Snapped Timing Chain

[gaillarry]

The timing chain on my son's 2001 snapped while out riding yesterday. Luckily he coasted to a stop.

Looking at rebuilding the engine within a few weeks, have to get parts first (gaskets/chain).

Anyone rebuild one of these engines that can offer tips/advice?

Can't find a gasket kit so I'll have to order individual gaskets/seals.

[Water Warrior 2]

Get a price on all the parts you may need. That will probably scare you half silly. Then search CL for a used complete running engine. It will probably be cheaper.

[Rookie Rider]

Or just buy him another gz :/

[PimpS]

Sorry for ignorance, what is timing chain? Is it inside he cilinder?

[gaillarry]

Sorry for ignorance, what is timing chain? Is it inside he cilinder?


Timing chain or cam chain, same thing. Runs from the crankshaft to the cylinder head. Parts prices aren't that bad, it'll be a fun project.

[Skunkhome]

Is the valve train non-interfering? Since it is a relatively low compression engine I would think so.

[jonathan180iq]

Haven't heard of one of these snapping.
Is it possible that the bike was running with low oil for long periods of time? Unless the chain tensioner got messed up I don't see why it would ever be under enough pressure to cause it to snap. Can't rule out the possibility of simply a failed link. But even then, under normal riding conditions and properly lubricated... I would think if it was going to snap it would have done so a long time ago.

Anyway, follow this link to Ronayers: - http://www.ronayers.com/Fiche/TypeID/26 ... odel/GZ250 (http://www.ronayers.com/Fiche/TypeID/26/Type/Motorcycle/MakeID/2/Make/Suzuki/YearID/42/Year/2001/ModelID/6483/Model/GZ250)

They have just about everything that I can see. Gaskets are like $5 a piece and the whole cam chain package is only $80.

[Road_Clam]

The timing chain on my son's 2001 snapped while out riding yesterday. Luckily he coasted to a stop.

Looking at rebuilding the engine within a few weeks, have to get parts first (gaskets/chain).

Anyone rebuild one of these engines that can offer tips/advice?

Can't find a gasket kit so I'll have to order individual gaskets/seals.

A bit of advice, before you go foreward with the thinking "you just need new gaskets and a chain" you better dissasemble the engine FIRST for a close inspecion. I have never heard of a cam chain "snapping" for no aparrent reason. If the chain did snap, that means that the piston also smashed into the valves, which most likely trashed the cyl head. If your not sure what to look for take the engine to a Suzuki dealer for a damage assessment. You can potentially spend and easy $600+ on repairs, and if you have another issue you could potentially repair the snapped chain, then blow the engine again after a short period of time.

[Rookie Rider]

Or just buy him another gz :/

[gaillarry]

I don't plan to order any parts until I strip down the engine and see what has happened. I've rebuilt three Harley engines so this one should be easier ( I hope) but it will be a lot lighter to lift compared to an EVO engine.

[gaillarry]

Finally found the time to work on the GZ; The timing chain did snap and damage was good, but the piston, cylinder are ok.

http://i6.photobucket.com/albums/y217/gaillarry/CamshaftBroken_zps17e86836.jpg
Sprocket was busted up, chunk taken out of the camshaft

http://i6.photobucket.com/albums/y217/gaillarry/CrackedHead_zpsa0286654.jpg
Found most of the broken parts in the chain tunnel. The cover has a nice crack but the cylinder is ok.

Going to tear the engine apart looking for more broken parts. Haven't bought any parts yet just looking to see if this engine is salvageable.

[Water Warrior 2]

The cam chain adjuster likely took a bit of a smack too. Keep us in the loop.

[gaillarry]

The cam chain adjuster likely took a bit of a smack too. Keep us in the loop.
It survived but is well worn. Found replacement parts on fleabay - a lot cheaper than the dealer. When I get the parts I'll post back my progress.

[Road_Clam]

Just remember my previous comment. All those broken bits and chunks you fished out, some of which fell down into your crankcase which could potentially destroy your transmission and crank bearings down the road. Just a friendly warning....

[Water Warrior 2]

It might be worthwhile to remove the bottom inspection plate of the casing. The oil drain plug screws in to it. If memory serves me correctly it has 3 bolts and an inside screen to catch stuff. The small amount of time and effort might be well spent.

[gaillarry]

Took the engine apart, including splitting the cases, found all the broken parts. Put new piston/rings (stock) honed the cylinder - compression 160 lbs. Cleaned and lapped the valves. New gaskets. Got new and used parts $270 - all from fleabay - cheaper than the dealer. Cam chain tensioner is ok. I suspect the engine was red lined too much !!! Looking for a valve cover as this one is leaking - crack JB welded but not holding.

The hardest part was waiting for parts to come in the mail!!

http://i6.photobucket.com/albums/y217/gaillarry/GZ250BrokenParts.jpg

Used cam with gear $75
Used oil pump with gear $35
new timing chain $ 40
new head and base gasket $35
New piston/rings $85
re-used engine cover gaskets (used "The Right Stuff" gasket sealant"- this sealant is amazing)

[Water Warrior 2]

Sounds like a successful repair. Just in time for winter...................BAH HUMBUG.

[Road_Clam]

Took the engine apart, including splitting the cases, found all the broken parts. Put new piston/rings (stock) honed the cylinder - compression 160 lbs. Cleaned and lapped the valves. New gaskets. Got new and used parts $270 - all from fleabay - cheaper than the dealer. Cam chain tensioner is ok. I suspect the engine was red lined too much !!! Looking for a valve cover as this one is leaking - crack JB welded but not holding.

