Stripped exhaust port thread

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70sbikes
Posts: 96
Joined: 13 Nov 2014 11:44
Location: Melbourne Australia

Stripped exhaust port thread

Post by 70sbikes »

My 1976 3 1/2 Sport has a stripped exhaust port thread. I'm after recommendations on who can fix this. I am in Australia, but I'm willing to post the cylinder head overseas.

Cheers

Trevor
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Stripped exhaust port thread

Post by MickeyMoto »

It may be cheaper to source a new head.
hendre
Posts: 600
Joined: 11 Aug 2007 06:51
Location: The Netherlands

Re: Stripped exhaust port thread

Post by hendre »

maybe you can show this vid to a local machine shop and they can solve it for you?
https://www.youtube.com/watch?v=ZfFbA9Y3jHw

the author of the video is on the forum (EVguru) and he may do it for you (did some in the past)
other adresses (from another topic):
https://www.lussoveloce.com/
https://www.morinispecial.it/joomla/ind ... cle&id=177
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Daddy Dom
Posts: 512
Joined: 16 Nov 2006 19:48
Location: Auckland, New Zealand

Re: Stripped exhaust port thread

Post by Daddy Dom »

Try Gary Jolly at Reliable Engineering in Adelaide.
DD
MRC 3082½
70sbikes
Posts: 96
Joined: 13 Nov 2014 11:44
Location: Melbourne Australia

Re: Stripped exhaust port thread

Post by 70sbikes »

It may be cheaper to source a new head
By "new" I assume you mean used? I thought about that, but I reckon there wouldn't be many used heads out there with pristine threads. The aluminium is now 45+ years old, and has been through countless heat cycles, meaning I'd probably end up back where I am now...
Try Gary Jolly at Reliable Engineering in Adelaide
I actually found another motorcycle engineering place in South Australia! I reckon Zuckerberg was listening in to my conversations, because this place popped up in my feed. I was scrolling through his posts, and the one that caught my eye was a Norton Commando head with beautiful bronze inserts. I spoke to him, and he has actually done Morini exhaust threads in the past. Heads are now boxed up and will be posted tomorrow. It's not going to be cheap, but given 3 1/2 Sports are fetching around $15,000 AUD, it will be worth it!
sheddweller
Posts: 48
Joined: 01 Aug 2010 16:28
Location: Sunshine Coast, Queensland, Australia.

Re: Stripped exhaust port thread

Post by sheddweller »

Would you mind posting some contacts for the engineering business in SA that has done inserts for Morini heads? I am in Queensland and have some damaged threads, as do at least 2 other local Morini owners. Thanks, Garry
70sbikes
Posts: 96
Joined: 13 Nov 2014 11:44
Location: Melbourne Australia

Re: Stripped exhaust port thread

Post by 70sbikes »

Martyn Adams at MDA Motorcycle Engineering.

https://www.facebook.com/search/top?q=m ... ngineering

martynadams.eng@gmail.com

0421 874 513

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With postage, it cost around $1,200 AUD. Before the naysayers reply with "The bronze inserts won't stay fixed in place", Martyn does the same work on Norton Commandos (and has done for many years), knows what he is doing, and has nothing but positive feedback on his work. He's a frickin' genius! Get it done before he retires or shuffles off the mortal coil!

Trevor
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Stripped exhaust port thread

Post by MickeyMoto »

That looks like a very nice job. Shame he is in Oz.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Stripped exhaust port thread

Post by norbert »

Sören the vikingo is doing the job as well (you´ll find it scroling down :wink: )

http://morinist.dk/morini/tyskdele.php
70sbikes
Posts: 96
Joined: 13 Nov 2014 11:44
Location: Melbourne Australia

Re: Stripped exhaust port thread

Post by 70sbikes »

I didn't mention that Martyn's inserts meant the "dome" in the exhaust port was machined off. To get the exhaust pipes to fit properly I had to grind away the taper on the half-rings. This took a while, as I didn't want to ruin the hard to obtain rings, so it was grind, check the fit, grind, check the fit, until they were perfect. Martyn also recommended using two exhaust gaskets.

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