Cylinder #2 Cold ('78 kz650)

Good ideas, thanks.

My 1st order of business is going to be pulling the #2/3 coil and so I can switch the plug wires and confirm whether or not thats the issue (I dont think the tests that I did were completely conclusive). I'm going to do this when I get off of work tonight if it stops raining, as well as an oil change because of gassy oil.

My next order of business is going to be to take out the carb and give it a look over, o-rings, gunk, choke, etc..., as well as check valve clearances - but this might not happen for a few days. I'll do compression and voltage tests once I buy the necessary tools, which could be a week or so. Does this sound like a reasonable plan of attack?

Cheers

Edit: I'm going to get a new battery soon too, but I dont think my problem is battery related at all

Man the boys are throwing a lot of info at you all at once.

I would make a list and start working through it.

1) You have already confirmed that there is no air leak, so no need to worry about that as the problem.

2) If #3 works then the coils are fine. I would check the resistance of the spark plug cap on #2. 5 Kohms is the correct resistance. Use a mulitmeter and make sure you are within spec. The cap will just twist off of the spark plug cable. While it is off, trim a 1/8 inch off the #2 line or until you can see some shiny copper. Then if the cap checks out twist the cap back on. Not the problem.

3) Once you have resolved that it is indeed not an electrical issue and not a air leak, and the spark plug is good.....it is then time to take a closer look at your carbs. Do the clear line test for correct fuel level. If that is good then you may have to pull the carbs and take another go at #2 and make sure the passages are clear.

Are you sure that when you reassembeld the carbs, you put them together in the correct order. Ie. that fuel can get into all of the carbs? It has happened to many a shady tree mechanic in the past.

Make sure that if you have a vaccume petcock, that you have the vaccume line connected to the correct port. And not a vent. The bike will run on choke even if it is connected incorrectly.

4) Last but not least, if you have done all of the above ...resolve to check you valve clearances. It is a major PITA and you will most likely need to spend coin on a new gasket.

Get a new battery, your bike will thank you for it.

Good luck bro.

YUKABODOS wrote:

Man the boys are throwing a lot of info at you all at once.

I would make a list and start working through it.

...

3) Once you have resolved that it is indeed not an electrical issue and not a air leak, and the spark plug is good.....it is then time to take a closer look at your carbs. Do the clear line test for correct fuel level. If that is good then you may have to pull the carbs and take another go at #2 and make sure the passages are clear.

Are you sure that when you reassembeld the carbs, you put them together in the correct order. Ie. that fuel can get into all of the carbs? It has happened to many a shady tree mechanic in the past.

Make sure that if you have a vaccume petcock, that you have the vaccume line connected to the correct port. And not a vent. The bike will run on choke even if it is connected incorrectly.

4) Last but not least, if you have done all of the above ...resolve to check you valve clearances. It is a major PITA and you will most likely need to spend coin on a new gasket.

Get a new battery, your bike will thank you for it.

Good luck bro.

Thanks - and yeah... I've been getting a lot of info and things to test (some of which have gone right over my head).

I cannot verify the carbs were properly rebuilt - the PO took it to a mechanic and had them rebuilt and synched (I have the reciept, so I know they were at least supposed to be properly rebuilt about a year ago and 200mi ) I've only had the bike a week... it only has 10,000mi on it --- but it was probably sitting a lot... I was hoping I would get to put a few K miles on it before having to deal with something like this. :pinch: I've ridden it about 70mi and I'd like to think that I would have noticed only running on 3cylinders...I'm almost positive that I was running on 4 before - I really hope so anyway...

As for the petcock - all the other cylinders run golden w/ or w/o choke, the bike is ride-able like I said. I rode it 30miles the other day without #2, but the #2 header reached the same temp as the others after getting up to highway speeds for a bit. Not sure what that suggests - choke on #2 clogged maybe so it takes forever/hot/high rpms to finally warm up and run? the bike sat for 1/2hr after that ride and I started it again and the #2 was cold again long after the others had warmed...

