atocp Posted June 29, 2012 Share Posted June 29, 2012 Hi all, I posted a couple of years ago about an engine block that I had stripped the threads off where the stud goes in. I repaired it using Epoxy Steel Weld (which was amazing, actually took 2 mole grips, a stud extractor, 50cm lever and a blowtorch to remove!!). However, I have decided to replace the studs and need to drill out and put in a Heli-Coil thread repair. My problem is this....using a digital calliper, I measured the diameter of the stud as 6.25mm. The diameter of the threaded ends was ~6.7mm. I didn't measure the pitch. I can't use an M6 helicoil because it'll be too tight. What size should I be looking for, as Heli-coil's seem to come in the metric M5, M6, M7 sizes, and don't really cover the 6.25mm or 6.7mm size that this stud seems to be. In fairness, the epoxy weld was sooooopper strong, so it's still a last resort, but i'd rather use a tap and die set and repair the thread. Many thanks for any help you can give me on this. Bit by bit, im slowly getting there. Thanks, atocp Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 29, 2012 Moderator Share Posted June 29, 2012 most likely an M7 stud then eh? wemoto will sell them Link to comment Share on other sites More sharing options...
atocp Posted June 29, 2012 Author Share Posted June 29, 2012 Hey Airhead, thanks for the reply. can you not get sizes in between for any kind of thread repairs? what happens when you can't accept a tolerance of something between say an M6 and an M7, is there another way to fix a thread like this when you are stuck with a specific stud size? many thanks again, atocp Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 30, 2012 Moderator Share Posted June 30, 2012 I just think your stud size will be 7mm, it's no surprise to me that you measure the thread diameter at 6.7mm. is it an exhaust stud?...you didnt say Link to comment Share on other sites More sharing options...
atocp Posted June 30, 2012 Author Share Posted June 30, 2012 Thanks again Airhead. I'll buy some M7 helicoils and give it a go. The worst that can happen is im left using the epoxy weld, which was crazily strong first time round. It was the 4 cylinder head studs on the YB100 that i was having problems with. Cheers again, atocp Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 30, 2012 Moderator Share Posted June 30, 2012 do you know the part number of the stud? this will give an idea of the size Link to comment Share on other sites More sharing options...
atocp Posted June 30, 2012 Author Share Posted June 30, 2012 i tried that, but unfortunately it didn't really suggest a size. Yamaha-90116-07035. M080731Y. But i checked the schematic and it didn't reveal any extra info. I'll pop onto ebay and get some M7's and give it a go. Thanks again, atocp Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 30, 2012 Moderator Share Posted June 30, 2012 i tried that, but unfortunately it didn't really suggest a size. Yamaha-90116-07035. M080731Y. But i checked the schematic and it didn't reveal any extra info. I'll pop onto ebay and get some M7's and give it a go. Thanks again, atocp It is 7mm then see what i highlighted... Link to comment Share on other sites More sharing options...
atocp Posted June 30, 2012 Author Share Posted June 30, 2012 i tried that, but unfortunately it didn't really suggest a size. Yamaha-90116-07035. M080731Y. But i checked the schematic and it didn't reveal any extra info. I'll pop onto ebay and get some M7's and give it a go. Thanks again, atocp here's me thinking it was 6.7mm......see what i highlighted... haha. i've just bought the (extremely hard to get hold of) M7 kit, i'll let you know how it all goes. atocp Link to comment Share on other sites More sharing options...
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