Carb shoots off vac cap and boggs

Hi new here I have a 1980 kz750 4 with the keihin carbs.bike ran ok but felt like carbs would get plugged once and a while.just cleaned them and got new oring kits put in.
Ok ,now I started it today for the first time and it started right up and idles fine .i let it warm up and when I give it throttle it boggs down . Also the plug on the 4th carb vac blows off and shoots a small flame if I give it throttle. Long post sorry but I'm coming up empty with my searches on here.thanks!I have a video just don't know how to post it

Would check #4 intake valve clearance.

Good Fortune!

Also air leaks.
Steve

Thanks I tried spraying some starting fluid into the air box and I can crack the throttle all the way as long as I spray.so I'm running super lean? Do fuel filters stop the flow on these c.v carbs?

Have you checked your valves?
Steve

Is your tank rust free, fuel filters clean, float bowl high in spec, primary secondary jets really clean and air screws set right.???

I tried spraying some starting fluid into the air box and I can crack the throttle all the way as long as I spray

Intake boots with out air leaks ? Carburetors synced?
A tight or zero gap intake / exhaust valve clearance can cause a spit back into the carburetor.
Ignition timing set right and spark plugs colors checked?
Pictures of your carburetor environment will help to solve your problem.

Michael

A fuel filter can stop the flow if it is clogged with dirt and rust from the tank or if it is a filter designed for a pressurized system.

If it is the correct filter and it is not clogged with junk frm a dirty tank, it will not stop the flow.

As previous posters have noted, you need to do basic maintenance like checking valve lash. Open the service manual to the roitine maintenance section, and perform all the maintenance items as listed. That way you can eliminate many potential problems and can more easily identify any remaining ones. If valve lash is incorrect and the carbs are not synchronized and the carb holders leak and some of the jets are clogged and the fuel levels are incorrect and the petcock is malfunctioning, taking a stab at fixing one of them will not get you where you want to be, and you may have wasted time and money "fixing" something that was not really a problem.

TexasKZ +++1

I have it not better describe as with your words. It is a basic maintenance for bikes that
has set over year with out of service and maintenance.

Michael

Fo sure, and there is no way to know if any of the maintenance was ever done.

It is so common for guys to jump to the carbs before they check the valves. They may get it running better but it will get worse and burned valves and lost $$$ will be the result. So many times a bike is sold and the PO said all it needed was the carbs cleaned when he was too lazy or cheap to do them.:whistle:
Steve

Wanna say I really appreciate all the help ,I'm gonna start going through all the maintenance. I knew when I bought a 37 year old bike I basically would have to go through the whole thing.gonna order a valve cover gasket and take a peek under when I get it

I'm getting spark and fuel but not sure about my timing. Everything us pubes up and free but not sure if it's working right the f lines up when the cam hits the left pickup.dont have a timing light yet just seeing if this looks right to yall.also I found a pink connector not sur3 what it's for is it important? s518.photobucket.com/user/ia-turtleboy/m....mp4.html?sort=3&o=0 [img ][URL=http://s518.photobucket.com/user/ia-turtleboy/media/20170531_154607_zpsalyuyugd.jpg.html][IMG]http://i518.photobucket.com/albums/u344/ia-turtleboy/20170531_154607_zpsalyuyugd.jpg[/img] [/img][/url]