KZ550, capped valve cover, won’t start

1981 KZ550
pod filters(larger oval shape), pilot jets drilled to .0145, main jets to 1.00, needle raised two positions, air screws around 1-1/4(but also tried between 1&2 whole) turns out.
closed vacuum lines to boots between carbs and engine.
runs with idle screw completely out, some deceleration popping.
PROBLEM:
shuts down and won’t start when valve cover vents are closed, or if i block the large opening on back of valve or if i leave open small opening on valve.
RPM’s do go up a bit when choke is on even with engine warm. choke on allows engine to just barely run with valve cover capped.
QUESTIONS:
am i running too lean? how much?
what should i adjust first?

cheers!

Carb holders may be leaking / valves too tight.
Steve

SWest wrote: Carb holders may be leaking / valves too tight.
Steve

bike has 14,921miles.
was totally stock unmodified, but sat for about 8years.
could the valves be maladjusted with that low a mileage?
there is in fact minor fuel seepage where the carb holders attatch to engine. would that really cause such a major side effect?

The valve cover ports are not vents, they are routed to the exhaust ports but have a flapper check valve under the small covers.
They should not affect engine running at all. If they do, then they are probably leaking air into the intake.
To me, you have the needle set too rich for off-idle running. The leaking air system is probably allowing the bike to run, but when you close them off, the bike gets choked again.

To properly tune the bike, you should first check the valves (read the warning in my signature before touching the valve cover). I have several factory manuals linked in my signature as well. Get all of them.

When the air system is malfunctioning and leaking, it causes popping and backfires on deceleration.
You can remove the vacuum switch assembly, and then cap off the valve cover ports and cap off all four of the intake manifold ports. The petcock has a dedicated port on the #4 carb.

With pods on a standard Kz, you can sometimes get away with just a small shim on the needles and all stock jets. But if you have a performance exhaust, you might need to up-jet a little from there. There is a tk22 website in my links which shows the proper way to shim tk22 needles.
s3.amazonaws.com/gpzweb/TK22mainPage/TK22mainPage.html

Do a compression test after you know the valves are set properly.
Then make sure the ignition timing is set correctly along with the advance curve.

After all of that (including looking for vacuum leaks like others mentioned) then you are ready to start doing some jetting.

axel wrote:

SWest wrote: Carb holders may be leaking / valves too tight.
Steve

bike has 14,921miles.
was totally stock unmodified, but sat for about 8years.
could the valves be maladjusted with that low a mileage?
there is in fact minor fuel seepage where the carb holders attatch to engine. would that really cause such a major side effect?

Yes. They should be adjusted every 5000 or less miles. Chances are they have never been touched. Leakage at the head suggest hard and leaking carb holders as well as fuel getting into the engine. I was hoping Loud would chime in. Follow his directions, you'll be glad you did. Hopefully you didn't drill out those jets too much. They can be hard to get. The 550 I picked up the pilots were so clogged I had to use my smallest jet drill to clear them. It worked out so it wasn't as cold blooded as it was stock and the pilot mixture screws were able to compensate for the larger jet sizes. Pics are always helpful as you go through the processes.
Steve
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882

loudhvx wrote: The valve cover ports are not vents, they are routed to the exhaust ports but have a flapper check valve under the small covers.
They should not affect engine running at all. If they do, then they are probably leaking air into the intake.
To me, you have the needle set too rich for off-idle running. The leaking air system is probably allowing the bike to run, but when you close them off, the bike gets choked again.

To properly tune the bike, you should first check the valves (read the warning in my signature before touching the valve cover). I have several factory manuals linked in my signature as well. Get all of them.

When the air system is malfunctioning and leaking, it causes popping and backfires on deceleration.
You can remove the vacuum switch assembly, and then cap off the valve cover ports and cap off all four of the intake manifold ports. The petcock has a dedicated port on the #4 carb.

With pods on a standard Kz, you can sometimes get away with just a small shim on the needles and all stock jets. But if you have a performance exhaust, you might need to up-jet a little from there. There is a tk22 website in my links which shows the proper way to shim tk22 needles.
s3.amazonaws.com/gpzweb/TK22mainPage/TK22mainPage.html

Do a compression test after you know the valves are set properly.
Then make sure the ignition timing is set correctly along with the advance curve.

After all of that (including looking for vacuum leaks like others mentioned) then you are ready to start doing some jetting.

Thanks for the detailed list loundhvx!
I plan to follow your directions as soon as I have some time again.

However, for now the bike seems to be running ok. After my last post I messed around a bit more.
with the engine cold I started it and sprayed some starter fluid around the carb holders that showed seepage. the starter fluid had no effect on RPM's.
I messed around some more with covering the vent that normally would go to the air box while adjusting the air screw. previously I must have had the engine flooded because at two turns out the engine wouldn't start.
Now with the air screws 2-1/8 turns out and the PCV vents all sealed the engine runs great! RPM's drop immediately upon releasing throttle and there is no more popping.
I'm still planning to do the valve clearance and other maintenance soon. I'll make sure to look at all your associated documents loudhvx.
thanks!

Also check the choke flaps. There is a page on the tk22 site that shows what to look for. If they are damaged, that can make for harder starting as well.

loudhvx wrote: Also check the choke flaps. There is a page on the tk22 site that shows what to look for. If they are damaged, that can make for harder starting as well.

yes i checked those when i rebuilt the carbs, found an old post of yours about them. one was ok but the other three had the pins partway out, one of which had a partially broken hinge. i cleaned it with acetone and very precisely JB-welded it, made sure it has full range of motion, should be stronger than the originals. also pressed the sides of the pin holes for each flap to keep the pins in place better than before. they must be working great, the engine seems to start before i even hear the starter lol!

Nice!