Not running well and not sounding well

[brad luna]

I have an 86 R piston is weisco 68mm I have fmf pipe and silencer a 36mm keihin pwk air striker, oem air box with tubes, main jet 162 and slow jet 48 and run my fuel 40 to 1 93 octane  with the air screw 1.5 turns out.I live in mid missouri. After its warmed up if you open the throttle up it sounds like its breaking up and sounds like crap when it does. i'm not sure if its jets or needle that I need to work on. I'm not sure what needle is in the carb whatever came with  it when I bought it new last year. I know the clip is set in the middle. I think I need to go up on my slow jet to a 50 and down on the main jet 150. . I just hate it sounding like a piece of poop. I have cleaned the carb recently. I'm thinking about going back to a  pj34mm I think it had better low end with the pj34mm . Any help would be great thanks.

[evaneyeball]

To me it sounds like electrical causing it to ping thats what happend with mine is I overloaded the stock cdi with a very bug long hill and it crapped out then after that it would ping whenever you attempted to get power out of it and always sounded like it was breaking up I've also had that breaking up sound happen because I had a cracked reed pedal thats my thoughts im no expert but thats just the problems I've had

[2ndmoto]

Change one thing at a time. Is the carb a new addition?

[brad luna]

the carb is not brand new i have had it on there for several months and it started leaking fuel from it so I cleaned it to see if that would fix the problem and it did. so I put some different jets I thought my main was a little lean I went from a 150 main jet to a 162 main jet  and dropped my slow jet from a 50 to  a 48 but Im thinking I should go back to what it was because it run alot better with the 150 and 50 in it. Unless something else is causing the breaking up problem.
If it was electrical are you thinking CDI  or what?

[2ndmoto]

To start, I would check spark plugs and spark plug boot. Then move to the stator, then to cdi.

[Jerry Hall]

the carb is not brand new i have had it on there for several months and it started leaking fuel from it so I cleaned it to see if that would fix the problem and it did. so I put some different jets I thought my main was a little lean I went from a 150 main jet to a 162 main jet  and dropped my slow jet from a 50 to  a 48 but Im thinking I should go back to what it was because it run alot better with the 150 and 50 in it. Unless something else is causing the breaking up problem.
If it was electrical are you thinking CDI  or what?

What indicated that the 150 was too lean?  Going from a 150 to a 162 is 5 jet sizes or about 15% change in fuel flow. 

I would put a 155 and test ride it.  If it runs a little better but still miss fires, put the 150 back in it and test ride.  If the 150 miss fires then something else has changed since it ran good with a 150 main jet.  Have you changed to a different fuel, air filter, air filter oil or installed the lid on the air box?  If not, now I would check things like the spark plug, spark plug cap, reeds, stator or CDI box.

[brad luna]

I have always had the lid on the air box will taking it off make a big difference in airflow?   
Nothing indicated that the 150 was to lean.  I had the carb off cleaning it and figured I would try a richer main to see how it worked. when I checked the spark plugs before they looked pretty good. I never done a plug chop and the plug cap that is on it is the one where you have to take the top off the plug otherwise the plug cap will not go on the plug.
What I have noticed is the plug cap does not snap onto the plug it just sit's on top the plug which I would think it needs to be more secure to the plug. I will try the 155 main if I have one if not I know I have 158, 152,l 150 but it could something else if I still have that problem with the 150. I may have fouled a plug to I didnt check that and I should have dont know what I was thinking.... thanks for the input I will see what I can come up with and get this thing running right again.

[2ndmoto]

Plug and cap are definitely suspect. With jetting I always like to get a base line of the motor to make sure I am not jetting to a unhealthy motor. Make sure you are getting a nice blue spark. Check reeds, compression and leak down. Make sure the pipe and silencer are clear of obstructions/heavy build up.

Removing the air box lid will allow for more air flow. I would recommend removing it if conditions allow. If you are running it mud or water, leave it on, otherwise invest in a prefilter. They do make pre filters that go in place of the air lid also.