TOPIC:

Hello folks.

I have been dreading penning this to paper for about two weeks.

Here is the background on the bike: 1976 kz900 which I have owned for 8 years and put 15k plus miles on. Bike has 46k total. Last year I pulled the engine and painted the frame, re wired a lot of the bike and freshend up the top end (1015cc kit, new cam chain idlers & guides, and valve job by PSP). Dropped the oil pan to clean all the sludge out and clean the screen. Everything looked fine. I did not split the cases - hence original cam chain, didn't weld the crank, etc. I pretty much ran out of time and did not want to go any further. With the addition of a Jardine exhaust, Lester mags with dual disc Z1 front end, custom handlebars and everything either painted fresh or powder coated it was as close to a ground up job as I wanted to do. Bike is running stock cams and carbs(vm26) and Dyna S ignition with Dyna coils. I am really proud of my bike. I did pretty much everything except the head work, boring of the cylinders, and powder coating. It was a mix of work for 'show' and for 'go'

I have about 600 miles on the bike since I put it together earlier this year. I followed the break in procedures to the letter and was gentle for the first 100 miles or so. I'm not going to say the bike ran perfect because it didn't - slight midrange hesitation and an occasional backfire (blew #1 & 2 vacuum plugs off once) as well as an intermittent oil light / oil pressure problem experienced by many. There is an oil cooler and an analog pressure gauge in place - the few times the pressure would drop I would pull off and let it cool and everything would be fine. I had feedback suggesting this could be due to the oil cooler and to run a heavier weight oil. Every time the bike started I had good pressure which would lower as it warmed up.
I know that the mid range hesitation and other hiccups were warranting some carburetor tuning and maybe a timing adjustment but I had not gotten around to it yet. I had rejetted the carburetor for the air filters / exhaust before the engine work and it ran pretty well and I balanced the carbs using my Carbtune.
I would like to say also that upon the first startup after putting everything back together it was like night and day compared to how it was before. Carbs really easy to balance, consistent header temps, etc. I was meticulous when assembling the engine and I am confident that the quality of work done for the valve job / overboring was good.

Anyway, took the bike on a 200 mile ride three weeks ago. 100 miles to my destination, and 100 back. I'm not going to kid myself or anyone else - I was riding pretty fast for most of the ride home. Traffic was getting worse and I was hauling ass. About 10 miles away from home I pulled off on my exit.... bike died. Would not start. I was still getting power to everything. e I pushed it to a gas station and thankfully someone gave me a ride! Must've been karma as I had given a couple bucks to a homeless dude at one of my gas stops.

SO, I returned the next day with some tools - here is what I found: I was getting spark on all cylinders. It did appear to be a weak spark. Only getting 9v to the coils. Getting fuel. The mechanical ignition advance is not stuck (I figured that would be an easy way to make the bike not run on any cylinders) Compression test was pretty inconclusive because I couldn't start the bike and the battery was basically dead. The numbers I was getting are scary and I attributed it to incorrectly testing (using the kicker). The only thing I got was one backfire out of the exhaust.
I got my truck and loaded the bike up to take home. Drained the oil - The oil was low. Probably 1.5 qts low (it was full when I left). The oil has a sickening burned smell to it. I mean, it smells terrible. Maybe the ZDDP makes it smell? No metal flakes or shavings in the oil that I could see.
When I crank the bike it sounds kind of sick - not sure if the starter sounds sick or what? Kicking it over feels completely normal - no strange noises or anything like that, smooth action with the same resistance I am used to. The plugs look like they were running hot, maybe too lean or timing too advanced? Exhaust also looks bluer than it was at the start of my ride...again, these were new headers so they only have 600 miles on them...

I have not touched it since. Unfortunately between work, having a small kid, and multiple bikes I have to use time wisely...and honestly I am kind of dreading getting into this. I know the oil consumption ain't right. It does leak a bit from the stator grommet and front right cam cap, but there is no way in hell all of that leaked out on the ride. A few years ago I tried a low profile breather on the bike - I know what losing that much oil on the road is like (everything from the breather back literally dripping with oil at the first gas stop).

