Timing Chain Gremlins Attack

[twistit]

I've had my 97 Gs500 for about half a year and love it.  Got it with only 7k original miles and it is cherry.  But I noticed a kind of muffled rattle when I was coming to a stop light and rolled off the throttle.  I read that the tensioner is automatic and thought it might be a characteristic of the tensioner.  Mistake. 

Two weeks ago I'm coming down a long twisty hill on brakes and compression and I hear a faint high pitched whirring "wheeezzzh" sound coming from the motor and limped to my cousin's a mile away and eventually got it home where I have the motor out and on the workbench coming up with a game plan for the fix.

While on the bench, I removed valve cover and checked the timing chain tension.  It was very tight, almost like a banjo string.  This seemed excessively tight to me.  I pulled out the removable rubber guide and peered down in there with a light and couldn't see anything obviously out of place, broken or worn.  The rubber guide had two grooves about 1/8" deep in it.  Then I  removed the chain tensioner and noticed that it was all the way out, fully extended.  When I went to turn the motor over, there was a snap sound and the chain went all loose.  Can the flexible guide get jammed somehow and bow to full tension? 

The other rubber bits looked to be in fine shape.  I noticed when I went to turn the motor over again that the flexible guide tends to get bowed from the chain running over it, grow tight and then go snap again.  Is this normal? 

I'll split the cases tomorrow and see what the guide looks like.  I"m loathing the idea of tearing the motor totally apart to put a new chain on it.  I've ordered the APE manual tensioner.  If anyone has an answer to the following questions, please have at it:

1.  Do GS500 cam chains tend to stretch radically after 10k or so miles?  My tensioner was fully extended.

2.  If so, is there a more robust after market chain available?

3.  Has anyone on the forum successfully chased a new chain in after the old and riveted a master link?  I did this on my '74 CB550, they have a kit for it.

4.  What gasket sealer is commonly used on the mating surfaces?

5.  Are there after market gaskets available?  Suzuki parts are half again as expensive as after market parts.

Many thanks
Twist

[gsJack]

1.  Do GS500 cam chains tend to stretch radically after 10k or so miles?  My tensioner was fully extended.

Twist

I put over 80k miles on my 97 GS and replaced it with my current 02 when the 97 was totaled and now have about 98k miles on the 02 and have never had a problem with the cam chain or tensioner on either.

I had a broken exhaust valve on the 02 at about 20k miles caused by a sticking bucket and had to pull the head to repair it.  That was 8 years ago so the details are sketchy now but as I recall if you just pull the tensioner without compressing and locking it back first it will just fully extend as you pull it.

I do hear a tad of cam chain noise sometimes when I back it into the garage hot and running but it's gone next time, think it's just before the tensioner takes up another notch and don't consider it a problem.  When I pull the valve cover for a valve check sometimes that short top run of the chain is pulled very tight and sometimes it's loose depending on where the engine stopped whether an opening or closing valve is pulling on it.  I've pulled that cover and looked in there many times over the past 14 GS500 years:

http://www.gs500.net/gallery/data/500/GSvalvelogs.jpg

[HPP8140]

My cam chain makes noise sometimes. Bike now has 56k

[twistit]

What about the high pitched whirring noise it was making?  Is there anything else other than the chain that could make such a noise on an engine with such low miles? 

1.  Do GS500 cam chains tend to stretch radically after 10k or so miles?  My tensioner was fully extended.

Twist

I put over 80k miles on my 97 GS and replaced it with my current 02 when the 97 was totaled and now have about 98k miles on the 02 and have never had a problem with the cam chain or tensioner on either.

I had a broken exhaust valve on the 02 at about 20k miles caused by a sticking bucket and had to pull the head to repair it.  That was 8 years ago so the details are sketchy now but as I recall if you just pull the tensioner without compressing and locking it back first it will just fully extend as you pull it.

I do hear a tad of cam chain noise sometimes when I back it into the garage hot and running but it's gone next time, think it's just before the tensioner takes up another notch and don't consider it a problem.  When I pull the valve cover for a valve check sometimes that short top run of the chain is pulled very tight and sometimes it's loose depending on where the engine stopped whether an opening or closing valve is pulling on it.  I've pulled that cover and looked in there many times over the past 14 GS500 years:

http://www.gs500.net/gallery/data/500/GSvalvelogs.jpg

[twistit]

Is there a spec for the cam chain- size, number of links?

1.  Do GS500 cam chains tend to stretch radically after 10k or so miles?  My tensioner was fully extended.

Twist

I put over 80k miles on my 97 GS and replaced it with my current 02 when the 97 was totaled and now have about 98k miles on the 02 and have never had a problem with the cam chain or tensioner on either.

