Engine surging when riding against the wind

The bike was a basket case when I got it, so I have no baseline. I rebuilt the carbs and Redline tuned them for me. I also have new rubber in front and behind the carbs.

There is supposed to be a plastic piece just in front of the air intake under the seat. It bolts to the frame just under the tank. This was put in place by Kawasaki to help prevent the condition you are getting. Is it missing?

Are you talking about the silencer? That piece is missing.

BTW, thanks for the reply Baldy.

The KZ650 came equipped with something called an:

- Air Cleaner Baffle Plate, P/N 11019-003.



Presumably, based on the name and position, Kawasaki had some air turbulence issues under the seat that affected the air flow into the air filter and the air box and they solved it with this feature.

The PO had lost this part but I got a replacement from a member here so I never had a chance to see this symptom.

Hope this helps. Best of success.

Mine's a bit different. Here's a bad scan from my manual:

I don't have the silencer.

How are your vent tubes routed?

Years ago, I tucked mine upwards and forwards under the tank. At higher speeds, the bike would hesitate and sputter, and then surge. I scratched my head many times and tried all kinds of things before I finally tried routing those vents downward.

Long shot, but thought I'd mention it.

So If my bike was running like crap in high winds, I can blame my pods? where can you find a stock airbox?

How are your vent tubes routed?

They're routed down and back. Not facing forward at all. I was hoping to get everything pieced back together today, and take a test spin, but I decided to occupy myself with an ignition coil install.