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M10 DOME Cylinder NUTS HEX

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mo goldie:
do anyone know what the thread is on the cylinder head on the black bomber...... as trying to get some to replace the old rusted  steel domed Nuts with stainless steel ones ?

I got 8 domed ones and they don't fit seems as if they are a more of course thread as I tried one and it wanted to cut a new thread so must be some other thread on the studs. if it is the ones I got they only seem to do one size of thread on Ebay so if you know where I can get some would be great help.


Depends on the age of the bike. Threads changed around 1966-67.

Most M10 nuts you find in the UK are 1.50 pitch, Honda used 1.25 pitch after 1967 ish. Also called metric fine.

Something like these may do.

M10 x 1.5

If that’s so Ash, then why does he say the nuts he bought have a rougher thread than the studs.?

I’m not sure what the bomber uses as I’ve never worked on one or owned one, my reply was pure logic, if the nuts he bought had a coarser thread then the studs must be metric fine and an M10 metric fine is 1.25. My logic wrong?

I have to go with Ken on this one, OP says those nuts he bought are coarser, not finer and I have never seen or heard of an M10 coarser than 1.5mm pitch, only the 1.25mm finer version.  The domed rear damper top nuts on 350,400 and 550 fours are M10x 1.25 - I have some in stainless.  It wouldn't make engineering sense to clamp a cylinder head down with coarse threads where the wedge angle is greater and more prone to loosening.  I've never worked on a Bomber either and I've been wrong before though - just ask Christine 🤓


Just a thought - the stainless ones I bought are next size up across the flats compared with Honda - check there is clearance for your application.


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