Topic: welding a crank case? or replacement? help.

[kenneyginter]

hey guys new to the forums but starting up my first cafe project on a 1977 honda cb750f2. hit a snag and was hoping someone could help. when breaking down the engine i broke a engine bolt. in the process of drilling it out i broke off the hardened bit. great... anyways i finally drilled it out but made a mess. is it even savable? can i weld and retap? do i need to replace the case and if so where can i get one, just the lower half. are the all the same or do i need an f2 case.? sorry for all the question i could just use some help. pic below.

[KingCustomCycles.com]

It can be welded.  Ask around the local Harley and independant shops and see who they use for the work.  It will be much time and money saved over swapping cases and will not even be noticeable if done correctly.  It should cost you less than 50 bucks.

[Old Scrambler]

Inquire about a Time-Sert.  Its a very strong insert often used in aluminum blocks or heads. You will tap new threads. A good bike shop or a modern car dealership will know about them.  Only takes a few minutes........less than 1/2 hour.

If you end up needing a lower case, save the oil pan and any K case will work......but it won't be black. If you need a black case or complete set.......I have a spare lower to dismantle.

[bryanj]

DO NOT FIT ONLY THE LOWER CASE the cases are machined as pairs

[KingCustomCycles.com]

DO NOT FIT ONLY THE LOWER CASE the cases are machined as pairs

Yep, forgot that, Thanks!

[bryanj]

(1) time sert will fixit

(2) as its only one of the 6mm thread bolts it probably will be ok without it as long as the adjacent ones are OK

[mystic_1]

Looks to me like the bolt hole in question is one of the ones at the rear of the case, next to the kick start shaft, 6x40mm I believe.  I would personally totally go with a timesert or helicoil there.

mystic_1