Author Topic: Damage to alternator cover and crankcase . . .  (Read 674 times)

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Offline slkern

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Damage to alternator cover and crankcase . . .
« on: April 04, 2014, 07:59:38 PM »
If you look at the images I attached, there's some damage to a couple screw holes on my alternator cover and crankcase.  I was just wondering how to go about repairing something like that?  Is it even repairable or would I need a whole new cover and crankcase?

Thanks,
-- Samuel K.
'72 CB750 K2

Offline grcamna2

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Re: Damage to alternator cover and crankcase . . .
« Reply #1 on: April 04, 2014, 08:04:58 PM »
The pictures won't let me click on them but it looks like the crankcase threads there had been somewhat repaired? The Alt. cover can be fixed w/ strong epoxy or JB Weld around the edges of that hole possibly.
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline calj737

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Re: Damage to alternator cover and crankcase . . .
« Reply #2 on: April 05, 2014, 05:54:15 AM »
On the engine side, run a thread tap in there using lots of cutting fluid. 1/2 turn in, 1/2 turn out as you go. This properly removes the cut shavings and cleanly re-cuts the threads.

As for the cover side, it's cosmetic only. If you're painting the covers, JB Weld or epoxy will fit it. If your power coating or polishing, then use a TIG and weld some fill back in, file and shape to smooth.
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Offline grcamna2

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Re: Damage to alternator cover and crankcase . . .
« Reply #3 on: April 05, 2014, 06:04:36 AM »
On the engine side, run a thread tap in there using lots of cutting fluid. 1/2 turn in, 1/2 turn out as you go. This properly removes the cut shavings and cleanly re-cuts the threads.

As for the cover side, it's cosmetic only. If you're painting the covers, JB Weld or epoxy will fit it. If your power coating or polishing, then use a TIG and weld some fill back in, file and shape to smooth.

+1  and use a small SS washer under a SS allen bolt,buy the Stainless Steel allen bolt kit for the engine,it'll really dress it up & you'll never have to use an impact screwdriver on that side cover again.
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Don R

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Re: Damage to alternator cover and crankcase . . .
« Reply #4 on: April 05, 2014, 08:36:24 AM »
 Is there a helicoil in the case hole? If so don't tap it. If it holds a bolt fine, if not use a helicoil or a timesert to repair the threads.  Find the longest bolt that does not bottom out, there may be more threads further in too.
As posted, the cover can be repaired or replaced at your choice.
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Offline grcamna2

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Re: Damage to alternator cover and crankcase . . .
« Reply #5 on: April 05, 2014, 08:56:11 AM »
Flush the hole in the crankcase out real good w/ a(WD40?)spray of some type and then take a close up picture and show us more.
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.