1983 KZ550 - Bogs down in low gears

Hello,

New rider here. I have an 83 KZ550 that I'm working back into shape.

Overall it has been running pretty good...except for this:
The engine sometimes feels really bogged down in low gears. Pulling away from a stop it will give low power and then suddenly pull hard. Doesn't happen every time, but probably 60% of accelerations from a stop.

Has a Vance and Hines 4-to-1 installed before I bought it. I recently changed oil and filter, but that didn't change performance.

It runs great on the highway, but the sudden pulls from stop signs make it a little interesting around town.

Any ideas?

Timing advancer may be getting stuck or one of the springs is stretched - check, clean, lube or replace parts, Then check timing. Refer to your Kawasaki Service Manual for specific details. The advancer works within a certain range of rpm (1400-3400 RPM for my 79/650). Seems that's where you are having a problem.

• Does you bike idle and rev past 4000 in neutral?
• When in gear does the problem go away when you press the clutch level in all the way?
• Only in low gears 1-2, 1-3 or 2-4, where specifically?
• What oil are you using?
• Have you tested coils and spark wires, caps?
• Voltage to coils?
• Battery voltage at 4000 RPM?
• Any other visible problems flickering lights, back firing, crazy idle, smoking, gas smell?

Hi josmking,

Most likely the previous owner did not properly reconfigure the jetting when they bolted on the aftermarket exhaust system. Either that or the idle circuits in your carbs are plugged up. You say that it bogs in low gears. Would I be wrong if I suggested that the problem is really poor performance at low throttle settings? In other words, once you get to half throttle or so the bike pulls hard in every gear.

Bill

Pulling away from a stop it will give low power and then suddenly pull hard. Doesn't happen every time, but probably 60% of accelerations from a stop.

The intermittent nature of this suggests maybe poor coil connctions, clean up the terminals and crimp new female trminals on. This is quite a commmon problem on these.

Does the tacho needle jump about ever?

LineArtist wrote: Timing advancer may be getting stuck or one of the springs is stretched - check, clean, lube or replace parts, Then check timing. Refer to your Kawasaki Service Manual for specific details. The advancer works within a certain range of rpm (1400-3400 RPM for my 79/650). Seems that's where you are having a problem.

• Does you bike idle and rev past 4000 in neutral?

It can but doesnt on its own, revs up to 4k with choke all the way out

When in gear does the problem go away when you press the clutch level in all the way?

No

Only in low gears 1-2, 1-3 or 2-4, where specifically?

Actually happens in all gears, low speed/throttle

What oil are you using?

Rotella T, but problem is the same when there was Bel Ray 10w40 mineral oil in it.

Have you tested coils and spark wires, caps?

Not yet

Voltage to coils?

Battery voltage at 4000 RPM?

Haven't checked myself but stator, resistor, battery recently replaced by a good shop.

Any other visible problems flickering lights, back firing, crazy idle, smoking, gas smell?

No not at all

KZQ wrote: Hi josmking,

Most likely the previous owner did not properly reconfigure the jetting when they bolted on the aftermarket exhaust system. Either that or the idle circuits in your carbs are plugged up. You say that it bogs in low gears. Would I be wrong if I suggested that the problem is really poor performance at low throttle settings? In other words, once you get to half throttle or so the bike pulls hard in every gear.

Bill

This definitely sounds like the issue. Bogs down in higher gears as well, maybe even worse. Just easier to avoid those.

? Does the tacho needle jump about ever?

There is a reason to ask this, trying to narrow it down between fueling and ignition. The 60% intermittent bit makes me think ignition.

Carbs chronically out of tune run bad all the time at the same throttle settings. I've had about 10 of these 550's over the last quarter of a century...

Tyrell Corp wrote: ? Does the tacho needle jump about ever?

There is a reason to ask this, trying to narrow it down between fueling and ignition. The 60% intermittent bit makes me think ignition.

Carbs chronically out of tune run bad all the time at the same throttle settings. I've had about 10 of these 550's over the last quarter of a century...

Ya tach is always jumping around. I never thought much of it cuz it's one of the super cheap aftermarket ones.

Happy to answer all the questions I can. Thanks for sharing! Tons of help.

ok, electronic tacho is triggered from the coil -ve...bouncy tacho usually means coil power supply interuptions on the -ve side...maybe look at your coil connections and ignition block connectors.
Coils are'on' all the time, the ignitor unit grounds them on the -ve...

Stick with it, these 550 bikes are generally very reliable and a hoot to ride, nice to be able to thrash something to the red through a couple of gears without running out of road as on the 1100's.

josmking wrote:

Does you bike idle and rev past 4000 in neutral?

It can but doesnt on its own, revs up to 4k with choke all the way out

Right here I would question the carburetor, choke circuit, air/fuel delivery - and potentially a clogged main jet/passage. Jet size can be a factor but since the bike was running good on the 4-1 exhaust before the problem, assume the jet size is correct. Also an air leak in and out of the carb is suspect.

Aside: check compression, test coils and wires, check battery voltage running.

LineArtist wrote: ... Jet size can be a factor but since the bike was running good on the 4-1 exhaust before the problem, assume the jet size is correct.

The bike has never run properly.
From his first post:
"Overall it has been running pretty good...except for this: The engine sometimes feels really bogged down in low gears. Pulling away from a stop it will give low power and then suddenly pull hard. Doesn't happen every time, but probably 60% of accelerations from a stop. Has a Vance and Hines 4-to-1 installed before I bought it."
The symptoms are just too classic. I'd bet the bike doesn't have an airbox. What say you josmking,
Does the bike have the air box intact?
Bill

My take is if it's a jetting problem is would persist and not be intermittent. "Overall it has been running pretty good", expect for this small problem.