New member. '80 KZ1000 w/ fighter-cafe aspirations

Bought it at a yardsale for $200 and it came with a '75 KZ900 parts bike thats rough its been sitting for about 10 years..has a Kerker 4-1. So far i've rebuilt the carbs on the bike.. I got the bike to start but it runs rough..

not sure if I should ask my questions here or go to a different section? since I don't know if its a carb or engine or ignition problem..but anyway heres a pic i took while working on it.. thanks for any help, guys.

First off, welcome and nice score on the bike.

Start up a build thread in "Projects" and post your work and questions there. If it goes too long unanswered you can ask again under a specific category.

I would make sure the gas tank is clean and the petcock then install an inline filter on gas line & reclean carbs again.Might want to check grounds on the frame and the coils might be lose.When I get an old bike I start at the tank and work my way down . Then do a compression test to see what I have to work with. Are you getting a good fat spark at the plugs.

Also, they run like crap with a dead battery.

Thanks kid, peter, damarble i'll probably start a project thread.

Well, the fuel tank was pretty clean, it filled it up with mineral spirits and nuts and washers and shook it about, drained it. took apart the petcock, cleaned it, replaced oring.
Full on rebuild on the carbs,

they had 102 main jets..the kit i bought came with new 102.5 and 105 so i put the 102.5s in since i figured it has a kerker 4-1 and no air filters at the moment. it had .015 pilots and the kits came with those i put them in, new needle and seat, choke o rings, air screws adjusted 1.5 turns out.

Float level isn't consistent between all of them but i think i'm going to make them higher..

I have ok spark..its strong enough to hear but i think the 30 year old coils and wires look like they could use a break..compression numbers worry me alittle..now remember the bike has been sitting for 10 years or so..20,000 miles on it, modified. so valve clearance is probably out of whack i'm guessing. and the motor was cold and i have ran it maybe a total of 5 minutes so far

Cylinder 1 2 3 4
135 125 120 110
... please tell me its not a loosing battle with numbers like that..

I plan on doing some sort of homemade mercury manometer balance and i have an IR thermometer as soon as i get it to idle consistenly..you puull the choke up and it revs up and sounds decent..but at idle it sounds like its loosing a cylinder and backfires through the the #2 carb

If you try to open the throttle it kinda..seems like it falls on its face unless you do it slow, and even then it seems sluggish and backfires, lot of black/brownish smoke coming out of the exhaust.. since then i've taken the carbs off and done my best to set the slide level as even as possible between the 4..there were a few that were off by enough to notice. I also cleaned and spray lubed the ign. advance mechanism.

so..thoughts / ideas on the compressions numbers? thanks for the warm welcome, guys

The main issue with the compression is the difference between the highest and lowest cylinders. They should not vary more than 14.5 PSI. But, as you said, the bike has been sitting for ten years.First check the valve clearance and make sure they are not off. You may need to re-shim any out spec ones. Next, the rings may need unsticking. Squirt a 2 or 3 oz of Marvel Mystery Oil down each spark plug hole. Don't disturb the engine and let the oil soak the rings for a few days. This will give you a chance to sort out the carbs if they still need cleaning in any of the pilot circuits. Patton has diagram here somewhere on how to clean the pilots circuits out. After a few days of soaking you can start her up and see how she's running. I would put at least a 100 miles on her before rechecking the compression. This will give them time for rings to re-seat. Myself, I also ran seafoam in the oil for about 20 to 30 mi as per instructions. When all was said and done, all my cylinders came out even from from an original 16 PSI variance. Not high, but at least even, lol.

Thanks, kz joe..you've given me some hope. They may not be even or perfect without a rebuild but if i can get them within an acceptable range i'll be happy. Now..is my kz a shim under bucket like a honda? and you think i scrounge shims from a '75 KZ900? Thanks for the help guys.

it is shim over bucket.

hopefully with some lube and maybe a lil run time the rings will free up and the compression numbers will come into line.

it takes 75 pounds of compression to create combustion.

100lbs is worn out.

leon

Well, after leveling the slides, adjusting float level way up, airscrews only 1/2 a turn out i poured some oil down the cylinders and i got impatient..as soon as i touched the starter it fired up..and to my amazement when i hit the throttle it revved up nice and quickly..i wouldn't say smooth but a major improvement over what it was..however i did only run it a few minutes, poured some MM oil in the cylinders..now it can sit a few days. i'll make a build thread the next time i update hopefully with some fresh parts. Thanks for the help again

Can you post some pictures of the 75 Please

The '75 is all the way on the left..i can get more pics if interested??

ADKBurntrubber87 wrote:

The '75 is all the way on the left..i can get more pics if interested??

Wow! Some people need their bike owners card revoked....and to be bitch slapped. What a shame.

Where are you located? Paperwork for the 75?