Cracked sprocket & engine cover, help

[Jorsher]

Hi,

I was riding along at 80mph and my chain snapped and smashed into the sprocket cover. Oil immediately started pouring out. I pulled over and turned the engine off. There was a large crack across the sprocket cover, that crack followed onto part of the engine assemble, see photo (left side of the bike)

I have a 2007 FZ6 S2. I have left my bike with a bike mechanic, but he will not be able to look at it for another four days. Does anybody have any experience with this. I have already ordered a new sprocket cover from ebay but am very worried about the crack extending onto the engine cover causing lots of oil to come out (crank shaft cover?).

Thanks

Jorsher

 

[Motogiro]

Ouch!!!

It looks like you may have a cracked or chewed up engine block. There are two halves and where the final output shaft exits the block, you can can see where the chain may have bunched and been driven through the the block. Lower, upper or both. All depending on the damage, it may be weldable. Thinking about it, it could have also caused debris to enter the crankcase.

 

[tomari]

maybe a used engine from salvage or something is the cheapest way to go...
you can find a totaled engine and take this part only

sorry my friend this damage is expensive...

 

[Motogiro]

This might help give a better picture of the damage..
Ronayers.com Fiche Desktop Motorcycle Yamaha 2006 FZS6V FZ6 CRANKCASE

 

[RJ2112]

Looks like the upper case, to me..... bad luck. Motor is most likely just a collection of parts, now.

 

[Jorsher]

Thanks for the advice so far.

If I were to completely remove and strip down engine would it not be possible to have damaged parts TIG welded together.

Another more costly option would be to buy a second hand engine (£600) and fit myself

 

[DefyInertia]

Based on my limited knowledge and the picture above that does not show a whole lot, I'm going to vote for needing a new engine.

Why did you chain snap? Was it the masterlink that let go? If so, what type of master link was it and why do you think it failed? Not trying to pester you, just very curious.

 

[RJ2112]

Thanks for the advice so far.

If I were to completely remove and strip down engine would it not be possible to have damaged parts TIG welded together.

Another more costly option would be to buy a second hand engine (£600) and fit myself

If you take the motor completely apart to weld the cases, it would be better to completely replace the broken case part.

Welding the broken part back into place is not all that likely to result in a completely square and level sealing edge.... the motor would probably seep or actively leak oil at that point.

There's also the changes in material strength that would result from the welds.

 

[Jorsher]

Based on my limited knowledge and the picture above that does not show a whole lot, I'm going to vote for needing a new engine.

Why did you chain snap? Was it the masterlink that let go? If so, what type of master link was it and why do you think it failed? Not trying to pester you, just very curious.

I believe it snapped due to poor maintenance on my behalf, not sure what exactly snapped, I was unable to recover chain as it happened on the motorway. It happened at the end of a 100 mile journey in which I was travelling at consistently HIGH speeds. The high speeds undoubtedly contributed to the severity of the damage.

From the comments I have received on this forum, looks like I am going to have to source a second hand engine from within the UK.

 

[Jorsher]

Hi guys,

Just an update.

I managed to get another mechanic to look at the bike, he took some of the casing off to examine the extent of the damage (see additional photos). A chunk of the engine block came off. The mechanic informed me that it can be welded back on, however a complete engine strip down would be required due to the critical location of the weld. This would have apparently cost £1000-1500 for complete strip down, weld and re-assembly.

It seemed more economical to purchase a whole used engine. The mechanic informed me that taking off the old engine and installing the new one, including new sprockets/chain, engine oil etc. would cost £365. All I need to do is find an engine.

So I searched and today I managed to find a real bargain from a reputable salvage breakers with 28 days warranty. An FZ6 S2 2008 (15,000miles) no damage to engine for £300 inc vat. The engine came from a bike that was rear ended and had some damage to forks.

All in all, this mishap has cost me £665. Maybe I will do the engine install myself to save some money, or maybe I wont.

 

[JAZZ-n-FZ6]

what type of chain did you have. Was it a clip masterlink or a rivet? Just courious because I have heard of clips breaking, but never a rivet.

 

[RJ2112]

Jorsher, you are on the right track.... swapping out the whole motor is the best chance of success. I'd suggest you offer to assist the mechanic in the engine transplant, or find a mate who's good with a wrench, and assist him.

There are a few points that are critical with the frame design used on the FZ6. That cast aluminum beam design can have BIG problems if it is not torqued correctly. If something is left loose, the frame will suffer for it. If it were a steel frame, I'd suggest doing it yourself. With the extra caution needed with the somewhat brittle aluminum, it's something to think about.

 

[bazza]

Thanks for the advice so far.

If I were to completely remove and strip down engine would it not be possible to have damaged parts TIG welded together.

Another more costly option would be to buy a second hand engine (£600) and fit myself

Me personally I would do up your engine even if it means spending a bit more in $$.
Reason being I had a bad experience 5 years ago, had an engine throw a bigend bearing, at the time it was less expensive to just get a secondhand motor from a reputable yard. Put engine in and it blew smoke like you would not belive, tried to send it back and they said I bought it as is NO REFUND.
So ended up doing up original engine.
Back pocket was very sore indeed.

 

[TownsendsFJR1300]

A close up picture of the damaged area, with the sprocket off and wiring out of the way, CLEANED UP, would help in determining if welding the section is possible.

If the cracked / broke section supports a bearing, I probably wouldn't weld it.

Should it be an area that's not critical, it may be able to be welded.

Looking at page 5-58 on my 07 manual shows a flat piece of aluminum block where your chain probably went thru. There are NO bearings /supports nearby, just the shaft the sprocket is on, the next closest is the crankshaft, which is quite a bit away from your probable damage.

If the chain went thru both the upper and lower case (at the seam), that would be a problem without dissasembling the cases...