79 kz650 loss of power

The spring that wraps around the air duct at the carb is enough to seal it. Ed

My airbox boots are just barely on. Like they shrunk a bit or something. The spring seems like it's not really doing much

When you checked the carbs did you check your jet sizes? It seems unlikley that they were changed if everything else is standard but often the problem can be found in things you take for granted. (did I just sound like Yoda there?Or Grasshopper??)

No I did not. I assumed they are original. I'm going to tear them down tonight and check everything again. What should the jet sizes be? Assuming they are original?

97.5 is what the main jets say

All jets clean accel pump working. I'm at a loss here

bikerdave79 wrote: No I did not. I assumed they are original. I'm going to tear them down tonight and check everything again. What should the jet sizes be? Assuming they are original?

First determine if you have air screws or pilot screw (or unlikely - both). Then take a look at the charts below. ed

Try adjusting the accelerator pump. Look closely at the diaphragm to be sure it's not cracked or has a hole in it. Check balls too. The carbs are set up lean and the pump makes up the difference. If there is a leak, when you back off, fuel is sucked into the intake causing a over rich condition and back fire. I'd check both diaphragms on the bottom of the carbs.
Steve

It fixed!!! After removing the carbs entirely, going over them, checking jets, float levels, pump diaphragms the carbs looked to be in excellent shape. Upon putting them back in I decided to smoke the airbox with an evap smoke machine for cars. Well I found out the lid that holds the filter In was cracked. And that cyl 2-3 intake boots were heavily leaking. after taping up the culprit so that everything is air tight... She hits on all four and runs like the wind. So I guess that little bit of air creeping past was enough vacuum loss to cause a problem. Yikes. Just an fyi if anyone else is having trouble with this type of thing.

And PS those spring type clamps are junk. I replaced with actual band clamps. Big difference

Interesting. My airbox ducts fit so tight on the carbs the springs aren't really necessary even though I always use them. Did you find the ducts to be a tight fit on the carbs? I wonder if they had been replaced at some point with something a little larger size? Ed

Your bike looks to be in WAYYY better shape. Lot more oxidation on my engine parts, rust, airbox boots are all stiff and hard and take much effort to even get them halfway on. NY bike that spent most off seasons outdoors so I'm sure that didn't help.