kz 1100 died on hwy.

I was test riding an 83 kz 1100 ltd for the first time today after buying and working on it. I had the battery on
a 2 amp float charger all winter indoors, so it was fully charged. The fuel tank was half full. I rebuilt the carbs to spec. Set the floats ( upside down ) to the recommended heights with a gauge. I swapped the valve shims around, so the vaves had the correct clearances.
I primed the carbs and It started right up ( slight slapping sound ) I pushed the choke in as it warmed up and
adjusted the idle so it was even, Being unsure of the tank capacity, I had the petcock set on reserve. I cruised
about 20 miles on a back road at 60 mph. When I entered the intersate I accelerated to 75-80 mph. After ten miles it slowly started to die as if it were out of gas. With plenty of gas I tried to start it again without luck.
I got it home ( yay AAA tow truck) and it started right up again and still had a gallon of gas in it. Any ideas ?

 

gas tank vent?

 

+1
Sounds like the fuel flow stopped becuse of a plugged vent.

 

I had to reline that tank with an epoxy due to pinhole leaks where is the vent ? part of the cap ?
Also is slapping sound a broken ring or a piston with a hole ? Will do a compression test today.

 

from the four carb holders are four vacuum nipples #1+#4 have tubes that tee into a single tube to
the CAS/silencer under the front of the tank, #2 is capped, #3 operates the petcock. There is a drain
tube from the small tray under the fuel sending unit. Is there another tube I'm missing,or is the cap itself the vent ?

 

the vent is in the gas cap, the slapping sound might be the cam chain
these people know kz's http://kzrider.com/

 

The slapping sound could also be piston slap. Does it go away as the engine warms up?
It could also be caused by the carbs not being synchronized.

 

What is piston slap ? I've got all the tools I need, plenty of time and patience.
Also if the tank vent is in the cap, can a clogged vent be fixed by soaking
the cap in carb cleaner ? ( brain fart!!) would the slap be cause by uneven
vacuum from cylinder to cylinder ?

 

Piston slap is caused by excessive clearance between the piston rings and the cylinder wall. If the sound goes away as the engine warms up you can just get in the habit of letting the enigne warm up at idle, and ignore the problem until it's present when the engine is warm.

Uneven vacuum (carbs not being synchronzed) will cause a similar sound; and as Polock mentioned, so can a slack cam chain tensioner.

 

I did a compression test yesterday. I got +- 120 on every cylinder but #3 that one was 60 ft. lbs. The bike sat for
several years before I bought it. I was thinking that before I tear the engine apart and redo the head, cylinders,pistons,
rings etc.; I should squirt an atf/acetone mix into that cylinder (four squirts from an oil can into the plug hole) and let
it sit for a few days while I work on my xj750 project and maybe the rings might loosen up. Also, I checked the gas cap
and it seemed ok. I cleaned it again for good measure but I think the engine quitting might be a float level problem since it quit
on an uphill stretch of interstate after 15 miles at 75-80 mph.

 

could be the vacuum line to the petcock collapsing, shutting off the fuel.

 

The tubing is new clear vinyl tubing, it's pretty stiff. I had to heat it a little with a dry heat gun to get it to stretch over the vacuum port.
I had the cam cover off to swap valve shims before I ran it. The chain was ok then. I set the carb floats to the recommended height
off the carb bottom (upside down) but didn't do a wet test. Maybe it stalled because the fuel level in the float bowls was too low.
80 mph on a grade drained the bowls. It started up when the bowls filled again. I shot a few pumps of atf,acetone,marvel mystery oil
into the #3 cylinder hoping the low compression was a ring partially stuck in a piston groove.

 

It's collapsing when it gets hot. You need to buy real vacuum line, which is not made of vinyl, not see-through, not any more expensive, and won't collapse.

 

on a xj, i don't think i could tell the tightness of the cam chain by checking with the valve cover off. a kawasaki may be different .....?

 

I will check and see if there is any actual vacuum line in Santa fe. Last summer I asked a local repair shop owner what he uses and he said "windshield washer line"
I'll get online and see what I can find.

 

Any auto parts store will have it in stock. If I can get it in Dodge, you can get it in Santa Fe.

 

I found that I had put the split shims on the headers backwards. I reversed them and installed new exhaust gaskets. That was the slapping noise.
The petcock had a bad "0" ring I think that's why it quit. I rebuilt it,now it's fine. Also, I wet set the float level and synched the carbs and it
runs pretty well for a 34 year old shed find with 35,000 miles on it.

 

Good show! Seems like your repair expertise level is growing expotentionally! Hopefull the compression came up on all the cylinders once you rode it for awhile and any stuck rings lossened up. Did you ever get your new tachometer?