stock 1981 kz550 - running lean lean lean

Motor Head wrote: What is the #'s on the Spark plugs? Correct heat range? NGK or?

It had an old set of NGK D8EA's in there and the grandson had bought a new set of four D8EA's and gave them to me when I bought it. (Sidestory of the grandson -- he had the engine running after buying a battery but the #3 cylinder was dead, when I went to buy it the #3 header was stone cold after a couple minutes of running, he was a big guy, I mean pro football linebacker sized dude, huge hands and he apparently sheered off the screw in the #3 carb that fixes the throttle slide arm to the shaft -- I found the head of the screw in the top of the #3 carb and had to drill out the remnant of the screw from the shaft that runs through all 4 carbs and lifts the slides. Big dude. He gave up on the bike because he didn't know carbs or mechanical stuff in general apparently. Real nice guy too. I suspect the carbs were stuck from setting and he just torqued the shit out of the throttle grip and 3 of the 4 carbs freed up and Junior snapped the #3 screw.)


I put the new NGK D8EA's that he gave me in there yesterday. I was thinking about going one colder yesterday after the knocking didn't go away, but that would be a band-aid, the manual calls for D8EA's in the bike. Gap is right at .6mm and the plug caps are on tight.

Motor Head wrote: Good luck getting those carb boots on and off, PITA! But they run good with the Airbox.
After install verify no Air Leaks at manifolds.

That is an understatment, pita. I removed the 2 screws on the sides of the stock airbox that bolt it to the frame and got some clearance by pulling the airbox back -- but it was still a battle of wits between a dumbole monkey and 4 rubber airbox boots.

This time I'm going to try something different -- don't know if it will work -- I'm going to drape my ratcheting tie-down nylon strap, which is 1" in width, across the front of the rubber airbox boots and pull them back by tightening the tiedown gradually.

Using a hair dryer can soften up stiff carb boots.

www.z1enterprises.com/detail.aspx?ID=331 :cheer:

Thanks dudes for the hair dryer and Z1 pointer there, may need those but for now...

I got suspicious of the vacuum-actuated petcock maybe having an effect on my fuel level check.
I.E. maybe the clear tube method is inaccurate because there's no fuel flowing into the bowl to replace the fuel that runs into my clear tube -- on the contrary, when I loosen the drain plug and the fuel runs up into my clear tube, that's actually creating a vacuum on the fuel line because the petcock is in the off position. (Think about bench testing the fuel level -- you don't cap off the end of the fuel line and then use the clear tube - you leave the end of the fuel line open, and thus on the bench, you don't have any vacuum due to a capped fuel line that might mess with the clear tube check.)

To overcome that, I put the petcock on 'prime' and watched the overflow tubes -- no gas came out, which told me the float needle valves are working, shutting gas flow when the float's at its limit.

THEN I repeated my clear tube check of each carb with the petcock open on 'Prime' and sure enough, I've got 3mm to 4mm fuel levels in all carbs. So the bike in lean due to something else.


I am starting to wonder if I have 2 problems. I discovered that the muffled knocking I hear at idle is controllable with the clutch.

I put the bike in neutral, motor running, bike idling, I hear the muffled knocking.

I pull in the clutch -- again, bike still in neutral -- the muffled knocking changes, gets quieter.

Sure the bike is running lean, but I may have mistaken the muffled knocking for pre-ignition and it might not be.

One of the things I found when I brought the bike home 1 week back was -- it was way overfilled with oil. I drained a fair bit until I could read a good oil level in the sight glass.

That's got me wondering and worrying -- maybe damage somewhere inside?

The reason that concern has me puzzled is -- this bike SCOOTS, man.
It is quick little monster. It can't be too messed up or it wouldn't pull so hard.

newOld_kz1000 wrote: Fixing the timing advancer pretty much took the bike from a skateboard to a Ferrari in terms of power. It really gets up and goes, except it stumbles immediately when I'm moving up from idle, I have to open the throttle more than I should but then it gets up and GOES. So the advancer was causing the poor power problem.

But the pinging did not go away. I'll put the old plugs back in, but I suspect there's something else going on. I did notice my fuel levels in all 4 carbs were a bit low when I checked them all about 1 1/2 hours ago, but I don't think a low fuel level in the bowls will make the plugs scary white and make it ping/pre-ignition/detonate.

Set your fuel levels to spec. That should fix the stumbling & may solve the lean issues otherwise as well.

:laugh: you dont have pre-ignition. Your timing is fine, and your carbs are floating properly (as you discovered with a proper prime on float level check :laugh: ).

From the sounds of it, your ignition is making nice spark and the plugs are getting nice and hot, as they should, hot enough to burn all the carbon trace off the tip is normal.
Look down into the plug were the base of the ceramic meets the metal. If there is so much as a whisp of carbon trace around the base, the carbs are jetted fine. You probly have a nice soot ring on the metal base of the plug threads... right

Play with your mixture screws, and check the advance mechanism with a good timing light to see the progression of advance.

