turns out from seated, as I recall. Those baseline settings were for sea level.

 

Good information here, I have the same piece of crap carb on my YX140 and wound up with a 20 pilot, 100 main, needle clip in middle notch, about 2 1/4 turns out on fuel. When it runs good it's on but it's a tempermental piece of crap, needle sticks a lot too, don't put any ethanol fuel in it. I keep saying I'm going to order a genuine Mikuni VM (not a crap clone) for mine.

 

Its a 24 mm at the opening , I got it running ok on my 125 today but I don't really feel an increase in power maybe a little more top end speed but less torque. The bike idles a little high wouldn't bigger jets make this worse ? I live at least 1000 ft above sea level. I also have a 22 mm carb which seems to be much lower quality , it was a replacement for there crappy carb that broke on installation. The carb in the pic is not to bad much better quality than the carb it came with, the mikuni jets at cms fit as well but its not as good as the mikuni on my kx125.

 

OP, I have been telling you as have others, that your setup is too LEAN, either ask us for info and then follow that info you get, or if you dont like what we say, then quit asking.

 

Well is there any way you can explain it I don't respond well to orders I need to know why it works better that way I don't go spending money based soley on what you say with out an explanation. Such as does a bigger pilot jet lower the idle or increase it?

 

Do you understand the idea of Stoichiometric or Theoretical Combustion ? it is the ideal combustion process where fuel is burned completely. 13.7:1 a/f without knowing the basics of a/f ratios you won't understand what's doing what and why it's doing it...here's a chart if this doesn't give you what you need you need to do some time researching

 

I got a PZ26 on my 125cc and it seems to run well.

As others have said the engine needs to be under load. The best thing to do is the get a new plug, fire up the engine and DONT let it idle, immediately take off in 2nd or 3rd and get the engine up to speed and hold for a minute or two, then kill then engine. Dont let it idle.

 

What was posted above is a good way to jet your main jet. The plug should be brown in color. Black is to rich and white to light brown is lean. Your needle can also be jetted the same way but you need a new plug every time you check. The pilot and air screw can be checked with the bike on the stand

 

Well I looked it up and it says I need a new pilot jet when I have the screw air screw richened all the way or if I can start the bike without the choke on. Which is the only way I can start the bike even with my pz19. So according to the research I need a leaner pilot jet but I already have the smallest one I can get. When the 24 mm mikuni worked ok I had it at 2 1/4 turns out , but the bike still idled to quick even with the idle screw all the way out. I felt more top end but a lot less low end grunt I guess ill try raising the needle clip up a step.

 

Take a pic of both of the carbs and on both sides. A few carbs have a vacuum port on the engine side of the slide to open petcocks. Also some carbs have an oil injection port.

24mm carb ,If your carb has any of the ports it will cause an air leak and a high idle.

Pz19, is that carb new or used are the jets new or used. I have seen a trend of people drilling out jets to make them richer. Please no one do it!! Just spend the 3 bucks and buy a new jet. So if there is any question about or a possibility of the jets being drilled just buy new jets.

 

ok I see if I can take a pic tomorrow the pz 19 came with the 125 the previous owner never messed with the carb he never even tried to make it idle. thanks

 

wonder why your lifan125 came with a 19mm carb and mine came with a 22? i have a brand new 22mm carb if you want it. $30