81' KZ1000LTD no compression

Hey guys, its been a while and ive been broadening my horizons since I last posted on here. I own like 6 cars now and I added a 77' GL1000K to the collection of bikes but that's beside the point lol. My buddy bought an 81' KZ1000LTD from me. (no not MY kz1000 that ive posted so much about before.. that's a keeper). I picked this thing up for 700 bucks in Onawa Iowa. Just needed some stuff in the back put back together and an igniter box. After I got it going, I rode it for a few weeks and sold it to my friend so he had something to ride for the summer. It had leaky cam end caps and he never got it fixed. I didn't know so much oil could ever come out of an engine. I didn't see the bike for a while and then he got ahold of me to go for a spin randomly one night. that's when I saw how bad the oil leak had gotten. He insisted on riding in front which left me in the back getting fogged with 10w40 the whole time :whistle: He rode the bike like this for the remainder of the summer and I started hearing rumors that he blew it up. I finally got ahold of him to work on it and we got it over to the garage. I went through the carbs first. Then checked for spark (he wired his coil up to the positive on the batt and it just sat there energized until the batt. went dead.) All was good until we put fuel to it and started rolling it over. It wouldn't start and after a compression test we found it was less then 30psi across all 4. Checked timing before ripping the heads off. it was dead on according to my Clymer. Found the cam bearings were smeared a little bit. Inspected all 4 pistons. Just minor scoring on the front and back sides of each. No broken rings. The cylinders don't even look bad.... Im trying to figure out where the death came from. The valve shims have some heat marks on them(like too tight) but only on 1 or 2 of the cylinders. which would make sense if only 2 were dead but All 4 were dead. I guess my question is how touchy are these engines? Would minor scoring that I can barely even feel with my fingernail cause such a large loss of compression? Either way the cylinders/head are down at the machine shop. Also wanted to know if anyone used NPR piston rings? I hear good stuff from the automotive world about them. not sure about old jap bikes though.

Thanks in advance and its good to be back guys,
KT

Did you think to check the cam shim gap before tearing it apart?
It sounds more like all four cylinders have a bent valve(s) from neglect, rev ABUSE or massive overheat from no oil?.

Yes a valve clearance check would have been in order. Next you need to berate your buddy for not fixing a simple oil leak.

One option now would be to reinstall the head, assure each valve has at least some clearance, and perform a leakdown test, which should help diagnose exiting general condition of the engine top end.

Can perform a poor man's leak down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air.

May alternatively use a portable compressed air tank.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).
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Another option while disassembled would be using a bore gauge and micrometer to determine whether bores and pistons are within spec, as described in the FSM.

Good Fortune!

Now that's it is apart, it's a good time to install new valve guide seals and check if the guides are too loose by rocking the valves. Your manual will describe how to do this. Also check the condition of the valves and seats.
Admonishing someone that runs leaks that bad does no good. I prefer to not say anything not because it will hurt his feelings or teach him something, it's so I don't get a gut ache dealing with stupid. :whistle:
Steve


Viton seals. One of our members sells them.

You are probably right about telling some one they are not right in the head is a waste of time. I was looking at it from a safety stand point with oil getting on the rear tire. I have a friend who I helped service his forks with oil only to discover his seals leaked the ooil right out. He kept riding it with no fork oil.......Made a heck of a mess. He ws riding a Yam 650 twin.

Heat marks on the shims could be from the clearance going away and the valves hanging open and cooking.

Hope you checked the valve clearances before pulling off the head. Neglecting the valves is (sadly) extremely common and doing so results in poor compression and damage to the parts.

Kitten Tooth wrote: . . . 81' KZ1000LTD . . . the cylinders/head are down at the machine shop. . . .

For what?

Good Fortune!

May need new valve guides. definitely a valve job. you can test the guides quick. Pull the valve out, light coat oil, stick back in the guide, cover the top of the guide with your finger. Pull the valve through fast. No sound, replace, slight suck it's got some life, if it pops like a champagne bottle you can rule that out. Still do the valve job. Since you're in there may was well bust out the grinder and do some clean up work. 2/10ths right there.

Im still kicking myself for not checking the clearances before tearing it apart. We were going to do a leak down test as well but i figured he just roached it. I forgot to mention there was almost NO oil in it when we started on it that night. Im almost positive it had tight valves because all the lobes have dark marks too just like the shims did. Ill work on getting some pics of the pistons at least so you guys can see the scoring on those. I pulled the pan off the motor too and found metal paste in the bottom of the pan. Maybe this was concept model that was self machining? I had a feeling i was getting ahead of myself when i started cracking them nuts loose on top of the head. I think i was due for a freshening up though. All the cam bearings were smeared too. As soon as the machine shop is done with the heads hes gonna start ordering parts. Ill see if i can get those Viton seals in there. ill probably use them on mine too when i do my rebuild. My poor old KZ has been collecting dust in the garage for over a year now :whistle:

missionkz wrote: Did you think to check the cam shim gap before tearing it apart?
It sounds more like all four cylinders have a bent valve(s) from neglect, rev ABUSE or massive overheat from no oil?.

Im almost positive he did all of these things. He kept bragging about how fast he could get it going and sustaining those high speeds as well. This engine wound up to almost redline for 5-10 minutes straight probably made it do some colorful stuff... especially when it was low on oil. He claims he had it up to 150 last year when it would still start. Mine was touching redline at 135 so maybe hes full of it. Though his gearing is different then mine because we changed the sprockets last year using a chart i found on here. i know its a 16 in the front. not sure about the back lol

One more thing, Ive been giving this guy s*** constantly since we started working on it... just so everyone knows hahaha