Topic: Just about at my wits end with this bike (95 zx600c)

[MJL]

I had a long post, but decided to give the short version for now.  1995 Kawasaki zx600c runs badly. It doesnt want to rev at all, just idle. I have changed gas in the tank several times, cleaned carbs half a dozen times, changed to another set of carbs, adjusted valves, checked valve timing, checked ignition timing, changed ignitor box, checked compression (130 or more) ohmed ignition trigger coils, ohmed primary side of coils (my meter only goes to 1000 ohms) set pilot screws to 1two turns out and nothing helps. All four pipes get hot, so I know all cylinders are firing.  I'm going to order some new plug wires, caps, and plugs today, and in the meantime clean all my connections.  Any ideas from the old school crew?

[seanbarney41]

What carbs are on it?...Mikuni CV's?

[MJL]

Carbs are Keihin CVK.

[scottly]

What do the spark plugs look like?

[MJL]

What do the spark plugs look like?

As I recall, they were a bit sooty. Ive got new plugs and wires on the way.

[scottly]

How's the air filter?

[BenelliSEI]

Collapsed/ plugged muffler? 

[seanbarney41]

Carbs are Keihin CVK.

Check that someone has not improperly or unnecessarily installed dynojet kit...same as these  sohc4's You will want original Keihin brass parts...also stage III involved drilling bigger holes in top of slide, and if that is not done correctly you will get very poor high rpm performance

[Don R]

 I've had the plugged exhaust issue, it threw me a loop for a week. I called my brother and told him that I literally changed everything except the frame and exhaust, hmm I'll call you back. It turned out that the PO had stuffed the baffle with pink insulation and it got over the baffle inlet and was blown into the pipe. Lot's of carbon, it was a "ran when parked" bike.

[MJL]

How's the air filter?

Oiled foam type, doesnt change whether it's in or out.

[MJL]

Collapsed/ plugged muffler? 

Interesting... I hadn't considered that. It has dual exhaust with a crossover. I have another stock exhaust, I suppose I could swap it in and see what happens.

[MJL]

Carbs are Keihin CVK.

Check that someone has not improperly or unnecessarily installed dynojet kit...same as these  sohc4's You will want original Keihin brass parts...also stage III involved drilling bigger holes in top of slide, and if that is not done correctly you will get very poor high rpm performance

The carbs that were originally on the bike have adjustable needles. I'm not sure but I think the brass parts are original. I did swap in another rack, with original fixed needles and brass, to no effect. I have been thinking about trying to fit my cb750 carbs on just to see if there's a change, but the spacing is different and would be a challenge to fit.

Side note, I have a second engine on the bench that I have been thinking of setting up to run just to see if the carbs work with it or not.

[scottly]

What's the history on the bike? Did this start happening suddenly, or did you buy the bike this way?

[MRieck]

Check the cam alignment marks very carefully...one or both cams could have jumped a tooth. I have seen it with automatic tensioners and it is probably cause by the tensioner being loose right before it adjusts itself. It can look like they are in the correct position but.....

[grcamna2]

Take a look at the fuel valve/vacuum petcock and the vacuum line which feeds it;you may need to rebuild that petcock/install a fresh diaphragm.

[MJL]

Check the cam alignment marks very carefully...one or both cams could have jumped a tooth. I have seen it with automatic tensioners and it is probably cause by the tensioner being loose right before it adjusts itself. It can look like they are in the correct position but.....

Did that. Cams looked like they had jumped a tooth, so I set them back to spec. Even used the spare engine as a reference.

[MJL]

Take a look at the fuel valve/vacuum petcock and the vacuum line which feeds it;you may need to rebuild that petcock/install a fresh diaphragm.

The vacuum part doesnt work, when you turn the petcock on you get fuel. I had thought if that as well, and checked it.

[MJL]

What's the history on the bike? Did this start happening suddenly, or did you buy the bike this way?