I suppose my next move is to pull the cam cover and see how the cams look or if maybe the chain jumped a tooth? Whatever happened is affecting the whole engine. Even if one or two cylinders had problems (fouled plug, carb problem, stuck valve, anything that would affect a single cylinder) the engine would run shittily on the remaining cylinders. Everything is pointing to some sort of timing or ignition issue - I need to check the ignition timing as well, although the dyna-S plate had not moved a millimeter and the screws were tight.

Oh yea, almost forgot - When I was scratching my head thinking about the weak spark / 9v to coils (relay mod has not been done - factory power distro to coils) I decided to measure the resistance between the 3 yellow stator wires (idea was if the bike is not producing power the battery doesn't have enough juice to make good spark and turn the engine over - kind of a long shot since it is a new battery, etc.) BUT here are the resistance readings -
Between 1 & 2 - 1.6 ohms
Between 1 & 3 - zilch
Between 2 & 3 - zilch
I verified this test with two different meters multiple times. So this leads me to believe the stator has faulted somewhere. Could this be related or unrelated to the bike straight-up dying, not starting at all problem?

Anyhow, I am curious to hear any input / advice / sympathy / criticism from ya'll. Attached are some pictures I took during happier times.

Are you 100% sure the cams are timed right?

Multiply possibilities but the first thing that jumps out to me is that 9v to the coils. Now I'm assuming you have a good fully charged battery when you did the test. If that is the case pull the primary wires from the coils and measure the resistance of the primary winding. If I'm not mistaken should be about 3 ohms plus or minus .2 ohms but verify that prior to your test. If they measure within tolerance look at the ignition switch and or kill/run switch to be failed or failing.

Secondly your stator readings indicate a bad stator and these bikes will not run right without at least 13 to 14.5 volts measured at the battery at 2500+ RPM. With a bad charging circuit and only 11 v or so while cranking it may not start and would most certainly show a weak spark if any at all. Good tip on checking the cam chain timing but your description of the problem really describes a failing coil or charging circuit.

Now why one cylinder colder than the others? I can only guess that you have a clog in that carb or float is not set to proper height. you hint about the pipes being more blue tells me you could have a fuel delivery problem. This would be the last problem I'd concentrate on until you get the charging system working properly. You may find that this problem disappears when you get proper voltage while running.

As for low oil level when was the last time you changed oil and filter? New engines/rings can burn a lot of oil quickly without really smoking that you would notice. Now 1.5 Qts? That's a bunch. It would have been smoking like a mosquito fogger or the bottom of your bike would be soaked. I'm chalking the low level to first oil fill since rebuild and all of the oil was out. Then it would have required about 1/2 qt more than normal. Plus when you checked the oil did you use the sight window and guess at the level being 1.5 qts low? I'm pretty sure 1/2 qt low would show empty on the sight glass. So unless you drained the oil into a measuring device and confirmed only 2.5 qts came out I would say you guessed wrong at 1.5 qts low. As for the smell I don't know what ZDDP is so I can't comment. Personally I would never put an oil additive, if that is what ZDDP is, into a new engine.

Thanks for the input -
Z1Driver,
I am 100% sure they were timed right when I assembled the top end. I have not yet pulled the cam cover - one of the things on my checklist
JD-,
Will measure the coil resistance. The stator is definitely giving those bad resistance numbers. Hopefully that is the culprit for the bike dying due to weak spark. I charged the battery when I got it back to the shop since It basically ran out of juice trying to start it and dicking around with it for 2 days in the Shell station parking lot.
As far as one cold cylinder goes that is not one of my problems, probably from another thread?
I do agree the bike seems to be running lean (at least in the mid range). I did monitor header temps when I was in the engine break in process - seemed pretty normal and all similar. Carbs are (were) balanced to a pretty exacting degree.
The oil was changed at 100 miles - did not change the filter. So this oil has 500 miles on it and the filter has 600. I agree, it seems like a lot to lose and like I said in the past I have actually lost a massive quantity of oil due to that damn low profile breather - and the bike was SOAKED! Not the case here. When I began the doomed ride, the oil was about 3/4 on the sight glass. Once I got the bike back to the shop I drained it and got about 2.5 qts out. So it must've gone somewhere. The 400 or so miles prior to this oil loss was negligible.
Oh yea, ZDDP is a zinc additive recommended by many including the guy who did my head work. It is for use in flat tappet / non-roller-cam engines and helps with the friction and wear in these areas. I am not an oil specialist but it makes sense.

