Bad Engine? -- Now with video! -- Update

Well, in reading the recent posts regarding the noise, I decided to try the easiest things first. I went out and fired up the bike, held the idle at ~1500rpm and pulled spark plug boot #1.
No change.
Pulled #4
No change.
It appears that #1 and #4 are not firing at idle but kicks in above ~3000rpm.
Thanks Kawtoy!
I know I said I checked the coils but that was last year (how long ago does something have to before you can't assume nothing has changed?). What next to find the problem? I suppose swap coils and see if the problem moves from 1&4 to 2&3. I did check the voltage to the coils a few weeks ago and it was ~10.5V to both coils. I am planning on doing the coil relay mod soon.

Post edited by: cafekz750, at: 2007/06/20 16:16

Post edited by: cafekz750, at: 2007/06/20 16:17

My punishment for the long way to perhaps a simple solution:


Post edited by: cafekz750, at: 2007/06/20 16:19

Post edited by: cafekz750, at: 2007/06/20 16:29

i would not worry about the noise just yet. it sounds like ignition to me. i think the noise is you primary chain wacking away cause a couple cylinders are cutting in and out so fast. check coil power and do a voltage drop there, and also check coil primary and secondary resistance, i am pretty sure you engine is fine.

Post edited by: flht1997, at: 2007/06/20 18:12

If you swap the coils and the problem does not follow the assume that your pilot jets are plugged. When reved up the mains will kick in and give you the fuel you need. To test if the carbs are the problem you can spray some starter fluid in the carb on the dead cylinder. If the rpm's jump and the cylinder fires then you will need to clean the jets. Always start easy and work your way into the hard work.

I think you just helped me out greatly!! I posted a question about the same noise. I heard your video and I have the same noise. My bike has been sitting for some years and I am trying to get it on the road. I just bought it (a barn find). I only get the noise at low RPMs. Were the plugs fowled out? Because #3 and #2 are fowled on my bike. I have been worried that it is piston slap (bad rings). My bike is a stock kz650c. My latest problem is that the bike doesn't want to start now. I am planning on getting a new condenser this weekend, now I plan on getting coils maybe. Any other info would help. My posting is called "Just got 77 KZ650 and It Runs"
Thanks

I thought I would give the final update on the bike. This past weekend, I finally got around to working on the bike. I bought and installed materials for the coil relay mod. I had 10V before and 12V after. I checked the coils again, I had the proper resistance for the low and high but I decided to replace them with coils from a parts bike that I have. I replaced all four spark plugs and checked the caps and wires. So far after ~60 miles the bike runs and idles great. It sounds and feels different in the low rpm. I think the problem is finally fixed. Before this weekend the bike wouldn't idle and would bog down until about 3000rpm and then the bike would snap forward and run great. I think the 1&4 coil was opening up when hot and not firing until revved up. Does this make sense? 10 years and finally it idles. Now for my next project...

way cool, I think I am going to do the coil mod on the 1000

I just had the same problem... Turns out it was the Timing advance unit and points. It was so bad I couldn't twist the advance unit to make the points move. Took it apart and cleaned and lubed it.
Idles great now.