I had a broken exhaust valve on the 02 at about 20k miles caused by a sticking bucket and had to pull the head to repair it.  That was 8 years ago so the details are sketchy now but as I recall if you just pull the tensioner without compressing and locking it back first it will just fully extend as you pull it.

I do hear a tad of cam chain noise sometimes when I back it into the garage hot and running but it's gone next time, think it's just before the tensioner takes up another notch and don't consider it a problem.  When I pull the valve cover for a valve check sometimes that short top run of the chain is pulled very tight and sometimes it's loose depending on where the engine stopped whether an opening or closing valve is pulling on it.  I've pulled that cover and looked in there many times over the past 14 GS500 years:

http://www.gs500.net/gallery/data/500/GSvalvelogs.jpg

[Bluesmudge]

It seems to me that you are creating problems, not fixing them 

Other than a whirring noise was the bike malfunctioning in any way? The cam chain should be very tight - almost no play.

I have the APE manual tensioner and have not had any problems with it. I like that it can't malfunction but tension needs to be checked every 4,000 miles with the valves. Make sure to get suzuki brand gaskets. I have found after-market gaskets leak sometimes, especially the valve cover gasket.

[gsJack]

......................my 97 Gs500..................... I noticed a kind of muffled rattle when I was coming to a stop light and rolled off the throttle.................................I'm coming down a long twisty hill on brakes and compression and I hear a faint high pitched whirring "wheeezzzh" sound coming from the motor..........................

Many thanks
Twist

...................I noticed that my drive sprocket seems really loose and wiggly.  Is this normal after 10k miles?..............

It looks like you might have a worn front drive sprocket causing the muffled rattle when coming to a stop and not the cam chain .  They can make noises like you describe as the bike slows and comes to a stop, not normally heard under power or at higher speeds.  If the bike was not torn apart with the engine on the bench you could just put on a new $15-20 front sprocket and check it out.

The last thing I'd suspect on a 97 GS with only 10k miles on it would be a bad cam chain. 

[gsJack]

Could the faint high pitched whirring "wheeezzzh" sound be the front rotor on that twisty downhill run with brakes on?  No mention of what speed on that run.  After four old Hondas with solid front rotors I was a bit startled by that vented rotor sound when I first heard it years ago on my GS.

[twistit]

......................my 97 Gs500..................... I noticed a kind of muffled rattle when I was coming to a stop light and rolled off the throttle.................................I'm coming down a long twisty hill on brakes and compression and I hear a faint high pitched whirring "wheeezzzh" sound coming from the motor..........................

Many thanks
Twist

...................I noticed that my drive sprocket seems really loose and wiggly.  Is this normal after 10k miles?..............

It looks like you might have a worn front drive sprocket causing the muffled rattle when coming to a stop and not the cam chain .  They can make noises like you describe as the bike slows and comes to a stop, not normally heard under power or at higher speeds.  If the bike was not torn apart with the engine on the bench you could just put on a new $15-20 front sprocket and check it out.

The last thing I'd suspect on a 97 GS with only 10k miles on it would be a bad cam chain.

It's not the drive train.  The motor makes the whirring sound being revved in neutral at a stop.

[twistit]

No, the bike makes the sound being revved in neutral at a standstill.

Could the faint high pitched whirring "wheeezzzh" sound be the front rotor on that twisty downhill run with brakes on?  No mention of what speed on that run.  After four old Hondas with solid front rotors I was a bit startled by that vented rotor sound when I first heard it years ago on my GS.

[gsJack]

No, the bike makes the sound being revved in neutral at a standstill.

Could the faint high pitched whirring "wheeezzzh" sound be the front rotor on that twisty downhill run with brakes on?  No mention of what speed on that run.  After four old Hondas with solid front rotors I was a bit startled by that vented rotor sound when I first heard it years ago on my GS.

Well that noise is not the brakes or drive chain then if it does it sitting still.      How about the "muffled rattle when coming to a stop?"  A badly worn front sprocket can make some really weird noises when engine braking at low speeds when the worn hooked teeth start clicking off the chain rollers. 

[twistit]

This time my imagination was not playing tricks on me.  It was a high pitched whirring "weezzh" noise that wasn't there one minute and there the next and growing worse as I limped into my cousin's place.  He heard it too.  The engine should not be making this sound.

It seems to me that you are creating problems, not fixing them 

Other than a whirring noise was the bike malfunctioning in any way? The cam chain should be very tight - almost no play.

I have the APE manual tensioner and have not had any problems with it. I like that it can't malfunction but tension needs to be checked every 4,000 miles with the valves. Make sure to get suzuki brand gaskets. I have found after-market gaskets leak sometimes, especially the valve cover gasket.