FZR600 Genesis - Engine/Gear Box Rattle

[aragonian]

Hi all,

I wanted to ask your opinion on the following:

Couple of weeks ago my FZR600 Genesis (1990, 56,000km) started to make a rattle sound. I've managed to figure out the conditions when this happens.

Basically, when the RPM is between 3,000 and 5,000 I hear a rattling sound. It is independent of gear (I've tried the first 4) but the bike needs to be moving. But it makes the sound both when I have the clutch on and off just as long as the RPM are within the 3,000-5,000 range. When stationary, I don't hear the rattle whether in gear or not.

I took the bike to a shop, because I'm a newbie and don't have any tools really. They didn't know what it is but they in their helpful (not) way said "don't worry about it"...

So, any ideas? Any input is highly appreciated, especially because in 10 days I'm supposed to drive through Europe with the bike...

Thanks!

[ragedigital]

Not sure that you're going to know until you open her up. I wish I had a better answer for you.

darrin

[aragonian]

Fair enough!

I was really wanting to hear if anyone else had had a similar problem in the past.

The real question at this point for me is whether my baby's going to make it across Europe to a nice garage...

[aragonian]

The story continues... So, I got hold of Clymer service/repair manual. According to it, slapping or rattling noises at low speed or during acceleration could be due to piston slap, or excessive piston-cylinder wall clearance.

I haven't verified this by measuring the clearance but if this is the case, what kind of costs would I be looking at? Any ideas?

[aragonian]

Ah, this one...

So, today I paid close attention to where the rattling sound was coming from and when. I dismantled the fairing panel (the plastics on both sides?) in order to hear better. There was still the troubling sound, rattle at 4,000 RPM, with and without putting the bike in gear. I also started to hear the sound while the bike was stationary, unlike before.

Now, because I was hoping that the trouble was resonance (cheapest and easiest to fix), I did a thorough check on all that could possibly vibrate. I discovered that a previous owner had managed to break some of the plastic parts which are between the engine and the fairings (?), so I took them off.

Then I hit the jack pot! or so I think for the time being...

Couple of the bolts on the metal ring on top of the tank were loose. I took out the tank cover only to discover that couple of the nuts had fallen off. Luckily I found them and installed them properly. I then started to fish for more loose parts with a powerful magnet... and voila'! I also found a bolt under the wires close to the coolant cap. The only explanation I could think for it was that somebody had dropped it there when changing the rear view mirror bracket. Allegedly that has been changed in my bike and sure enough, the bolts that hold it down are identical to the one I found. So, my guess is that somebody dropped the bolt, couldn't find it anymore, and replaced it with another one.

After these "discoveries," the rattling sound is gone... at least I didn't hear it anymore now that I quickly tried the bike. I'll go for a longer drive soon, and see what happens. But I'm really hopeful that this was the reason for the strange sound.

So, what to learn from this? Count your nuts and bolts and always check for resonance before getting too worried! At least when there's a specific range of RPM when you hear a strange sound...