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
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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.
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.
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.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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?
What year is it?
Start with simple things
I would rebuild the petcock and get rid of the inline filter and shut off first.
If your bike only runs on prime then you don't need the extra shut off, just turn it to on, and I may get some flack for saying this but if the filter in the petcock is clean and has no holes then you don't need an inline filter.
Some inline filters(not all) can clog up because they are too fine. any crud that goes through your system only needs to be smaller then your jets to get burned up.
If you rebuild the petcock correctly and run the vacuum hose to the right port the automatic shut off will work again.
The vacuum hose on the petcock (no joke) has a golf tee stuffed in it. Theres a bunch of hoses from the carbs going to nowhere, so I'm gonna have to look up a schematic and figure out what is going on.
Well, I seem to have cleared up the fuel shortage issue, now fuel leaks from an air filter when I leave it on Prime. Ill have new seals for my petcock in probably tomorrow. I also got some vacuum line to actually connect the petcock, which should be pretty easy once I find where It connects in the shop manual. I might try and buy a physical copy, since that thing is a royal pain to flip through in pdf form.
I set up the petcock and got it all working, it still does leak gas from the air filter though if I leave it idle too long, but I went on a nice long ride and I did not bog down. I'm still going to look at the valves though just to be safe, and I should probably clean the carbs, since this overflow would indicate the carbs have something not quite right.
The previous owner did another weird thing: The hoses at the bottom of the carbs all go into a little can he has ziptied to the frame under the right side cover. Where should these hoses actually go to?
I figured out why the original owner had installed pod filters: He cut the battery cage, riveted some bent drawer glides onto it and stuffed a bigger battery in it. This then left not enough room for the airbox. I drilled out his rivets and I'm buying a smaller battery I can fit in the cage once I fix it. I am going with a smaller one, since the original dimension ones are all lead acid with the acid vent hoses and I don't really want that. Being as I have a kickstarter, I only really need something there to complete the circuit and power the lights while I start it.
I've been refurbishing my airbox boots with a soak in a 1:1 mix of 91% isopropyl alcohol and Methyl salicylate.
I need a nice warm day to remove the carbs to install the airbox now.