Thread repairs

[Andy1976]

Hi all,
I've stripped 2 of the threads on my engine so as a result the rocker cover will not tighten down causing an oil leak.
Is using heli coils the correct way to go, and is it something I can do myself or do I need a motor engineer to do it?

Any advice is appreciated, as thread repairs is something I've never done.

Thanks
Andy

[mick]

Hi Andy i think you can diy and you can buy a kit but not sure where from hope fully someone else with better experience will chime in shortly  cheers Mick.

[Seamus]

Heli coil kits are easy to use. I have re threaded some for the same purpose as you.

Careful drilling of the hole and then tap for the insert (in the kit). Fit coil with the tool supplied and break off the tang. It is actually that simple. See http://www.fjr1300.info/howto/helicoil.html  for more detail.
There are different flavours of helicoil kit (recoil for example) Avoid the really cheap ones as they may not be so good.
Any good tool shop will sell you a kit. The kits come normally with everything for one size (eg M6).

A quick google will get you suppliers (example https://www.portlandtools.co.uk/Hand_tools/Thread_repair/ )

Good luck

Seamus

[Bryanj]

If its just the outer cover screw threads (rocker, points,clutch,etc) Helicoil is OK just need care and patience, if its a more stressed thread, like the cam bearing bolts/studs you need a "Keensert"

[Seamus]

Not heard of Keenserts before, but a google turned up http://www.specialty-fasteners.co.uk/updoc/Complete_Keensert_Catalogue_June_2008.pdf

[Bryanj]

Used Keenserts for years, they are way stronger than helicoils and easier to fit BUT do need plenty of surrounding metal as for 6mm stud/bolt you are tapping out to 10mm.

You need to be carefull wherever you fit inserts that if the hole is a "through" hole and the inside has liquid oil you can get an oil leak down the threads so the insert needs to have the outer threads sealed and prferably a stud inserted again with thread sealer

[Andy1976]

Thanks for the replies, I'm gonna have a go myself, so I've ordered the m6 helicoil kit from a local tool shop.

Andy

[Spitfire]

Just a thought, how bad are your threads, I cross threaded one of my rocker cover bolts changing them to Allen screws when the bike was new (1976 CB750F1), I got away with using a tap to re cut the threads and it's still OK now.

Cheers

Den

[Andy1976]

Hi Den, the threads are well mashed, I don't think re tapping will do it.

Andy

[hector2800]

don't try and tap the thread all at once turn the tap back a full turn every so often or it can jam and snap and then you're in to a completely different ball game. You may know this already but I thought I ought to mention it.