The history... I didnt want to start with a long drawn out post, but now that you asked, here it is... I bought one of these brand new back around 95 or 96, and it got removed due to job loss. Ten years or more, maybe 15, I decided I wanted another one. This was the only one I could find locally. It was a mess. Plastics missing, gas tank half sanded and left to rust, lower engine case broken at the shift lever. That summer I spent a lot of time and money buying plastics, found a NOS gas tank in the right color, bought another engine which turned out to be junk, but I swapped the lower case and had a good  motor. But, it wouldn't start. That I believed to be the ignitor box. I cut the plug off (dumb!) And built a new ignition that uses GM HEI modules. http://gpzweb.s3-website-us-east-1.amazonaws.com/Ignition/GPZgmHEImod.html It ran, but I was concerned about the lack of ignition advance. I probably shouldn't have worried, because I think the timing is set to full advance and the ignitor box delays the spark as required. So, I parked the bike. Last year I bought a golf cart project that needed a motor, and I thought of that bike. I figure I  had too much money in it to give up, so I found a used ignitor box and rode around for a month. Unfortunately, I found a large puddle under the bike, and discovered it was gas and oil, like one of the carb floats didnt close and gas leaked into the cylinder and past the rings. So, changed the oil, the sprocket shaft seal where it was leaking from, the thermostat and the valve cover gasket. I also adjusted the valves whole I was in there. Shortly after, it began to run bad. I could get it to start and rev, and seem fine, but by the time I got to the street it wouldn't rev anymore. At one point it was running and revving, but had a low end stumble that made it difficult if not dangerous to ride, so I went to adjust the idle air screws and ended up making it worse. Now it will start with the choke, but only idle.

[MRieck]

All bets are off. I'm not going to read the whole post but I assume you did a leak test and compression test. I worked on a lot.....and I mean a lot being raced at Loudon.... of those bikes as well as F4I's etc at that point in time.

[MJL]

All bets are off. I'm not going to read the whole post but I assume you did a leak test and compression test. I worked on a lot.....and I mean a lot being raced at Loudon.... of those bikes as well as F4I's etc at that point in time.

Yes, I did a compression test, and all cylinders read 130-135.

[MJL]

All bets are off. I'm not going to read the whole post but I assume you did a leak test and compression test. I worked on a lot.....and I mean a lot being raced at Loudon.... of those bikes as well as F4I's etc at that point in time.

tldr I had to change the lower engine case, then rode it for a bit. Went into storage for 10 years or so, got it out and installed the correct ignition box. Rode for a moth and found gas in the oil, changed oil, valve cover gasket, thermostat, and adjusted the valves. After that is when it started acting up.

Also, I used automotive type resistor plug wires, and am switching to regular copper core wire as soon as it shows up.

[MJL]

New plugs and wires, no change.

[MRieck]

Last thing I'll add....carb slide diaphragms are sealing properly with no rips etc?

[MJL]

Yes, the diaphrams are in good condition, soft and flexible. 
I made a leakdown tester at work today, and three cylinders show practically no leaking at all. I can hear it getting past the rings, but the guage doesnt move noticeably. However, when I like Ed up what I thought were the timing marks, it sounded like it leaked from the exhaust valve. I thought I had the valve timing set according to the book, (Haynes manual) but something isn't right. Thankfully I have a second engine to compare it to.

[MJL]

Just came in from the garage. I did the test on the other engine, and had the same result: air leaking from the exhaust at tdc. But, I was on the "blow" stroke. When I gave it one more rotation to put it on compression, it was sealed up. Did that with the other motor, but as soon as I put the air on, it pushed the cylinder down. Tried again, same result. I had tohave the crank advanced to get it to stay up. Checked the other motor, it was right on the mark. There is a little spinning flag for the ignition hall effect sensors, but I know the locating pin is there, how could it move? It turns out that flag is two pieces pressed together, and they were loose!  My timing was way retarded, and now I need to check that my valve timing is correct (I changed it previously). It is 9:30 pm here, so I'll work on it tomorrow and give an update.