Still Having Problems

MrLarkins · #1 08-19-2008, 09:14 PM

This is frustrating...I still can't get my bike over 20 mph. I use to get 30+ easily. Now it bogs do when i get to 20mph. I have lots of throttle left, but it only starts to chug when I use the rest of the throttle. My mixture is right, my clip is on the highest point...could the fact that I ported my exhaust have caused this somehow...maybe causing a backflow air problem?

I'm grasping for straws here.

Ghost0 · #2 08-19-2008, 11:50 PM

What does your plug look like?

Pablo · #3 08-20-2008, 07:28 AM

What kind of plug is it?

MrLarkins · #4 08-20-2008, 08:24 AM

the plug is black and sooty...and I am sure that my ratio is 44:1 ! It shouldn't be black and sooty with that ratio...the thing is, the first quart turn of the throttle the engine runs perfect. but after that the rest of the 3/4 turn of the throttle the engine bogs down, chugs, and won't rev past that rpm...that would probably explain the black and sooty plug...its getting more gas but is not burning it...right? so why not? why is there a barrier? should i video it or something?

Ghost0 · #5 08-20-2008, 08:38 AM

It sounds as though you are running into a rich condition at full throttle. You may need to go to a smaller jet. You can buy a new one or do the solder and drill trick. I found that after modifying my intake and exhaust ports that it ran richer and I needed to make the jet smaller. Here is the drill kit that I bought.
25pc. Carburetor Drill Kit I also attached a drill chart for reference.
In my opinion these carbs are jetted to deal with all of the issues the engine has, intake leak and poor fit of intake and exhaust manifold. By the time you fix these things the carb is no longer jetted correctly. You can double check that the rich condition is your issue by running the bike at full throttle and slowly applying a little choke. If it runs better with a little choke you would need a larger jet, if it runs worse you will need a smaller jet.

Pablo · #6 08-20-2008, 09:22 AM

Agree with the overly rich condition. Just dropping down to a .65mm jet without even selectively trying other sizes nearly eliminated any high RPM rich 2-stroke symptoms, but hold the phone because I'm still tuning.

Ranger · #7 08-20-2008, 11:58 AM

Have you tried a thinner air filter? Or just simply taking off what ever you did to the exhaust?

A smaller, less dense air filter and a bigger exhaust pipe should help.

MrLarkins · #8 08-20-2008, 07:05 PM

i guess ill try to 're-jet' it

what is the process? do i need a new needle? or do i just fill and redrill the whole and keep the same needle? if i need a new needle, where do i buy it?

**Norman** · #9 08-20-2008, 07:54 PM

you don't need to mess with the needle sounds like your main jet's hole is too large. try to find out what size it is by using a set of micro or carb jet drills so you will know the jets size that it is now.
then solder it shut. I solder them shut and redrill them to either 0.025 or 0.026 thousands.
If you don't mind a wait I can do your jet just let me know all I will need is the main jet. look at my carb post and you will be able to see just what I'm talking about.
Norman

MrLarkins · #10 08-21-2008, 07:11 PM

what effect would an UNDER inflated tire have?