Engine Stalls When Opening Throttle

Hello Everyone,

1977 KZ650C here.
I have solved a previous electrical issue where the bike would not idle without the headlights being on by cleaning the grounds, thank you for the responses.
Now that the bike idles, I am encountering the issue of the bike dying when I open the throttle. I am running 112.5 main jets with a 20 pilot. These are the original jets used when the bike last ran. Carbs are all clean of debris and gaskets/rings have been replaced. The air screw is set at 1.5 turns out from lightly seated. The spark plugs are carbon fouled upon removal.
I have not changed any of the setup since it ran before I got it out of the family garage after sitting for a VERY long time. I attached a couple videos for reference so you can hear what I am experiencing. Where do you suggest I start in my attempt to fix the issue? I am happy to answer any questions to assist in diagnosis.

Thank you! 

I work on both car and motorcycle, but when you open the throttle and dies, that means the mixture is too lean.Take the pods off, block half the openings with cardboard or something long and solid so it won't be sucked into carb openings, then try again and see if it revs up. Even a little, if it gets better, you found the problem. If not, look somewhere else.

I have 89' ZX-7 and when I took the airbox out and just ran the carb without anything, not even pod filter (wasn't available at the time. I tried this when I bought the bike new and I couldn't find any aftermarket parts as it was too new), engine would not rev past 4k and just dies right after. put the airbox back on and I had no problem. I wanted to get some bigger jets, but even that wasn't available, at least not on the island I live on.

wrote:

The spark plugs are carbon fouled upon removal.

 

[I can't watch the videos right now, so apologies if any of this is covered.]

This is a serious question: what do the plugs smell like? Gas or oil?

If the bike has been sitting for "a VERY long time" it is possible the valve guide seals have hardened and are no longer sealing, allowing oil into the combustion chamber. Oil burns poorly and will cause a sooty appearance on the plugs.

If you're seeing black smoke from the exhaust, the fuel mixture is too rich; this is unlikely with pods as Ojisan braddah pointed out. If you're seeing light blue smoke from the exhaust, the engine is burning oil.

Some cheap pot filter block the air intake ports of the fuel or idle air mixture circuit!

 

Sounds like you have some fuel delivery issues and should check that there's an unrestricted supply from the tap, clear fuel filter, no kinked hoses and that the carb jets and passages really are free from blockages.
Regardless of any other issue you may have you need air corrector jets and good quailty filters such as K&N, APE, Ram Air etc ( not cheap chinese Emgo or Hi level, DNA etc which cause more issues than they solve) to cure the off idle flat spot.
All other carb setting remain stock apart from fitting larger mains by a couple of sizes.
Air corrector jet kit.Kawasaki Z1,Z650,Z900,Z1000,Z1R.MK2, MIKUNI.LEDAR.PODS.K&N | eBay

The #20 pilot sounds a little rich.... Not saying to change it out yet but Pretty much everyone runs 17.5s but I feel like Zed says it might need a deep cleaning of the passages 1st.

Also guys does his air screw look right? Mine are about level with the top surface of the carb (2 sets) at one and a quarter to one and half out. If I'm remembering right almost everyone's are about there to ??

Thank you everyone for the responses. I am going to start from the top with suggestions:
I took the pods off and yes, I am able to slightly apply more throttle before it dies.
Nerdy, the valves were re-done at the shop as the timing was off and caused them to bend (the shop unfortunately had to close down since). Fingers crossed that oil getting into the plugs is not the issue. No blue smoke has been noticed.
I am going to order those air corrector jets as well, I did not know those were needed as the way the bike sits, is the way it ran before put in storage.
I welcome a link to your suggested pod filters (brands were mentioned, but I would like to see exactly what you are successfully using).
As far as fuel delivery, everything seems good. No restrictions are seen, do you suggest getting an external fuel filter between the gravity fed petcock and carb? It did not have one before so I just replaced the gas line. The petcock is clean as gas is freely and steadily flowing from the tank with the small screens attached to the petcock (in the tank at the top of the petcock fuel inlets) still intact.
I am able to blow air through each carb passage. I have cleaned them - soaked in carb cleaner (excluding rubber pieces) and ran air through them. Is there anywhere that is more prone to blockage? The mains, pilots, jet needle passage, float bowl passages are all free and clear.

I can provide any additional pictures if requested.

 

When it comes to passages within the carb body. Just blowing air through doesn’t mean all passages are clear. You will need to track every passage and block all exits on that passage. Use carb or brake clean, shoot it through a passage at its longes run. Blocking all exits between the start and the end. Then plug the end (furthest) and open the next furthest to the start of that passage. Working your way back till you shooting cleaner in at the exit and it is now coming out at the beginning. It’s the only way to know 100% all are clear. It’s time consuming but the only procedure that works. I use tapered cones for blocking off threads and holes when powder coating. I have different sizes gun drilled so the cleaner straw can be placed inside the cone and then fit into the carb passage. Just another way to ensure your getting your carbs clean. 

 

 

www.kzrider.com/forum/3-carburetor/59856...r-in-cv-carbs#844790