TOPIC:

I have a kz650 LTD with a touch under 30k miles. Everything is stock, except the pod filters, which I plan to replace with a stock airbox when I finish getting all the parts. The petcock is dead, so I just have a shutoff on the fuel line and leave the petcock on prime. There's an inline fuel filter right after the shutoff, I'm not sure if that is stock. The gas tank is a little rusty, so it is there to stop the rust from clogging the carbs.

The problem I am currently having is that after I ride a few miles the engine bogs down, even on highways going highway speed. If I sit a bit after it dies it will start right back up and be fine for a few miles.

I don't think it is vacuum locked, I cleaned the gas cap and there isn't a sucking noise when I remove the cap. Could the fuel filter be restricting flow just enough to empty the carbs? Or does this seem like old coils that don't work when they get hot? Or something else entirely.

Start with obvious fuel deficiencies. Clean tank. Replace fuel filter. Cut old filter apart and see what is in it .
I would next pull carbs and clean too. Do float bowls have drains you can pull to clear them of fuel and or debris ?
Sounds like you need to go thru and do a complete service / tune up
Dave

Also make sure the fuel line is not kinked. Ed

The bowls do have drains to clean them up. I'll clean the tank and get a new filter. I really should do that anyway even if I had no issues. I'm trying to avoid messing with the carbs too much until I get the rest of the airbox pieces and slap that on there so I don't just have to tune it again.

If the petcock has a screen, treat it with care when cleaning it as a replacement screen may not be available. I'm assuming you plan on removing the petcock when cleaning the fuel tank.




.....

Have the valves been adjusted?
Steve

Not since I have had it, which has been since December. I would not be surprised if it was long overdue.

Start there before going to the carbs.
Steve

I think that is beyond me at this point, what other symptoms would it cause?

How about burned valves and the death of the Bike? It's the most neglected or ignored of all tune up procedures. Many times a bike is sold by the cheap or lazy PO saying it just need carb adjustments.
Steve

Checking the valve clearances is not really difficult, and certainly easier than carb tuning. Changing the shims is more involved, but doable with help from members here.

I would certainly look hard at the fuel filter. If it is a paper element, it may be for a pressurized system, and will cause the problems you describe. Toss it, and get a new one that you know is for a gravity feed system.

I need to buy more tools before I can check valve clearances. I only have a small set of sockets and wrenches, which is a little lacking. I believe I will need a feeler gauge and something to set the torque the screws on the cover properly. Can you think of anything else?