A Thread thread ! (Help needed)

Texas KZ, 75mm????? That cant be right,that would put the end of the bolt right inside the crankcase somewhere on a line with the camchain!
Good to know about the bottoming tap.My standard taps are a lot more direct with a lot less lead in but they are sized for standard thread sizes.I think my Helicoil tap is an odd size. 6.3mm or something like that.Ill have a look see.

OnkelB wrote:

davido wrote: Could do but it would be a lot easier if someone just measured it and said,'This hole should be xxxmm deep'

Guess what, I just tore my spare J (GPz 1100) engine down this weekend - went out and measured, that hole is 22 mm deep.

And yes, the two locator dowels for the sprocket cover are on the bottom bolts, none in the hole in question.

BINGO!!! Thank you OnkelB. That sounds a lot more like it.Thank you and thanks to everyone else for trying. Now I have something to work with.
Swest,youve given me an idea. Why the drill isnt going in further than 10mm. Not because theres a locating dowel but maybe the remnants of the original bolt. I didnt consider that. Im going to have a look. Thanks again,Great site this.
Ill post the outcome.

:blush: :blush: :blush:

Read the wrong scale on the caliper, duh!

Just a skosh over 22.

No problem, happy to help.

Btw, it would be a good idea to put some kind of stop or at least a marking on the drill - if you drill much over 25 mm in you're getting very close to going through.

On the drilling question only......perhaps using an endmill will help with getting the hole perpendicular as regular drill bits bend.

Bluezbike,on the question of an endmill, Ive no idea what that is and I dont have one. I did manage to get a couple of very overlong (good qulity)drills today and some aluminium rod. So the idea remains to drill out the hole to 20mm+-deep ,Tap it,insert a bit of threaded 8mm aluminium rod,Replace the cover,drill a centered dimple in it,take off the cover and drill it out all the way for an M6 thread. Bobs your uncle and Fannys your aunt!
Ive got a quiet work week this week so Ill try and get it done in the next couple of days.I will post on the result,whatever it is

At this point I think it would be better to have it fill welded and start over.
Steve

No no no. Way too much hassle . Thats the very very last resort . After the last resort has closed for the winter and all the guests have gone home. The water and power have been turned off and the first flakes of snow have started to fall, I would still try glueing the little bugger in first!!!

I am as confident as can be that this will work though.Stay tuned.