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81 GS450 new noise Cam chain/tensionser or other issue?

  • Thread starter Thread starter Blue Falcon
  • Start date Start date
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Blue Falcon

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Recently did the valve clearance on my bike (second time since I bought it), everything was around the .05-.07 range after shims changed... well within spec. Double and triple checked. Enter bike week...rode about 1000 miles this week and in the course, new sounds appeared. The best I can describe it is a tin-pan rattle from the top end. I am used the the sewing machine "ticks" and exhaust "pings" ( not pre-ignition type ) that are supposed to be there from a well tuned bike, but the tin-pan sound concerned me. Happens at 4k and above rpm, sound is noticeable above that range. I am thinking its the cam chain tensioner. Compression good, fuel economy good, oil looks good, no loss of power/speed, idle good. Any other thoughts? I just don't want to open her up again for no reason, I just cleaned my garage floor and driveway......

Thanks,
 
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Are you sure it's coming from the engine? I had a worrysome noise a few years ago that I couldn't figure out and it turns out it was the heat shields on the exhaust - one was a little loose.:confused:
 
sam000lee said:
Are you sure it's coming from the engine? I had a worrysome noise a few years ago that I couldn't figure out and it turns out it was the heat shields on the exhaust - one was a little loose.:confused:
Click to expand...

they are tight
 
Make sure the camchain tensioner is working correctly- maybe you got some excessive chain slack. It's hard to check without removing valve cover.
 
Did you ever turn the crankshaft backwards - CCW - when you were working on it? I'm not sure exactly what happens when you do, having always avoided it, but it may be possible that the front chain guide popped up and isn't back in its little well. Or the CCT didn't like it.

Just speculating, but interested because I'm doing shims today myself on a 450. The cool thing is that all the shims are 2.60s; the bad news is that I now need four 2.55s and only have one.

The other thought is that something ended up in different place when you put the tank back on and it's rattling against it.
 
John Park said:
Did you ever turn the crankshaft backwards - CCW - when you were working on it? I'm not sure exactly what happens when you do, having always avoided it, but it may be possible that the front chain guide popped up and isn't back in its little well. Or the CCT didn't like it.

Just speculating, but interested because I'm doing shims today myself on a 450. The cool thing is that all the shims are 2.60s; the bad news is that I now need four 2.55s and only have one.

The other thought is that something ended up in different place when you put the tank back on and it's rattling against it.
Click to expand...

"thou shalt not turn crank backwards" ... nope never did. driving me nuts...gonna wind up opening her up this weekend.

sound appears around 4500, not at idle.
 
Ok, took off the valve cover, slight chain contact on the ends outside the black guide on the cover.... verdict, new gasket and tighten down right. No other apparent wearing in the top end. That part is done.

Intake valves at .05 exhaust at .07-.08

Took off tensioner... made sure all was "OK" put back together and installed, no issue. - bikecliff style before you say anything.

Tach cable was loose on the head, tightened.

Compression is great, both between 140-145... analog gauge.

exhaust is tight no apparent leaks

all bolts tight

pilots - L 2.5 R 2.75 - synced/tuned - found I can adjust them evenly up to about 3.5 on the right and 3.25 on left and keep them really close.


results... new sound now.... at 4k rpm I get a sound but only while loaded, if I pull in the clutch the sound goes away regardless of RPM. Sound still seems to be coming from the top end... can't explain it... still no loss of power or effect on bike performance, main "tin pan" sound gone, this is just a new one... more of a rattle type, does not sound like metal scraping. Adjusted clutch, no shifting issues, took an oil sample, seems free and clear. I am chalking this one up as a "GS sound" and I guess I am going to have to get used to it. More annoyance.... other note... the sound may have always been there... I think I may have honed in on it since I did a valve job an got everything back in spec... so now I have this noise.. sewing machine noise is much better lol.

I will say... mechanically, other than the sound, the bike is running fantastic.
 
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On my 77 GS400 the inner exhaust pipe came adrift from the outer pipe and only rattled at certain RPM. I'm having the same issue with muffler guts rattling lose in my 83 GS450.
 
smilinbrad said:
On my 77 GS400 the inner exhaust pipe came adrift from the outer pipe and only rattled at certain RPM. I'm having the same issue with muffler guts rattling lose in my 83 GS450.
Click to expand...

thanks...I will check that...did the sound come from the top end area or the exhaust?
 
