Chain cracked engine case. How to fix?

[RangaBlitzFanga]

Chain was a bit too loose, saw it earlier and thought "Hope that doesn't come off..." sure enough it came off, doubled up around the front sprocket and jammed against the casing, fortunately it's only a very small crack, maybe 8mm long and 1-2mm wide. Everything else still ok, started it to get it up the last bit of hill

What can I use to fix it? Since its so small would gasket sealant do the trick or is it likely to blow out and leak?
No cheap access to a welder

 

[timeeh]

Try this
http://www.selleys.com.au/putty/epoxy/knead-it-steel
Another member put me onto this recently as i am a spastic when using cutting discs.... Worked a treat

 

[RangaBlitzFanga]

ah yep I know the stuff, know someone who use a crushed coke can and that to fix a smashed transfer case on a 4x4. Worked for a few thousand K's at least

 

[my67xr]

if it is just the magneto cover then sealant will do the trick, it's only to keep water out of the electrics.
there is no oil behind it.
tif it's the l/h engine case behind the sprocket then do as above.
degease it well, rough it up with some coarse sandpaper and use the Knead-it/kwik steel, or even some devcon epoxy to seal it up again



you are lucky it didnt do more damage,
most of the time when the chain lets go, they snap off the mount and the pickup coil off the side of the stator, this means replacing the stator

i would be replacing the chain with a good quality one asap, and remember to adjust it up again too after a couple of rides, as they do stretch a little.

 

[rotn50]

I think ranga is riding a 250 vertical motor, if that's the case I'm pretty sure there maybe oil in the magneto, not sure if this is different on pushrod to non-pushrod and electric start or kickstart only donks but it is only some and not all, the watercooled 250 electric starts at work defianatly have oil in the magneto case. Is it a vertical or horizontal motor mate.

 

[RangaBlitzFanga]

it is definately to keep oil in. The crack is higher than the normal oil level so it doesn't leak when sitting but it did spew oil when starting it back up. This one is a vertical aircooled 250
Havn't got the cover off yet but it looks a little worse than I first thought. Like the chain has essentially pushed the edge of the side cover inward so it doesn't line up to the crankcase any more. I don't think it'll be a big problem, bend/break off the bad section, replace some metal parts in position and seal it all up with that putty metal

 

[RangaBlitzFanga]

don't suppose anyone has a manual for the Zongshen 250cc aircooled vertical? think its a CG250
Side cover doesn't want to budge, want to make sure i'm not missing a bolt somewhere

 

[rotn50]

Did you get the bolt in where the starter cogs go.

 

[RangaBlitzFanga]

missed it at first but yes got it. Side cover is off and oh dear....
So the affected area is rather large, about half a business card. Fortunately its entirely on the cover side, not the actual crankcase

It broke 3 sections that bowed inwards, making it look like a small crack at first. I tried tapping them straight but of course they broke, no biggie, plus if they won't bend back they just won't work. I broke off a small section and took to all 3 main pieces with a dremel. They sit sort of straight. Applied the selleys knead it steel stuff which is a massive PITA to work with as all it wants to do is stick to my gloves, not the steel. It dries too quickly and i've had to go at it 3 times and made a hell of a mess. Nevertheless i'm confident it'll seal, i'll finish it off tonight and dremel it smooth. I'm just hoping it mates with the crankcase correctly, if not then hmm... Suppose i'll have to get at it with the cutting wheel and start again

Will be posting pics tonight

 

[RangaBlitzFanga]

So this is how it looked after I broke the center piece out to allow the other 3 a bit of movement

pretty nasty. I could only see the center crack until removed from the case

First attempt at fixing them in place (mega bodgy)

And they were in the wrong place. Should of actually looked at the crankcase instead of going off their 'feels good' position :action-smiley-003: Took me another hour to grind most of it back and then cut out the 2 top pieces. Left the bottom one cause I couldn't be assed, and it doesn't interfere with anything anyway

2nd attempt...

Not pretty, but better than before. Lip/edge is not even from both the shards sitting slightly crooked, and the putty. Grind it all smooth...

There's a bit of a lip I will admit, but that's an easy fix if ever needed. All i'd have to do is smear more on the outside then grind it flat and level out the inside.
Most importantly the sealing edge is pretty damn close

And no leaks!

Never used a dremel or the metal putty before, I think it worked out ok considering the size of the damage. All up it set me back about $60 and about 4 hours to disassemble, patch, cut, re-patch, clean and reassemble. Not something I look forward to doing again but at least I know it can be done

 

[timeeh]

Practice makes perfect Looks like she'll hold up for a bit longer.