The hardest part was waiting for parts to come in the mail!!

http://i6.photobucket.com/albums/y217/gaillarry/GZ250BrokenParts.jpg

Used cam with gear $75
Used oil pump with gear $35
new timing chain $ 40
new head and base gasket $35
New piston/rings $85
re-used engine cover gaskets (used "The Right Stuff" gasket sealant"- this sealant is amazing)

Been wrenching bikes for 30 years, and NEVER seen anything close to this type of failure on a street engine ! Something serious caused that cam gear to granade.... the question is "what" ?

[Water Warrior 2]

WHAT is a good question. I would think you found an example of metal fatigue in one gear out of tens of thousands worldwide made for the GZ top end. Chance of this happening again are probably next to nil in the future for you and many other riders. It is unfortunate the gear broke but you were able to fix the engine using knowledge gained over the years. Many of us, including myself, would have been at the mercy of a dealer for repairs.

[OldNTired]

WHAT is a good question. I would think you found an example of metal fatigue in one gear out of tens of thousands worldwide made for the GZ top end. Chance of this happening again are probably next to nil in the future for you and many other riders. It is unfortunate the gear broke but you were able to fix the engine using knowledge gained over the years. Many of us, including myself, would have been at the mercy of a dealer for repairs.


When I tore mine apart, I noticed that a couple of bolts (especially one of the two that hold the gear to the cam assembly) were a bit loose, and from what I could see had NO LocTite or similar product ever applied to it. All it would take is even a miniscule amount of excess vibration to loosen the bolt to the point where it would eventually wear (or bend) the lock plate; once the bolt works loose the other would loosen. Once loosened it would hit the side of the head and the pulley would be hit. That's not what happened to mine, but I could see it happen at some point way in the future, depending on miles driven and how you drive it.

If my typing seems like I'm falling asleep it's because I am. I just sat at the hospital for 1 1/2 days waiting for my grandson (the first) to come into this world. Ten lbs (screw the metrics!) one oz and about 2 feet long!

[Water Warrior 2]

WHAT is a good question. I would think you found an example of metal fatigue in one gear out of tens of thousands worldwide made for the GZ top end. Chance of this happening again are probably next to nil in the future for you and many other riders. It is unfortunate the gear broke but you were able to fix the engine using knowledge gained over the years. Many of us, including myself, would have been at the mercy of a dealer for repairs.


When I tore mine apart, I noticed that a couple of bolts (especially one of the two that hold the gear to the cam assembly) were a bit loose, and from what I could see had NO LocTite or similar product ever applied to it. All it would take is even a miniscule amount of excess vibration to loosen the bolt to the point where it would eventually wear (or bend) the lock plate; once the bolt works loose the other would loosen. Once loosened it would hit the side of the head and the pulley would be hit. That's not what happened to mine, but I could see it happen at some point way in the future, depending on miles driven and how you drive it.


If my typing seems like I'm falling asleep it's because I am. I just sat at the hospital for 1 1/2 days waiting for my grandson (the first) to come into this world. Ten lbs (screw the metrics!) one oz and about 2 feet long!
That seems highly likely as the pics show a break right at a bolt hole. Thanks for mentioning your observation and solution with the Loc Tite.

Cogratulations on your 1st grandson. Must be a great feeling.

[OldNTired]

[quote="Water Warrior":1ufc768e]WHAT is a good question. I would think you found an example of metal fatigue in one gear out of tens of thousands worldwide made for the GZ top end. Chance of this happening again are probably next to nil in the future for you and many other riders. It is unfortunate the gear broke but you were able to fix the engine using knowledge gained over the years. Many of us, including myself, would have been at the mercy of a dealer for repairs.


When I tore mine apart, I noticed that a couple of bolts (especially one of the two that hold the gear to the cam assembly) were a bit loose, and from what I could see had NO LocTite or similar product ever applied to it. All it would take is even a miniscule amount of excess vibration to loosen the bolt to the point where it would eventually wear (or bend) the lock plate; once the bolt works loose the other would loosen. Once loosened it would hit the side of the head and the pulley would be hit. That's not what happened to mine, but I could see it happen at some point way in the future, depending on miles driven and how you drive it.


If my typing seems like I'm falling asleep it's because I am. I just sat at the hospital for 1 1/2 days waiting for my grandson (the first) to come into this world. Ten lbs (screw the metrics!) one oz and about 2 feet long!
That seems highly likely as the pics show a break right at a bolt hole. Thanks for mentioning your observation and solution with the Loc Tite.

Cogratulations on your 1st grandson. Must be a great feeling.[/quote:1ufc768e]


It is, it is, thank you. The three granddaughters are great, but there is something special about the Grandson.
As far as the bolts, my mistake, I should have mentioned them at the time. I was just too happy to get it running to mention all the 'little' things I came across. One of the bolts was one of those that holds the top of the engine mount to the frame - that sucker had worked loose almost a quarter inch! No LocTite, no locking nut.

[mrlmd1]

One of the factory assembly workers must have been a little pissed on that day when he put your bike together, to try and get back at Suzuki, not you, but you bore the brunt of it.
Nice job in diagnosing and finding the problem, then getting it all back together.
Your son should be happy when he gets his bike back.