78 KZ1000 sooty plugs, popping exhaust

Patton, I'm going to check what the spark looks like tomorrow. I took the pods off thinking I oiled them too much, no difference. I'll also check the negative battery terminal. I'm also going to check the harness for the dyna ignition, and check connections etc. As for the pilots, they were replaced 4 years ago when the exhaust was put on. They look absolutely new and weren't overtightened. I was thinking of jetting it down some (pilots) but the plugs are that black that I don't think going down even two sizes will give them good color. Also doesn't the pilot screw control the pilot circuit at idle? If so going down in pilot size really shouldn't help at idle to 2500 rpm, am I correct with this? Thanks for the replies

Don't need to call me in Patton... you have been pointing this guy in the correct direction. From what I have been reading, I would look at the charging system FIRST as this seems to be the most likely cause of the popping and sooty plugs. If the bike were mine, I would check the battery for plate sulfation first. Using a small and inexpensive hydrometer, I would check each cell and verify none of the cells are marginal or dead. If the cells are OK, I would put the battery on a slow charge trickle charger and then measure the regulator output at the battery at idle and at 4K rpm. If I found that I wasn't getting enough power... that is lower than 14.2 VDC at 4K rpm, I would check AC voltage on the BLUE plug in each of the possible ways given there are three pins carrying voltage from the stator. If the AC voltage is low, I would then do resistance tests on the stator and try and pin the problem to either the stator or magnet.

Once the electrical stuff is checked out, I would keep in mind that sooty plugs and popping are poor combustion. Low coil power and lack of valve clearance are the two major culprits but in this case, it looks like those things have been checked so I would look at other potential issues. Possible timing issues? The jetting sounded about right for pops/pipes... the mains are a shade large but won't soot up plugs... I typically will use #20 pilot jets and #3 clip position on jet needles (those with slots for reclipping). That leaves adjustment of the pilot mixture. While it is best to do this with an EGA, you can lean the mixture by adjusting the pilot screws back to where the bike will still pull away from a stop cleanly but will not be so rich they soot up plugs. The 78 carbs are a bit hard to tune as they started life so lean that you have to really jet them up for optimum performance and they require a bit of tweeking. Set the idle mixture on each carb for max RPM using the mixture screws. Turn down the idle between each adjustment. Start at 1.5 turns out and turn the screws back and forth with the bike idling. Once you get the idle mixture tuned, then resync. Make sure your air filters are not over-oiled.

NewKZguy wrote:

...needle in the top position with a little washer underneath it....

Believe jet needle has 5 groves allowing various clip positions to regulate amount of mixture from needle jet at different throttle slide positions. Based on taper of jet needle in relation to position of throttle slide.

Also believe clip on jet needle should normally be in the middle position.

Could you clarify what is meant by in the top position with a little washer underneath it? Does this mean the clip's in the uppermost grove (leanest setting position) or that the clip's in the lowest grove thereby placing the jet needle in the highest position (richest setting position)?

In other words, has the jet needle been clipped in the leanest possible position in an effort to resolve the sooty plug condition? Or perchance set in the richest possible position?

Am thinking the clips should be in middle position and that moving then up or down is not the answer in this particular situation (but is perhaps complicating matters).

The concern with overtightening wasn't about pilot jets. It concerned possible damage to pointed tips of the pilot adjustment screws.

Am uncertain as to relevancy of the jet needle clip positions in this particular case, but do believe being in the wrong position would not be helping matters.

NewKZguy wrote:

...recently picked up a 78 kz1000A...sitting for 4 years...after new gas, plugs and a battery the bike fired right up...bike is stock except for a vance and hines 4 into 1 with a baffle, K&N pod filters, and a dyna ignition with coils and accel wires...green coils....

Is it a NEW battery?

What were conditions of storage over 4 years? Was bike garaged, carport, covered, exposed to weather, etc.??

Accel plug wires -- style (resistor or solid wire core)?
Age? Condition (cracked or deteriorated)? Checked for insulation leaks (spray mist water over wires with engine running in pitch black garage -- a short test using fan and ventilation)?

