KZ200 bogging down / stalling

Hello all! Long time lurker here, tried for a while to figure this out but I'm not having much luck. I did a rebuild on a 78 kz200 I've had for a few years, and I just can't get it to run right without fear of getting stranded somewhere due to it dying.  It keeps dropping rpms when I pull the throttle, especially in 1st and 2nd gear.

I replaced the box air filter with a pod filter, then changed the pilot and main jets to accomodate a new fuel / air mixture from that new filter. I also replaced the condeser and am planning on replacing the points soon (it kicks back when i try to kick start it, i reset the ignition timing but it's still occurring - different issue, I know, but any insight would be awesome on this too!)

So, something is causing my spark plugs to continue to foul, (still not sure what's causing this). It idles like a champ, but when i pull the throttle it bogs down. I went a few sizes larger for the main jet (shifted from 108 to currently at 115 now) because I think it wasn't getting enough fuel. The bogging issue is still happening, so I went ahead and ordered a new fuel filter in case that is the issue.

SO that brings us to today - what might be causing this? Help!

Thank you!

Fouled plug indicates a too rich mixture or a very weak spark, or burning oil.

If the air filter is a cheapie one, it may be blocking the air intake ports in the mouth of the carburetor. It can also be caused by the fuel level being much too high.

Be sure the fuel filter is made for a gravity feed system. If you use one for a pressurized system (has a fuel pump), it will likely stop flowing after a few minutes. Then you will have the leanest mixture of all.

P.S. This part of the forum is for new members to introduce themselves. This post belongs in either the carburetor or engine forum.

TexasKZ wrote:

Fouled plug indicates a too rich mixture or a very weak spark, or burning oil.

If the air filter is a cheapie one, it may be blocking the air intake ports in the mouth of the carburetor. It can also be caused by the fuel level being much too high.

Be sure the fuel filter is made for a gravity feed system. If you use one for a pressurized system (has a fuel pump), it will likely stop flowing after a few minutes. Then you will have the leanest mixture of all.

P.S. This part of the forum is for new members to introduce themselves. This post belongs in either the carburetor or engine forum.

Moved 

Hello!

Thank you TexasKZ - do you have a recommended air filter? I'm not sure I even remember the brand of the one I got, but it may be a cheapie one. How would I diagnose if it's a weak spark, rich mixture, or burning oil? I had the same thought that it must be running rich if it's fouling plugs, but I think the bogging was happening because it was too lean/not enough air coming in.

Would it help if I attached a video of it?

The factory setup works really well, especially on stock engines.
If you must stay with the pod style, then APE, K&N and Uni Filters are excellent.

One way to test for weak spark is to take the plug out, then plug it back into the wire and lay it on the head with the plug in contact with metal. Turn the key on and hit the starter. Watch the spark carefully. If it is small and yellowish or white, it is weak. If it is strong and blue, it is probably ok. It will be easier to see in the shade.

If the plug is black and wet, especially if you see blue smoke from the exhaust pipe, it is burning oil.
If the plug is sooty, black and dry, especially if ththere is black smoke from the pipe, it is a very rich mixture.

A really rich mixture can also cause bogging. Why do you think it is too lean?

Lean means too much air, rich is too much fuel.