Surging under acceleration/steady load

[crusty1500]

Hello all!

First post on the forum, just wanted to introduce the bike and myself. First this is my first wing of any era, I've always wanted one and found this one at the right price. It's sat for roughly 20 years (last registration was 2004) and I bout it running but not quite road worthy. Changed the timing belts and coolant, new plugs, cruise and sub air filters replaced, cleaned the K&N it came with, new front and rear rubber and all three master cylinders rebuilt. When I first got it she ran rough. I pulled the carbs, rebuilt them and replaced several vacuum lines that were questionable (both 90s under the black mat, several other smaller lines, line to the petcock), rebuilt the petcock, and checked the vacuum lines on top and they seem fine. Issue I'm having is she idles perfectly smooth, but under a load it seems lean and has a surge. Under an acceleration it's much smoother, but steady load it's worse. I've read about the coolant temp sensor for the ECU and am debating it, but I wonder if there's something else I'm missing. Any thoughts are much appreciated!

[crusty1500]

Few additional things: checked spark on both banks and checked compression. Bike has 150 psi on all 6 and good spark. Checked inside the carbs while running and I can see fuel being drawn out, so I must be missing something. Plan on doing a seafoam treatment first for a few tanks before ripping the carbs back out.

[bbrackett]

I had an issue like that, it felt like someone was turning on and off the ignition, didn't feel like a fuel issue
What I found when I replaced my belts, was magnetic crap on the Ignition pickup coil/sensors.. I cleaned that stuff off.. and that issue went away !!
so.. if you didn't clean your Ignition pickup coil/sensors you may want to do that..

ps.. when I replaced my belts, I only removed the Right Side Engine Protection Bar
took the center inspection cover off
and I was able to slide both covers off WITHOUT removing the Coolant Hose !!

Could be fuel bowl level or dirty mains or a vacuum leak going to the sliders

on my Ignition Module, I also found the vacuum line plugged on the module side !!..

You may want to get a dual carb Vacuum Gauge kit and check stuff further, maybe while riding.. (carefully)

[crusty1500]

It doesn't feel like an ignition cut, more like you're rolling off and on the throttle smoothly. When I changed the vacuum lines it has started to run better, and the more I run it the better it gets. I have set the fuel sync while hot and I'm running some seafoam through the fuel as well. The pickup coils were clean when I changed the belts, no junk on them at all. The more I research the more it seems like that coolant temp sensor is more an issue on the 90+ models but I could be mistaken. As far as taking the sync tool on a ride, I might just do that tomorrow and see what it's doing under load. Also, with the air filter off you can blip the throttle and both slides move so I don't think that's an issue. They also don't stick at any point in the bore.

[crusty1500]

Also, float levels might need to be checked. I did briefly when the carbs were off but it wasn't measured of anything.

[crusty1500]

Btw here's a pic of the old girl.