Plug wire CAPs -- Style (straight connection or resistor)? Condition? Would check connection of caps to plug wires and use dielectric grease. Same for connections of plug wires to coils.

Resistor plug wire caps plus resistor plug wires plus age and deterioration can add up to "too much resistance" between coil output and resulting spark inside combustion chamber. I use solid wire core plug wires and non-resistor caps (at least I think the built-in caps supplied with Dyna plug wires are non-resistor style). Have had experience with aged stock plug wire caps (believed resistor style) going bad.

Has an ohm check been done between #1 and #4 plug caps and between #2 and #3 plug caps? What are the readings (should be high, but don't recall specs)? Are they about the same?

Dyna wires are inexpensive and include the caps already built in. Would be a sure easy way to eliminate any existing problems between the coils and business ends of the plugs.

Dyna plug wires - Z1E

Post edited by: Patton, at: 2007/06/13 14:17

Post edited by: Patton, at: 2007/06/13 14:22

the needle clip is in the very top slot, making it the leanest setting, and it has a very thin washer under it. The wires are accel, not sure how to tell which ones they are. They look good, and I doubt all 4 would go at the same time. I sprayed them with water and they aren't arching. Plugs are non-resistor b8es. I tried turning the pilot screws all the way in, leanest setting and the bike seemed to run worse. I checked timing and it's correct and the advance works. Maybe it's just a charging issue. But even a normal charging bike only puts out like 12.6V at idle, and this is where I have my problem, idle to 2500, and my bike puts out 12.6V at idle, it just doesn't go up much from there, which is why I'm also working on the charging issue, but right now the way it's running is more important to me. As for the battery, it's brand new. I also tried a different battery from my brothers bike, just to make sure. It still charges and runs the same. His bike runs perfect and charges normal, so that leads out the battery. I checked the stator output and it was between 60 and 70V AC if I remember correctly, which lead me to either the rectifier or the regulator. But I'm not sure how to test them. Thanks for all the advice, I'm soon about to give up.

Spec for secondary coil winding measured between plug wire tips without caps is 10.4 - 15.6K ohms. Test both coils. Repeat tests with plug wire caps in place. What are the readings?

What about the good fat spark at idle with plugs removed from engine? Existing plugs may be fouled beyond recovery. Do new plugs improve this spark?

If plug wires long enough, may clip short amount from plug ends to give fresh core for cap screw insertion. Use dielectric grease here and where wires insert into coils.

Would also double check integrity of metal clamp fitting at coil end of plug wires.

Believe resistor (supressor) type plug wire has a graphite core (or something other than copper wire) and that copper wire is best for your bike.

Am still leary about condition of the plug caps.

Would it be feasible to borrow your brother's carbs for a test run on your bike?

Back to basics--

Given proper voltage to coils, correct ignition timing, good compression, adequate clean fuel supply, proper float levels, good coils and plug wires, and perfectly clean carbs, there is precious little remaining to explain poor combustion other than adequacy of spark.

Where proper voltage is reaching good coils but fails to produce a good spark at the business end of the plugs -- here are some reasons: poor connection between coil and plug wire; faulty plug wire; poor connection between plug wire and plug cap; poor connection between plug cap and plug; bad plug cap; bad plug. So what about the good fat spark at cranking rpm? When all is said and done with regard to the ignition, it boils down to the quality of a properly timed spark at the business end of the plug.

Patton, thanks for the response. I checked the spark forgot to mention it. It looks real good, bright and fat. The plugs obviously were fouled, I've put who knows how many sets of plugs in this thing for testing, so plugs haven't been an issue with the running concern. I'll check on the plug wires and coils. I can tell you that the plug wires look like the same style that would be on a car. Which means I can't cut them short to put new ends on. I have very little time to work on the bike the next couple of days so if you don't see a response that's because I haven't worked on it. The next thing I'm going to do is check coil resistance, and plug wire resistance, probably change plug wires all together, and I'm going to pull the valve cover and check valve clearance. I'll let you guys know what happens but it will probably be early next week.
Thanks again for all the input

I think everything you are doing is good except the only that makes much sense, in terms of making this bike right and getting good combustion is to trouble shoot the charging system issue. You SHOULD get about 12.6 VDC at idle but at 4K rpm, you should get 14.5 VDC. What voltage do you get at 4K rpm? Fix the charging system and you may fix the combustion issue.

