OK, we have all done it, and we have all found to our shame that someone else has done it!
Stripped a thread.
Doesnt matter if this is on a bike, a car, its a nightmare if it happens to you, and there is only one real way of fixing the issue – Helicoils.
In this example we have got a stripped thread on a scooter, its an M6 bolt that goesin to the engine and holds the variator case on. To start with though, lets have a look at the Helicoil kit.

As you can see the kit has everything we need to do the job.
- A drill
- A tap
- A tap wrench
- The helicoils
- The insertion tool and the punch out tool.
So whats first?
Using the drill that came with the kit:

Its a 6.3mm drill bit, as the hole has to be a little larger than the actual thread, so you want to ONLY use the supplied bit with the kit as a 6mm one wont work.
Drill out the stripped thread:

Be careful to only go as deep as the original hole. Once done get an airline and blow the hole out so its nice and clean.
Now, fit the M6 tap into the tap wrench. CAREFULLY start winding the tap into the hole, it will start to cut a new thread. In alloy you can just keep turning it in (use a little WD40 to assist you), but with steel, for every full turn in, wind it back out a 1/2 turn to clear any swarf.

Only go as far as the tool, dont force it further, cos if you break the tap in the hole you will have a real issue trying to get it out again. Once its tapped, wind the tap back out of the hole and check the thread, you should have a nice clean new thread in there.

Now, fit a new helicoil to the helicoil insertion tool. It has a little tang on the end of it that goes into the hole first.

Carefully wind the helicoil into the new thread. It want to be a little bit inside the hole, but only by a mill or so. Then withdraw the tool.

You see the nice new thread in the hole now.
Now, put the punch out tool into the hole and give it a whack with a mallet or hammer.

This will knock the tang off the inside of the helicoil. Use an airline to get it out of the hole.
Thats it, you now have a thread thats actually stronger than the original one was.
These kits are pretty cheap, about 15 quid off ebay, but well worth having the ones you need if you do a lot of work on your bikes. I would also recommend anyone to invest in an airline and compressor, you can get good cheap ones from wolfonline.co.uk