SO my course of action is this:
Remove the countershaft sprocket/trans cover to make sure nothing is up with the wires coming from the stator
Remove the cam cover to verify cam timing is correct. Also to make sure there is no damage to the cams.
Maybe crank the engine with a timing light hooked up to check ignition timing.
Check primary and secondary resistance at the coils.
Try and figure out where I am loosing voltage to the coils. With 12.7 or so at the battery I am loosing 3 volts.

Should be able to get serious with this by the end of the week. Thanks for the input.

yeah cold cylinder is from another thread... It kinda sucks getting old.

As for the 9v problem since you modified the stock circuit with the relay that is where I'd start. Check for 12v in and 12v out of that relay. Now that measurement should be made with the coil wires hooked to the coils and unhooked from the coils. I still think your problem is likely a bad coil. Since relays often fail by not moving the contacts but I don't know how you wired it. Could be back emf from the coils caused arcing on the relay contacts and that is the source of your voltage drop. I think if you look up good practices you'll see that some put a capacitor across the switched contacts. Also make sure your relay is rated for the voltage and current demanded by the coil primaries.

Ohms law is I=E/R so the coil demand can be determined by formula. Lets say the coils are 3 ohm each (total resistance would be roughly half of that or 1.5 ohm)and both are drawing current for most of the time. (charging) The the Current demand would be 12/1.5 = 8 amps
So I would use a minimum of 10 amp relay but 15 or 20 amp would be better.
Good luck.

del

There is not a relay wired up for the coils - factory power to them.

The latest update will probably be on Friday when I can get back into this.

Did you ever do the compression test properly? If not, then you need to. Use your truck's battery if the one in the bike is toast.

OK,
After sitting for 2 months while life happened around it, I have dug back into this.
Installed a new electro-sport Stator. This has solved the super weak spark issue and was needed because the old stator did not pass the resistance check.
Unfortunately this did not solve my main issue. Got out the compression tester - 30 psi across the board. So what would make all 4 cyl lose compression like this? Cam chain jumping a tooth and throwing off valve timing? Gotta pull the cover and check the cam timing next. And the disgusting burned oil smell still worries me...

Did you check the valve clearances and retorque the head after the rebuild? As already mentioned, the cam chain could have jumped so I'd check this when you pull the valve cover to check everything out.

Regarding the oil consumption, something doesn't seem right there. The bike shouldn't burn that much. I'm sure some here will disagree but I favor a more aggressive ring break-in process. Babying the engine like you did should be avoided. When breaking in an engine with fresh rings I like to run it aggressively around town, in a city driving cycle. Nothing crazy mind you, just accelerate through the gears and medium use of the throttle. You gotta load the rings to get them to bed into the cylinder walls.

The oil issue would tend to make me think a piston issue, as you have low compression and a lot of missing oil. You could try putting some oil in the bores to see if it brings up the compression to eliminate a valve issue, if it's the valves leaking due to valve timing etc. then the compression will not rise after injecting oil into the bore. Dependent on those findings I would then remove the valve cover and check the camshaft positions relative to the crank and the chain to see if anything got out of position.

Nessism wrote: Did you check the valve clearances and retorque the head after the rebuild? As already mentioned, the cam chain could have jumped so I'd check this when you pull the valve cover to check everything out.

Regarding the oil consumption, something doesn't seem right there. The bike shouldn't burn that much. I'm sure some here will disagree but I favor a more aggressive ring break-in process. Babying the engine like you did should be avoided. When breaking in an engine with fresh rings I like to run it aggressively around town, in a city driving cycle. Nothing crazy mind you, just accelerate through the gears and medium use of the throttle. You gotta load the rings to get them to bed into the cylinder walls.

On the vintage Triumph forum you can read pages where folks don't get their rings to seal by not being aggressive enough with initial break in, they even advocate loading the engine going up hill initially to force the rings against the cylinder walls. On Kawasaki's I recall hearing of issues with the bores glazing, when they were new, due to too careful a break in, resulting in oil consumption etc. However in this case the oil consumption seems so excessive it seems it might be more than just that, although again with the Triumphs I've heard of people actually smoking really badly as a result of the rings not sealing after a rebuild, so anything's possible.