Accel yellow wires are 8.8mm and often don't fit well in the coils. The wire itself is just wire but the insulation is much thicker than normal which is about 7mm OD diameter. If you have Accel wires stuffed into holes in coils, make sure that enough insulation has been whittled away so that the wires are firmly planted on the contacts inside the coils. I generally use Dyna wires which are 7mm and fit well without whittling insulation because of the inherent contact problems from the yellow wires.

George, at idle the w/ the headlight off the bike puts out 12.6V, with the headlight on it puts out 12.3V, at 4K with the light off 13.1V. I checked AC voltage at the wires coming out of the case from the alt. 60-70V AC, so I'm leaning either towards rectifier or regulator, there separate and one is on either side of the bike. All wiring is intact, all connections good.
thanks

well I had a little time tonight and checked the valve clearance. It was good, all had .05-.06mm clearance. So I'm not going to mess with that part of it. I checked the plug wires again. They are yellow and say 7mm copper core. I thought they were accel but they don't say accel on them. They do look kinda old, and I hate that they are yellow, so I'll probably just replace them. I did check their resistance, each wire had .2 to .4 ohms, not K ohms, just plain ohms. Doesn't that seem really low? But isn't the lower the resistance the better?

If you get a consistent 13.1 VDC at 4K rpm with good AC coming from the stator, I would recheck connections; especially the feedback connector which is generally brown. Clean connections with contact cleaner and lube them with dielectic grease. Trace your battery negative lead down to the engine or frame and ensure it is connected solidly and re-check the black/yellow wire coming off the regulator (or reg/rec) and make sure it connects solidly to a ground and follow that ground to ensure that it is solid. When you have a consistently somewhat low reading, it is generally connections.

As far as the wire resistance, how was this check made? I haven't seen yellow non-Accel wires. I use Dyna wires as they have the caps pre-installed and are reasonably priced. They come in black, red and blue, I think. Copper core wires will work fine. If you pulled the wires out of the coils and measured resistance end to end, it should be pretty low.

If you are looking to check the primary and secondary coil windings for shorts, the easiest way is to check resistance... the primary windings can be checked by putting your meter leads in VDC scale on the two small lugs where ignition and power are connected. Do this with the ignition switch OFF as it is easy to touch a probe on one of the lugs and touch the frame which causes arcing and blown fuses. Anyway, you should have nominally 3 Ohms resistance... if the resistance is considerably higher, the coil is just old and worn and you will get a weak spark. If you find it measures infinite, the windings are shorted. You can also measure the resistance of the secondary windings by pulling out the plug wires and touching the contacts where they would seat... put your meter in Ohms but a higher scale.... x20K or so. You should have somewhere between 12K and 18K Ohms in most cases. It is also important that both coils read more or less the same.

I checked compression again. The first time I checked compression, right after I got the bike, I checked it by kicking it over with the kickstart, since the battery was dead. This time I checked it by using the electric start. I removed all the plugs and held the throttle open. Each cylinder put out 80-90 psi. I then checked it by kicking it over with the kickstart, and each cylinder put out between 120-130 psi. I poured a real small amount of oil in each cylinder at a time and checked it using the electric start, and each cylinder went up 15-25 psi. Anyway, I didn't know if there is a right and a wrong way to check compression on a kz or not. Have any of you guys done this before and had similar results? I should also add that the battery is fully charged, I removed it from the bike and put it on a low amp trickle charge overnight, so it's deffinetely turning it over like it should be. And on top of the sooty plugs, the bike is pretty hard to start, which is leading me even more towards worn rings/bores.