Snapped Timing Chain

[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.


Sprocket was busted up, chunk taken out of the camshaft


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]

Originally Posted by Water Warrior

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!!



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]

Originally Posted by 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!!



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]

Originally Posted by Water Warrior

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!