Another question - whats the clear line test exactly? I know it involves a clear tube and float level...? I've done some searches but still dont understand...I'll figure it out.

I'm also saving anything that involves buying too much (gasket kit!) until I've ruled out all other possibilities - I'm a pretty crummy mechanic without much experience so I'm going to work my way up from the easy/simple/cheap things (Occam's razor right ) I appreciate the advice guys, I'd be lost without it

Also, I just ordered an old beat up overpriced Kawasaki repair manual off ebay - hopefully its better than the clymers!

And I'll try to get some pics up of the ugly old PITA soon

Pulled the tank, and #2/3 ignition, switched plug wires around, and the problem did not follow... more problems and pics to come

The #2 pilot might be clogged, or the carburetors need to be vacuum synced again.

Try increasing the idle (at the idle knob), until #2 cylinder starts to fire. Test by TAPPING the #2 exhaust header very quickly! QUICKLY! If it starts to fire, and you put your hand on there... :ohmy:

if it does start firing, those are pretty much the only things it could be...

Or your fuel level in the bowl is real low for some reason - thats where the clear tube verification comes in. You connect the tube to the carb drain and hold it up against the carb. Then open the drain screw and check how high the fuel level is.

GL!

Sounds more and more like #2 carb or possibly valve clearance issue. Having the carbs rebuilt a year ago doesn't mean it isn't a carb issue. The problem with with the bike sitting unused for an extended period is that the fuel forms a varnish in the carbs. If this varnish is clogging any of the tiny orifices or passages the bike will run like crap (ask how I know ). Best bet is to wait until you receive the manual then carefully remove the carbs (instructions are in the manual, all 4 come of as a single unit attached to the carb rack). Then don't completely disassemble them. Just remove the fuel bowl from bottom of #2 and take a peek inside. You should be able to clean it sufficiently without removing it from the rack or totally disassembling it. If you find that it has a bunch of varnish (it may look red) in it you should clean them all while you have them off. It may be just a little speck of dirt in the wrong place. After cleaning, I would install a fuel filter to prevent other junk that may be in the tank from getting into the fresh carb(s). Ed

Yep Yep Yep, I'm glad I can at least cross something off my list. Hopefully old carb #2 is the culprit...my nemesis...


Question #1 - on the petcock, the fuel line just simply pulled out of the petcock... it seems like it is supposed to be secured in the housing somehow, it doesnt leak, but didnt take much to pull it out.

Question #2...what the hell is this? :blink: It was on the ground after I got done pulling the tank and switching the plug wires... didn't see where it came from...



bah! trying to post pics...

See following post also.

[Click on image to enhance view.]

Good Fortune!

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Still working on it - hopefully this doesnt get too ugly :laugh:

sft1662 wrote:

Question #2...what the hell is this? :blink: It was on the ground after I got done pulling the tank and switching the plug wires... didn't see where it came from...

bah! trying to post pics...

That doesn't look like any original KZ650 part that I'm aware of. If it's made or rubber, is it possible that the PO had used it as one of the 2 forward tank dampers? When you replaced the tank did you notice if they were both in their proper place on the frame? BTW, nice looking bike! Ed

650ed wrote:


That doesn't look like any original KZ650 part that I'm aware of. If it's made or rubber, is it possible that the PO had used it as one of the 2 forward tank dampers? When you replaced the tank did you notice if they were both in their proper place on the frame? BTW, nice looking bike! Ed [/quote]

Thats exactly what I was thinking it could be. I wasnt paying too close of attention to the dampers when I took the tank off - it was starting to rain so I was just working as quickly as possible

I found a reference to the clear tube carb test in the clymer manual, I'll do it as soon as I can, and if that looks okay I'll look into the carb further.... I feel like I'm getting closer to fixing this...I can smell it.

Thanks again for the help