How bad is this ?

[drbaig]

I think I've found the arcing issue on the bike.

Noticed it whilst changing oil.

So how fubar is this situation ?

https://imgur.com/a/1RTCB
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yzf 600r

[RhynoCZ]

How far does the crack go? I'd use some ''liquid metal'' compound to ''glue'' the crack and ride it. The other option would be a new crank case.

I wonder, what happened there. The alternator cover sure looks alright.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[drbaig]

I crashed a few years ago and the gen cover was damaged but this crack was not there last time.

https://i.imgur.com/Y9PAtiR.jpg
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yzf 600r

[RhynoCZ]

Maybe there was a microscopic crack, that just spreaded over the time. I think, it's time for a new crank case. I'm no metallurgy expert, but I wouldn't ride that. Maybe some more experienced lads would have a better solution for you, but I find this beyond a reasonable repair.

Swapping the whole engine would be actually easier and quicker, than taking yours apart and swapping just the crank case.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[stinkwheel]

A dry alternator on that bike right? That's not an oiltight compartment the crack is above?

I would drill a small "stop hole" through the casing at the point of the crack to stop it spreading further, slap a blob of JB weld or that metal putty that looks like a liquorice allsort over it to stop water getting in and carry on riding.

If it's an oiltight compartment... Well, I'd probably do exactly the same but being more careful about the prep before applying the epoxy.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[drbaig]

Its dry. Thundercat.

Gonna use JB weld. Thanks
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yzf 600r

[Hahadumball]

fix with plumbers tape and sell to bcf member

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Fin: no matter how much I look at It I can't understand what was going through my head, all I remember is going about 80 and redlining it to stop it seizing.
360 Deg... Five 1/4 turns. :- Teflon-Mike 18 Jan 2015

[c_dug]

[Rogerborg]

[spottedtango]

[Pete.]

Drilling a hole does stop the crack propagating BUT most cracks continue past what is visible - sometimes a long way past. If you don't find the end you're wasting your time.

Dye penetrant testing will show the whole extent of the crack.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[drbaig]

I will put a drill through it if I can. It is at such an awkward angle with the ac magneto in the way.
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yzf 600r

[Pete.]

It looks like it has been there for a long time. Personally I would do nothing at all with it unless it starts leaking oil, except perhaps use a sealer to keep the moisture out.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Nash GT]

Weld a sprocket on it
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Suzuki GSF600N

[drbaig]

When I replaced the gen cover two years ago it was not there. So I was surprised to see the crack. And I thought ah so you have been most probably the cause of arcing as there is signs of rust inside and I've changed the whole lot plugs cap leads coils and it's not stopped.

I've filled it with jb weld. I'm not sure if I can get a drill to put a hole at the end of the crack. Although I will try.
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yzf 600r

[RhynoCZ]

I would be hesitant to drill there, without taking it apart first. I'm a bit paranoid, when it comes to drilling into the crankcase/gearbox, though.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[Pete.]

[drbaig]

Hole, gloop. Packed from both sides. Job done.

https://imgur.com/a/ExDja

BCF to the rescue as always.

Thanks guy.
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yzf 600r

[RhynoCZ]

I'd drain the oil, just in case. Don't start it yet.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[Pete.]

[drbaig]

It goes through and through. I could see through the hole. I packed it from the back side as well.

There is nothing for the swarf to go but fall out on the floor or out the back on top of the engine out of the back.

It is a dry alternator and the part where the crack is/was goes upward. There is nothing at the back. Well fuel and carb lines etc but the whole was not into the engine block. The top part sticks out separate if you get what I mean.

If you look at the engine. There is nothing behind the top of the gen cover where the crack is.

https://www.motor-bike-breakers.co.uk/wp-content/uploads/2014/11/Yamaha-Thundercat-YZF600-1998-Rear-View-600cc-Engine-Motor-Cycle-Breaking.jpg


@Pete, Never did find a solution for it, changed everything (coils, plugs, leads, caps). I can't hear it any more. I started wearing earplugs. Though last week I touched the cam cover and could still feel faint shocks like static electricity.
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yzf 600r