Timing advance issues?

So Ibeas riding today and everything was working great when all of a sudden, my bike started running poorly above about 3500-4000 rpms. Felt like it wasn't getting fuel or something. However, it would only happen in gear. In neutral it revs up normally. Can this be from the timing not advancing?

I did pull the plugs and it seemed it was running lean. I'm running pod filters and bigger mains and pilots. I've been riding it for awhile like that and have checked the plugs periodically be to make sure it wasn't running rich or clean. They've always been a light brownish color until I checked them just now.

The bike is a 78 kz650

The timing advance mechanism is under the right side engine cover. Easy enough to pull the cover and have a look. There is no oil under that cover and you can run the engine with it off. That said the advance mechanism is connected directly to the crank shaft so it works the same if your in gear or out.

Flooding can feel like you are running out of gas. But you said the plugs looked lean so that seems doubtful. Put your petcock on prime and let it sit to see if it is still flooding. After waiting about a half hour if there is a puddle of gas under your bike, you're flooding.

Are you sure you were not running out of gas? Plugged fuel filter? You can always pull the fuel line and attach a longer hose to a gas can. Turn your petcock to prime. fuel should run freely. If your floats are full your bike will run for a bit. Put the petcock on run, start the engine, and see if fuel is running freely into a gas can. I'm assuming you have a vacuum petcock.

Remember that you are playing with gasoline. Have a fire extinguisher at hand and don't start yourself on fire.

Honestly, I'm not sure if it's a vacuum petcock. Fuel flows from the tank no matter what position it's on. Prime, reserve, or ON. I'm pretty sure there's a diaphragm in it and I'm assuming it doesn't work correctly? Definitely have fuel though. The carbs are full. I did notice a little gas coming out of the 3rd carb overflow tube earlier today though. But it stopped and my bike ran fine. I'm thinking leaky valve needle?

If you use any gas with Ethanol in it, the fuel system may be damaged. Some gas stations list it on the pumps, other, not so much. Floats made of brass or plastic may fail, the rubber tipped carb needle valve may soften, and fuel lines may internally swell, restricting the fuel flow.

The carbs were as clean as could be 2 weeks ago. coukd ethanol cause them to clog that quickly? And if it was a carb issue, why would it rev fine in neutral but not under load?

I checked the timing advancer and everything checks out so its def not that. Gotta be a carb issue right.

Do you have points? Are they sparking? Are they or one of them loose?
Steve

If the petcock is marked On, Res, Prime, and fuel flows in any of those positions with the engine off, then it is a vacuum petcock that has failed. Fuel coming out of a carb overflow when the engine is off is a sign that the needle valve in that carb is also in trouble . The combination can cause intermittent flooding in that carb.

Ethanol also attacks the rubber diaphragm of the vacuum operated petcocks.

Ok yeah, I thought that the petcock was fucked. Guess a rebuild kit is in order

And yeah, I'm running points. They are sparking just a tiny bit though. I know the condenser is supposed to keep them from arching. Is it normal to see alittle spark though?

Still not sure why it'd rev normally in neutral but not while in gear.