Bone white plugs are not a bad thing, and are often actually still too rich for max power with a really good ignition. Brown tipped plugs are toooo rich, or weak ignition, and besides all that info is old hat, from back when they used leaded fuels.

PEACE.

TeK9iNe wrote: :laugh: you dont have pre-ignition. Your timing is fine, and your carbs are floating properly (as you discovered with a proper prime on float level check :laugh: ).

From the sounds of it, your ignition is making nice spark and the plugs are getting nice and hot, as they should, hot enough to burn all the carbon trace off the tip is normal.
Look down into the plug were the base of the ceramic meets the metal. If there is so much as a whisp of carbon trace around the base, the carbs are jetted fine. You probly have a nice soot ring on the metal base of the plug threads... right

Play with your mixture screws, and check the advance mechanism with a good timing light to see the progression of advance.

Bone white plugs are not a bad thing, and are often actually still too rich for max power with a really good ignition. Brown tipped plugs are toooo rich, or weak ignition, and besides all that info is old hat, from back when they used leaded fuels.

PEACE.

Thanks 9, I need some encouragement, this bike is like a hot Hooters gal you have lassoed, she is hot to trot but when you get her home she likes to chatter. Makes you wanna ride her all the time and tell her to keep it down....


Here are photos I just took of the 4 plugs:

PLUG #1



PLUG #2



PLUG #3



PLUG #4


I am pretty sure the muffled knocking is not pinging, although I could be wrong.

Today I replaced the crumbling sponge gasket on the air filter with window insulating stripping to get a very good seal between the air filter and its mating surface on the insides of the black plastic air box that the air filter installs into.

The bike rips hard. It shifts great.

I used my timing like and noted that the advancer unit is moving with the increase/decrease of the throttle. Again, you can't set timing on this bike -- it is electronic ignition with only a pickup coil plate and no adjustment is possible.

What could the muffled knocking be? The grandson overfilled it with oil and drove it around (with a dead #3 cylinder due to a broken throttle slide lifter) -- he drove it up and down his block before selling it.

Could the excess of oil broken something?
I did not find any oil at all in the bottom of the airbox where the crankcase vent hose (you'd think) would bubble up any overage of oil from the crankcase breather.

This bike has not been registered here in California for the road since 1987 -- it sat for a long time. Maybe the clutch is gummed up/plates stuck/other after all this time? That might explain the muffled knocking at idle?

Reason I know the bike was sitting-sitting-sitting was - the old brake fluid in the master cylinder had turned to a jelly-like goo.

Could something in the clutch be making a muffled knocking?

Where is the knocking coming from ?

What is the frequency ?

Does it change with rpm ?

What running problems are you still having ?

These arent the quietest motors, the primary chain will make a knocking noise at idle if the carbs arent synched just right and/or if the idle is too low

mjg15 wrote: Where is the knocking coming from ?

What is the frequency ?

Does it change with rpm ?

What running problems are you still having ?

These arent the quietest motors, the primary chain will make a knocking noise at idle if the carbs arent synched just right and/or if the idle is too low

It is around the area where the primary chain is, that's where the chunking is loudest.
And as the RPMs drop down to idle, man it gets louder and louder.

The chunking noise seems to fade as I rev off idle but then the regular engine and exhaust noise gets louder as I accelerate and drowns out everything else so I can't tell if the chunking is still there.

I tried today to find that out by parking the bike, running, at idle, with my helmet off, and holding my head down on the left side of the motor to listen -- chunk-chunk-chunk at idle then the volume of the knocking sounds drops as I gas it, but then the normal increase in exhaust and engine noise prevents me from being able to hear the anything else. ('blue on black,' 'tears on a river', etc.)


Here's what it sounds like. Think about when you start your Z1 or Kz900 or Kz1000 on a cold day.
You put it on choke, then take it off the choke a bit too quickly -- remember how the motor gets a real loud chunking noise as it sounds like it might stall out? That's what it sounds like.

I'm going to take some shots in the dark the next chance I get to work on her:

1) completely slacken the clutch cable

2) check and clean the 2 emissions reed valves that are on the valve cover above the exhaust valves

3) remove the starter motor, maybe the starter motor clutch is making all that noise

4) pull the clutch plates etc. out and see if anything becomes obvious there.


For steps 1, 2 and 3, I plan on starting the motor and seeing if there's any change
(bump start if for step (3)).

I'm at a loss here.

these bikes are pretty notorious for making cam chain noise after they get a few miles on them... especially at or near idle. Think that could be it? listen to see if it sounds like its coming from the top end. Just a thought