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Hairline crack in crankcase

Posted: Fri Jul 31, 2015 12:00 pm
by tippo88
Just had the crankcase cleaned up and noticed small crack as per the pictures.
Doesn't seem to go all the way through the case but guess it's best to get welded ? Was just about to start the rebuild.

Thanks

Tippo
Imageng
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Re: Hairline crack in crankcase

Posted: Fri Jul 31, 2015 1:48 pm
by mick1
Had one very similar that caused an air leak and holed my piston.......a £300 lesson. get it welded and then pressure test when assembled.Image

Re: Hairline crack in crankcase

Posted: Fri Jul 31, 2015 5:29 pm
by tippo88
Thanks! Can get welded was thinking drill the end of the crack to stop spreading and then get welded . How would I pressure test when engine built ??

Cheers

Tippo


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Re: Hairline crack in crankcase

Posted: Fri Jul 31, 2015 6:15 pm
by mick1
A cheap method is to put a cut cycle inner tube over the inlet manifold (carb removed) and over the exhaust tail pipe. Inflate inner tube and spray cylinder and manifolds with soapy water. Watch for bubbles. Fit a pressure gauge on the valve and check the pressure doesn't drop.it doesn't need to be a massive pressure 5 psi would be ample, too much can damage the seals.

believe me it's not that easy :)

Sealing the inner tube will be the fun part and the exhaust may be a potential leak, but it should show any casing leaks.

Re: Hairline crack in crankcase

Posted: Fri Jul 31, 2015 7:08 pm
by dave411
Surely the worse that can happen is loose gearbox oil???
The crack is in the casing that the gearbox is in isnt it?

Re: Hairline crack in crankcase

Posted: Fri Jul 31, 2015 7:27 pm
by mick1
looks the case...... :oops:

tunnel vision with what happened to mine :?


JB Weld or similar would probably do the job.....

Re: Hairline crack in crankcase

Posted: Sat Aug 01, 2015 6:36 am
by tippo88
It is in the gearbox so no a big deal but one of the good things about living in Malaysia is the local workshops. Literally 5 mins and equivalent of 3 pounds later and it's all welded, just need to clean it up.
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Re: Hairline crack in crankcase

Posted: Sat Aug 01, 2015 7:16 am
by tippo88
Good as new [SMILING FACE WITH OPEN MOUTH]
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Re: Hairline crack in crankcase

Posted: Sat Aug 01, 2015 4:11 pm
by T5-190
Ha I lived in KL/ Malacca for about 6 months years ago, is your welder wearing flip-flops ? Ours used to turn up on site every day wearing them " no boots boss ". Nice repair by the way £ 3 well spent.

Re: Hairline crack in crankcase

Posted: Sun Aug 02, 2015 6:46 am
by tippo88
Yep flip-flips still very common in workshops and pretty much compulsory when riding !


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