Some KZ750/4 Questions

Would an 82/83 kz750 have a crossover in the exhaust?Mine does not-looks like stock mufflers.Can mufflers become restricted?What would be the signs?Do allcarb jets wear or just needle jets?Are these these bikes slow to warmup? My bike always needs choke and seems to take a while to warmup,pretty much runs nice.Just Wind it open above 2k and hang on,up to redline through the first 3 gears.But when crusing at about 4.5 to 5k feels like it stumbles a bit.I have had it to a bit over 80 on the hiway,not a rocket through 4 and 5th gear but I don't spend much time there.All in all I am having a blast getting it sorted,just some questions that I had.

1. Nope, no cross-over in the OEM exhaust.
2. Not sure if mufflers can get restricted, but it's usually the other way around
3. Haven't heard much about jets wearing
4. KZ's are normally cold-blooded. Mine usually took about 4-5 minutes to warm up. Always needed choke to start in the morning.
5. Have to troubleshoot more on the stumbling, but if you still have the smog system on, yank it off! Really helps with the stumbling and popping.

Good Luck!

The stock exhaust systems on the KZ750-4s have a crossover muffler connector pipe.

martin_csr wrote: The stock exhaust systems on the KZ750-4s have a crossover muffler connector pipe.

+1 As usual, Martin has the correct info. If your KZ750-4 has the stock exhaust system it should have the crossover pipe. Ed

Nope,no crossover pipe,just a bracket to the engine.Looks to be stock mufflers.
The emission crap is gone,replaced with a piece of vacum hose.

You don;t say which model you have, but they all came with connecting pipes between the two sides. Here are a couple pics that might help.

The 2 into 1 collectors have no sign of crossover pipe just interlocking brackets that bolt to bottom of motor.The header mounting collars are flat not ribbed like some I've seen.Sorry no pics yet.

The N2 diagram seems to show a mounting bracket not a crossover pipe.

I have a 750 spectre, which appears to be what you have (you should put that in your signature), and it definitely has a crossover, so your headers are either aftermarket or someone did some modification to them. The stock mufflers were finished with a black chrome on the spectres, which I haven't seen too many other places, so if yours have that, they're probably stock. I also have the flat exhaust clamps, which looking at the pictures Ed posted of parts, looks to be the case for the spectres, you can see the ribs in the E2/E3 blowup, and you can see their absence in the Spectre blowup.

Mine always needs full choke to start from cold, and usually needs it for the first couple minutes, then half choke for another probably 10 minutes. I think a carb tune would probably let me drop that a little sooner, but they're definitely cold-blooded bikes, needing choke to start doesn't signal anything bad.

As far as telling if a muffler is shot, I've never actually looked at what kind of mufflers these are. But they do slide right off the back of the header. I would guess they're a straight through with some sort of packing design, so pull em off and see if you can look through them. If you can, you should be good to go.

I've read that over filling oil can cause problems.Can some one explain?

I'll take a shot at this. The pistons go up and down very rapidly, as they do the air pressure inside the crankcase varies, so the crankcase has a breather to prevent the pressure changes from causing problems (like blowing out seals, etc.) So the crankcase must be able to breath, but too much oil can interfere with the engine's ability to breath properly because it reduces the volume of air in the crankcase. Also, if the oil level is overfilled enough, the pistons and rods can churn up the oil causing foam which is not good for lubrication. There may be other reasons, but I've always been told of the ones above. Ed