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GS450TZ has a VERY LOUD rattle / can you watch the video?

  • Thread starter Thread starter pricebill
  • Start date Start date
does`nt sound nice bit lik extreme tappit noise but its different

sure someone on here will have a answer for u :)
ive only got a cheap earphone so cant say one way or the other
and not realy ever had motorbike engine problems

and ive only ever broke one car engine
 
could be loose shims or leaky exhaust gaskets, have you checked your valve shim clearances, and or replaced your exhaust gaskets? put your hand around the exhaust see if you can feel exhaust gas pulses being expelled around the pipe
 
Pop the top off and have a look....

Pop the top off and have a look....

First use a hose or a stick in your ear to locate the source of the sound, I bet it's in the head. Perhaps a valve way way too loose, like a shim missing, or something else in there. I wouldn't guess cam chain but maybe one of the pieces that rides on the chain is broken? Could be something to do with the cam itself. Reaching here. You will never know until you get into it. It does not sound like a bad rod or anything in the bottom end. Easy enough to find out, but let us know for sure!
 
MARVEL MYSTERY OIL!

May sound dumb, but the guy who owns the shop I get my bike inspected at listened to it the first time I took it to him (its a 450 also) and suggested putting a capfull in the gas tank to lube the top end...it worked like a charm. It sounded close to yours too. I'd try that before you go onto anything more serious.
 
Where is the sound coming from? Hard to tell from the audio. Pinpoint the source. I would guess the same as above... something bad or broken in the valve train, exhaust leak, coil or spark plug wire shorting out somewhere. Is it coming from the clutch area?

Did the previous owner give you any clues?
 
Cam chain tensioner. It's a bear to get at below the carbs but you should take it off and make sure it's functioning properly. While your at it, take off the valve cover and have a look see at the cams and tappets.
 
cam tensioner all good

cam tensioner all good

Thanks for all your advice. Today I had a spare 30 minutes and pulled the cam tensioner. It seemed plenty "springy" and in good order. I re-installed and set it at the 1/4 turn Clymers manual reccomended. Still a noisy clanging beast so it looks like the top of this thing will be coming off as that seems to be where all the racket lies. Left side top. Thank you for the idea of listening with the hose; that narrowed it down to the top left. Exhaust seems to be holding on just fine with no leaks. I guess I'll paint the gas tank while it's off...

-bill
 
Last edited:
Finally a spare moment and...

Finally a spare moment and...

I pulled the valve cover and found everything looking fairly clean and well oiled. This afternoon I bought a feeler gauge and tested clearance on all valves with the 0.04 gauge (the smallest one I had) and found no clearance. The manual says acceptable is 0.03-0.08mm. So I guess my question now is... we'll really what is my question? Is it possible that I've got four valve shims that are too large? Too large would mean valves extending too far and thus making all that racket? In my mind it's the cam that wears down over time and then you need to install larger shims to compensate for the wear. Did someone stupidly install larger shims? Previous owner knows nothing.

BTW valve clearance was checked with each cam lobe perpendicular to cylinder head (ie. lobe pointing toward the sky).

Thanks,

-bill
 
Valves wear into the seats...

Valves wear into the seats...

pricebill said:
In my mind it's the cam that wears down over time and then you need to install larger shims to compensate for the wear. Did someone stupidly install larger shims?
Click to expand...

So the clearance can decrease. Fairly common. Thinner shims will be needed.
 
The valve seats itself further in the head and causes the clearance to get smaller. If you have no valve clearance, than the valve is not shutting all the way. But I had that problem with 2 valves on my bike, didnt hear any sounds like you did.

I did hear an atv once with a loose cam chain the kinds sounded like your bike does. I ended up adjusting the tensioner which tightened the chain, sound went away.
 
Hi pricebill!
This sounded like a familiar sound to me. When the engine is reving bend down and watch the cam tensioner "knob" - is it moving?
My -81 GS450 developed this sound after a top end rebuild - it turned out that two cam bolts got overtightened and the subsequent heat expancion caused them to snap (luckily they were not on the same cam bearing).

Anyway the loose bolts caused excess vibration of the cam chain, which started to rattle like this. When I eventually found out about the bolts the cam tensioner was beat up. It had developed grooves on the plunger that made it bind up, and I think the spring was getting soft after 30 years to.

To make a long story short - I ended up with rebuilding the tensioner as well, and grinding the plunger smooth again. Didn't replace the spring though and that causes the tensioner to rattle at startup sometimes.

Hope this helps
-blo
 
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