Heavy Twins

Could anybody tell me why my Dominator oil tank has got two breathers, and are they both necessary.

Hi folks, finally decided to join.
Went for a spin on my 57 Dommie 99 and within a few hundred yards got a graunching sound from below.

Hello,

After 6 months use I found a gradually worsening smell of petrol in the garage where I keep the Norton. The Bantam and the motor mower were innocent - there was a dampness under the Norton's tank towards the back.

What's the best way to check/set the ignition timing on a '61 99?

Evening. Hope someone can help as absolutely stuck. I am fitting the above to a Lucas SR1 magneto as coil is suspect.

Got the crank and new rods together at last and dry fitted in crankcases. I turned down an old Superblend and roller bearing to make assembly easier and now need to know about sorting the end float.

Hello

My 1962 650ss with a 99 barrel finally started the other day but sadly needed a bike starter to get her running.

Folks,
I want to change the rear mudguard on my Dommie.
A friend of mine has a spare mudguard from model 88 to give me.
Checking the spare parts list they have different part number.

What's the best way of checking that  the pressure plate comes off the plates squarely?