83 KZ750 running issues...

I purchased my bike a couple weeks ago and have been riding it a little here and there, but after a long ride it'll end up bogging down and eventually turning off(like it's running out of gas). I'll let it sit for a while and it has trouble starting but eventually cranks up again, runs fine for a while(maybe 30 or so miles) and bogs down again. I know I need to go through the carbs and there are a couple things here and there that need to be adjusted, but why would it keep starting up fine and run for a while and then shut off? Here are a few things to know...

-When I went and looked at the bike it was idling really high, so I adjusted the throttle a good bit and it calmed her down a great deal(I was thinking, maybe it was running too rich and flooding after riding for a while?)

-I've replaced the fuel hoses and fuel filter

-Topped off with high test and ran some fuel system cleaner through it(not seafoam, would that help? I've heard mixed opinions)

I'm not a first time bike owner, but a first time OLDER bike owner and would love to do as much as I can myself.

ANY IDEAS?!?

Thanks in advance for your help!

Fuel line/ filter restriction, or tank Vent blocked. Remove your Fuel line from the carb TEE and see what the flow is. Compare to no Inline Filter, you may have gotten a filter for a pressure, instead of gravity system. then it could be the Screen in the Tank, above the petcock, that's worth checking. Then there are small Screens above the Float Vale needle and seat assy, at the carb inlet.

it also happened before I replaced the fuel filter. I don't know if that would make a difference. Thanks so much though, that gives me something else to check and I sure hope that's the only issue. haha

It would be worth checking the valve clearances. Not as difficult as it first looks and many people neglect this. If the valves are tight when cold then when the bike heats up they expand and dont seal as well as they should. BIke cuts out and will start again easy enough from cold. You can find a shop manual here kz.bike-night.com/ Scroll down to find "the Bible"

In general it would be good to give it a good thorough service and check also the autoadvancer under te timing cover, adjust the cam chain tension and leave the carbs until the very last - they might need cleaning and synchronising.

Good luck

I was thinking fuel filter right up to the point where you said you already replaced it.

I'd check out the petcock like Dylan said. I've got a '79 and my petcock has a little sediment cup with a screen in the bottom of the petcock. If your's has something similar, take it apart and clean it.

yeah, there was an old filter on there and it was real nasty, so it still could be the filter thing. i'll post updates as I progress. Thanks for everyone's help.

had the problem too. would run great for 2 miles then pthh. I pulled the carbs, removed the floats and jet pins and had carb 1 and 4 with a nasty build up of what looked like air filter fibers that wouild plug the screens just before the jets. I cleaned them all -4 - out and she has been running and purring every since. not counting electrical problems, I have just finish the last of tonight. soon as tonights snow melts down in the morning going for a ride.. just cause I live in spokane dont mean I cant ride all year. gona stud my tires this weekend . keep rining

I've been out of town and haven't had time to work on her yet. I just got the battery back to charge and she started right up, but not 2 minutes after start, she choked out again. Definitely think it has something to do with fuel lines/a definite carb clean. I promise no more posts until I'm done cleaning her up a little!

Make sure to seal everything from airbox/filters to exhaust tip - no air leaks.

Good luck.

while carbs are off? or in general?