"Cluncking sound"

The KZ550 I have takes a while to get warmed up, about 3 to 5 minutes. When it first starts off it starts at really low RPM's, 100-200. It's here where I hear and feel the "clunking" sounds. After it warms up and I drive off and get it going the bike sounds and runs perfectly.

I asked an experienced mechanic at a DIY shop his opinion. He told me had a similar problem and sound. He took his bike apart, meddling around, thinking it was a BIGGER problem, but he found it was only his idle speed that was low. :dry:

I'm not sure if that's my problem, but I'd like to try it and see if it solves the sound. I couldn't find what the preferred idle speed for a 1982 KZ-550 is. Anyone know?

Also, anyone ever have a similar problem and sound?

TheDude wrote: The KZ550 I have takes a while to get warmed up, about 3 to 5 minutes. When it first starts off it starts at really low RPM's, 100-200. It's here where I hear and feel the "clunking" sounds. After it warms up and I drive off and get it going the bike sounds and runs perfectly.

I asked an experienced mechanic at a DIY shop his opinion. He told me had a similar problem and sound. He took his bike apart, meddling around, thinking it was a BIGGER problem, but he found it was only his idle speed that was low. :dry:

I'm not sure if that's my problem, but I'd like to try it and see if it solves the sound. I couldn't find what the preferred idle speed for a 1982 KZ-550 is. Anyone know?

Also, anyone ever have a similar problem and sound?

It's not unusual to sound like digesting nails when rpm is well below factory recommended idle speed rpm.

Would check out the FSM (Factory Service Manual) available courtesy of KZr Member loudhvx:

General
home.comcast.net/~loudgpz/GPZweb/index.html#home

Service manuals
home.comcast.net/~loudgpz/GPZweb/Mnls/Mnls.html

Excessive cam chain noise at normal idle speed rpm is often significantly quietened by a complete tune-up and syncing the carbs .

Good Fortune!

I'm glad to hear that!
Yes, loud has already helped me out by showing that...very helpful.
I'm awaiting for my the Kawasaki Service Manual to be delivered, hopefully today.

Is it difficult adjusting the idle speed?

I can't believe your bike will idle at 100-200 rpm; that's pretty amazing. The normal idle speed for KZ550 engines is around 1000 - 1100 rpm. You really need to adjust your idle speed up to that range. At 100-200 rpm not only will the bike idle rough and make the noises you mentioned, but even worse, it may not be developing sufficient oil pressure to keep things lubed. Ed

Ed, is it normal to have those low idle speeds when I first start the bike, or is it supposed to start idling @ 700-1,000 RPM?

After warming it up with the CHOKE & PRIME for a few minutes it gets to about 500 RPM, then after riding it for a few miles it'll reach 1,000 RPM.

No, it's not really normal to ever idle that low. You may want to raise/lower the choke a bit when you first start it to see if that brings the idle speed up to normal. On my KZ650 if I don't turn the choke down some after first starting it the engine will idle very high, so I start it with the choke on full or near full and turn it down to bring the idle within the proper range. You engine and carbs are different than the KZ650, but you may find you need to follow a similar procedure when starting the engine from cold. Ed

Ok, thank you for letting me know.

I've NEED to use the CHOKE when starting my bike up or it won't start, so I can answer this.

I usually start the bike up with CHOKE ON. From there I hear it out and gradually turn the CHOKE OFF, but usually it involves me playing with the CHOKE often, opening and slowly closing it until the bike runs on its own.

From what you'e said, I'm shocked how low my idle is then. Starting up with the CHOKE fully ON my idle speed is about 200-300, if that!

I'll know more when I get my manual in the mail on the procedure, but is there more to do than adjusting the idle speed?

Btw, ed does a bike that idle's at 1,050 RPM normally start off at around ~700 RPM on a cold day and gradually get to 1,050 RPM? I thought it was just how this bike started, starting off at 200 RPM then gradually makings its way to 1,000 RPM.

TheDude wrote: ......... but is there more to do than adjusting the idle speed?

If when warmed up the bike idles at around 1000 rpm, but only idles at 200 rpm when first started, something is wrong. Adjusting the throttle stop knob (idle speed knob) is not the answer, because if you crank that up so instead of starting at 200 rpm it starts at 1000 rpm once the engine warms up it will be idling too high.

TheDude wrote: Btw, ed does a bike that idle's at 1,050 RPM normally start off at around ~700 RPM on a cold day and gradually get to 1,050 RPM? I thought it was just how this bike started, starting off at 200 RPM then gradually makings its way to 1,000 RPM.

No, a bike that idles at 1050 rpm usually starts idling that high or even higher with the choke on, and if the choke is left on after the engine warms up the idle will usually rise even higher. Ed

With idle speeds that low the primary chain will rattle like crazy. That is probably the noise your hearing. It will also rattle at idle when the carbs are not synched.

Ed, this is where my knowledge stops and I am ALL ears. Martin mentioned he raised his 650 to 1,200 RPM to compensate for being an old bike and also because the tachometer could be old and inaccurate. I figured doing the same for my bike would be the solution to my problem, but after your comment I'm not sure that would help.

Any ideas on where to start/what to do? I have access to a shop to pull things apart and inspect.


baldy110 wrote:

With idle speeds that low the primary chain will rattle like crazy. That is probably the noise your hearing. It will also rattle at idle when the carbs are not synched.

The drive chain or the chain inside the engine head?

The primary chain, that is the large Hyvo chain that transmits the power from the crank to the tranny. The firs thting I would do is synch your carbs then set the idle for around 1200 RPM. That will usually get rid of the rattling noise.

Here's another thought - you may want to ask your mechanic to temporarily hook up an electronic tachometer to your bike, start the bike cold, and see if both tachometers agree on the rpm. If your tachometer has a problem and is reading low you could be chasing a problem that becomes nearly impossible to diagnose. Ed