idle nosie

Hi everyone,

New to the forum. I just picked up 79 KZ650. Nice bike, runs good for the age of it and miles (22,000). One question for the experts out there. I have a rattling noise that is coming from the tranny during idle, or at least it sounds like its coming from there. It doesn't seem to cause any bike issues. It accelerates normally and no leaking. Granted, I still need to do a thorough tune up, but wondering if anyone had any ideas or if this is normal. Thanks in advance.

i have the same on my 750, goes away after like 2000RPM, never did find out why it does it?

kainh wrote:

Hi everyone,

New to the forum. I just picked up 79 KZ650. Nice bike, runs good for the age of it and miles (22,000). One question for the experts out there. I have a rattling noise that is coming from the tranny during idle, or at least it sounds like its coming from there. It doesn't seem to cause any bike issues. It accelerates normally and no leaking. Granted, I still need to do a thorough tune up, but wondering if anyone had any ideas or if this is normal. Thanks in advance.

I'm hearing something that sounds like you describe on my KZ750 I just bought... To me it sounds like its coming from the engine though, goes away when you gun it, and only very noticeable at idle... Doesnt have me overly worried (yet), I'm used to hot rod car engines with similar noises, usually from the timing chain, on those its normal and expected, I havent been around enough KZ's to know if its 'normal' on these though :whistle:

Sounds like your cam chain needs adjustment. Do you have a manual?

a friend is sending me one this weekend. I will verify the cam chain. thanks for the replies

Also if the carbs are not perfectly synced the primary chain will rattle. That's where the KZ1000 gear grive is a welcome design feature.

The 650's have a chain driven bottom end that makes noise at low rpm. A carb sync may quiet it down.Mine never went totally silent.

RomSpaceKnight wrote:

The 650's have a chain driven bottom end that makes noise at low rpm. A carb sync may quiet it down.Mine never went totally silent.

Do you know if this is the same w/a 750 twin? I've been able to get mine running (off and on) and I hear a rattling noise also. Adjusted the cam chain tentioner and it actually seems as if the noise is louder:(
I'm still having trouble keeping it running so I haven't done a carb sync, yet.

ronjones wrote:

RomSpaceKnight wrote:

The 650's have a chain driven bottom end that makes noise at low rpm. A carb sync may quiet it down.Mine never went totally silent.

Do you know if this is the same w/a 750 twin? I've been able to get mine running (off and on) and I hear a rattling noise also. Adjusted the cam chain tentioner and it actually seems as if the noise is louder:(
I'm still having trouble keeping it running so I haven't done a carb sync, yet.

Yes, your's uses a chain, plus there is a chain drive balancer driven off the crankshaft too. Could be one of these rattling. (No balancer on a KZ650, only on a 750 twin).

I vote for a cam chain adjustment.

thanks to everyone for their input. I will try the cam chain adjustment first and let everyone know. I was also planning on rebuilding the carbs, so hopefully those two things help out.

RonKZ650 wrote:

ronjones wrote:

RomSpaceKnight wrote:

The 650's have a chain driven bottom end that makes noise at low rpm. A carb sync may quiet it down.Mine never went totally silent.

Do you know if this is the same w/a 750 twin? I've been able to get mine running (off and on) and I hear a rattling noise also. Adjusted the cam chain tentioner and it actually seems as if the noise is louder:(
I'm still having trouble keeping it running so I haven't done a carb sync, yet.

Yes, your's uses a chain, plus there is a chain drive balancer driven off the crankshaft too. Could be one of these rattling. (No balancer on a KZ650, only on a 750 twin).

Thanks Ron and good luck, kainh.