On the 77 it was lose near the muffler joint. Sounded like the clutch was rattling apart
On the 83 I knew right away it was exhaust oriented from previous experience.
 
smilinbrad said:
On the 77 it was lose near the muffler joint. Sounded like the clutch was rattling apart
On the 83 I knew right away it was exhaust oriented from previous experience.
Click to expand...

everything tight.. same noise, no effect on performance. nothing rubbing still sounds like its coming from top end..... I dunno... just gonna chalk it up to "GS noise"... at least until I notice actual issues besides noise.

The ping sound I am getting is just like a really good exhaust ping... like from a high compression harley or a 2 stroke.
 
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pulled off the cam tensioner again.... seems to be stuck. Quick rebuild and its moving again.... hopefully this is the issue, it had a "sticky spot" that I took care of.... started her up and no noise... will have to wait to get her loaded and at speed.

edit: still have noise...grrrrrr. guess its just "GS noise"
 
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You mentioned earlier that the sound went away when you pulled in the clutch. Could the nut that holds the clutch on be loose? Usually that's problem only on the big motors, but maybe somebody had it apart and didn't get it done up or there's too much endplay.

Might be able to lever it about through the oil filler. ??
 
John Park said:
You mentioned earlier that the sound went away when you pulled in the clutch. Could the nut that holds the clutch on be loose? Usually that's problem only on the big motors, but maybe somebody had it apart and didn't get it done up or there's too much endplay.

Might be able to lever it about through the oil filler. ??
Click to expand...

I was wrong, the sound does not go away with the clutch...... I don't think it's a spun bearing or piston slap...the sound just is not right for it. The sound is coming from the top end not the crank area, only gets noticeable after warming up for a few minutes... won't do it at idle or cold... and can't hear it when I am sitting still and rev it up to 4500-6000..... I beginning to wonder if it is coming from the transmission area and resonating up.

No shifting issues, no power loss.... I am at a loss. Don't have my buddy around to help diagnose.. last time he said " it just makes that sound that is all " .... but he was 3 sheets to the wind... ugh..

I am also pretty sure it is not valve lash... Nothing less than .05 clearance.

timing is spot on.... I am at a loss and I am just guessing at this point. I really don't want to pull the engine and go over every inch.
 
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Blue Falcon said:
pulled off the cam tensioner again.... seems to be stuck. Quick rebuild and its moving again.... hopefully this is the issue, it had a "sticky spot" that I took care of.... started her up and no noise...
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Let's be annoying sure here regarding tensioner..... You saw and understood this link?

http://members.dslextreme.com/users/storagecliff/images/engine_odds-n-ends.html#A05

After correctly "resetting" tensioner, you reinstalled it,and backed off the slotted screw holding plunger shaft,etc etc.
 
tom203 said:
Let's be annoying sure here regarding tensioner..... You saw and understood this link?

http://members.dslextreme.com/users/storagecliff/images/engine_odds-n-ends.html#A05

After correctly "resetting" tensioner, you reinstalled it,and backed off the slotted screw holding plunger shaft,etc etc.
Click to expand...
Read the OP "BikeCliff style" on the tensioner. Anywho...I'm pulling it off again today to slide a new gasket on.

Edit: actually had that page opened on my phone while I installed it yesterday.... I was griping about the 1/4 turn and 1/2 from the two posters..someone make up their mind lol.
 
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Had to do some work to the tensioner.. my sticky spot was and actual.. "I'm not moving anymore" spot.... caught something I did not see the first time around. see pic... all those little gouges and nicks were enough to keep the shaft from rotating in and out. Thankfully my landlord is a retired Rolls-Royce mechanic and has an awesome set of tools.... I can fix it. Was able to smooth the nicks out and groove the area right... should have taken an after pic... I am not taking that damn thing off again. This got rid of the "tin can" rattle clack-a-clack-a sounds... currently I can't make the bike make the sound again.... will see later

I am searching for another tenisioner just in case.


View attachment 50292
 
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Get a another tensioner and install it - used two bolt mount units are plentiful and maybe $20. It's critical that plunger can slide out easily!
 
tom203 said:
Get a another tensioner and install it - used two bolt mount units are plentiful and maybe $20. It's critical that plunger can slide out easily!
Click to expand...

The plunger wasn't the issue, sliding out was easy..sliding back in is where the stoppage was... I could not rotate the gnurl enough to set the plunger all the way in....it was the spring loaded rotating shaft had a catch on it...I guess too much tension is better than none at all in this case..... The not rotating out explains why it only happened at around 4500rpm and when loaded... tension on the chain was greater and the shaft would not rotate back out any further.

I already ordered two off ebay.... total of less than $30 for the pair shipped.

My timing is still money at this point... no skipping... YAY!! The tensioner works like a champ now, but I am still replacing it.
 
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