Hitchcocks Forum

I have a 2003 500 Bullet Classic. Can anyone tell me if the the decom thread is the same as the spark plug thread. If so will a spark plug thread repair kit do for the decom thread too?

It must be the same because people sometimes run them on twin plugs.

Yes indeed, the thread is 14x1.25mm. Note the thread on the end of the valve is quite short, similar to a short reach spark plug, so a shorter repair insert will do.

Inserts are available either as helicoils (springs) or solid.

A.

Thanks Stinkwheel and Adrian. I`ve never been able to stop this thing leaking. It seems to undo itself and leak, so I tighten it up and over time have stretched the threads a bit. Time to look for some inserts.

Plenty of suppliers around for this sort of kit, including our hosts' accessory catalogue item number 98355.

A.

Ivor wrote: ↑

Sun Feb 21, 2021 6:14 pm

Thanks Stinkwheel and Adrian. I`ve never been able to stop this thing leaking. It seems to undo itself and leak, so I tighten it up and over time have stretched the threads a bit. Time to look for some inserts.

Has it got both washers in? They are big fat copper washers of two different diameters with a round cross section when you first get them and they squash into place. I'd be surprised if those leaked but not surprised if it leaked after being reasembled with old ones. They look flat when removed so you might not realise how they came. (part 90122)


Also, is it leaking round the base or simply the valve stem?

stinkwheel wrote: ↑

Sat Feb 20, 2021 3:56 pm

It must be the same because people sometimes run them on twin plugs.

Is this a simple matter of joining up two HT leads together? What are the pros and cons?

Please ignore my question, I've just read up on how to fit the extra plug. I'll save it for another day.