Had exactly the same problem which was doing my head in. I ended up stripping the engine completely to no conclusion..BUT it is now cured.. Very simple after all that.. Changed oil, filter to high grade 10/40 and made a oil filler breather. The only reason I came to this check was from time to time I noticed the bike had more torque than before and the clutch would become stiff and heavy. So after no end of research and came to my own conclusions I ended up thinking there may possibly be too much air building up in the crankcase and causing loads of torque to release the air pressure because after a short blast the torque would slacken off and would get a rattle..


Now just to point out my fazer 600 98 model has a few performance upgrades which may not of helped with mine but after I've made a oil breather to replace the filler cap, blocked off the air inlet to the air box and rerouted the crankcase breather pipe, all rattling has gone and even the fuel economy is better, and throttle response is 100% better. Hope that gives you some more insight into a cure for you..

interesting! would be worth doing a little how to on this or at the least a few pics please

well after a long time I finally had the chance to get round to having a go at getting the bike back on the road.


Unfortunately that wont be happening for while! however on the plus side (not really a plus) I have discovered the source of my rattle.

Some how i have chewed through my big end shells and scored the crank 

i payed £4.90 including cutting and postage but you need the code!


http://www.keytrader.co.uk/Vehicle-Keys/Motorbike-Keys/YAMAHA/YH35RBP-Key-Blank.html

A few questions
What mileage is on the engine?
Is the tensioner working correctly?  They rarely fail but can stick from lack of use (Rust). Does it move in and out freely with the ratchet off the splines. Are all the pieces including the ball bearing back in the correct order?
Were all the valve clearances set correctly and the cam shaft caps put back in the correct positions
Does the chain have the right number of links? 130 incuding the soft link, it would not be the first time I have seen somebody fit the wrong length chain.
I think you will have to recheck everthing metodically even down to counting the number of links.
The only thing I came accross many years ago on a  honda which caused the chain to rattle after installing a brand new one was a damper which had gone soft., but I have never heard of it happening on a fazer.

i've just gone over 20000 miles its an 03 fzs600
the tensioner is not sticking, looks clean as a whistle, yep bearings springs back in, even tried the extra bearing trick but no luck.
valve clearances were checked and all within tollerance


now chain links did pop into my head as I didnt do the chain myself, next time i get chance to take the cover off i'll see if i have more than 130 links


im going to replace the springs in the tensioner with a rod the correct length, making it a manual tensioner effectively and removing the slight play. just to rule out the tensioner as a problem.

I would not think so, it may fit in the hole but it looks to short
What exactly do you mean by "I have worn the backing off my intake chain damper and this may be a solution."?
Ther are plenty of FZS600 ones on ebay at reasonable prices

i mean this, think this combined with a worn tensioner could be the source of my rattle.





photo taken down the tensioner hole, looks like the damping material on the intake side cam chain damper has worn away.
my intention is to modify or build a manual tensioner with some damping material on the end. failing that i'll have to split the case and replace it 

well after my mechanic mate talking me into changing the cam chain (for the price of a new chain its not worth risking etc) its not the chain lol

so now me are back to the tensioner, after having it out the 5th time we noticed some play when the spring is in.


when you try to push the tensioner back out the ratchet is locking fine under pressure but there seems so be a good 5 mm movement between clicks.
so what im trying to explain is under compresion the tensioner locks but when released the spring will push it back out about 5 mm without moving on to the next click. think that makes sense. so is it possible that the tensioner is bouncing on the spring?


took a picture today of the contact surface between the tensioner and the guide, down the tensioner hole. i have nothing to compare but it looks like there could be some indication of wear.




any ideas?

Poll results are not exactly helping matters are they? 

nope not really 

I'm with darrsi on this one. If (i think you are) you are the same poster that recently drained what looked like engine oil out of your cooling system, have you flushed the system out yet and replenished it with the correct amount of coolant ? I would suggest this is the way forward 1st. Maybe even try a borrowed or 2nd hand water pump to try at the same time as i imagine it wont have done yours much good having that gunk circulating around in it ? I know you have stated that you have inspected the water pump and all looks to be ok but as others have said, it could well be the source of your mystery noise.

yep i drained it again yesterday, it still had a slight smell to it and was slightly discoloured. as you say with that amount of gunk i would imagine the radiator will be holding a fair amount of it and its leaching back into the coolant. so perhaps i will have the radiator off and give that a flush with white spirit also. it now has rad flush in which i will run a few times and then drain that off again. give it a good flush and top up with coolant. then monitor the situation.

with the amount of dark coolant drained first time, i would imagine my oil level would have dropped significantly. which it hasn't, touch wood, yet

Just out of interest as i'm chasing a rattle and I've done less than 20,000.

how many decibels is the standard horn? i have an old horn off a scrap clio,  i was planning on adding this as well as the standard horn.

Timing would want to be off by a good few teeth before it would bring compression down to 90psi and the  valves would be hitting pistons by then.
When I replaced my chain, the old one was one 1 1/2 length longer than the replacement.
I check the valve clearance for a friend last year and discoverd whoever replace the chain on his bike before he bought it had the timing on the exhaust cam out by one tooh and the bike appeared to be running fine.  I  lifted the cams and reset the timing to the correct position and put it all back together he took it for a spin and said he found absolutel no difference in the performance.
All the issues you have described point to the water pump, but you appear to have ruled that out. Never heard of cam chain or tensioner on a fazer rattling when hot and quite when cold, it has always been the oppisite. For out of balance to cause that kind of sound it would not even run.
Other possibilites are worn clutch drum, starter clutch as some else has mentioned cam shaft end float or a cracked shim or valve lifter, list is endless.
It is really now a process of elimination.

i will check the compression again when my 10mm adapter arrives, it was a quick check and if i'd done it at home i'd have taken my time with it.
might be checking the valve clearances this weekend so can check timing too, will also check the cam lobes etc at same time.












here is said water pump, nothing obvious to me when i had it out.
bearings ran smooth, if a little tight. seals looked in good nick.
i have now cleaned the pump as it was impossible to tell if anything was leaking from the drain hole due to it being caked in chain lube and muck.


i drained the water off and again had a slight rusty orange tinge and slight smell to it but this could be residue from previous coolant.
fresh in again with rad flush this time, will be putting anti freeze in at the weekend sometime.


i will certainly be keeping an eye on this and checking again in the future, haven't ruled it out yet.

Coolant also increases the boiling point compared to just water.

i did not know that