Ariel Owners Motorcycle Club

I decided to remove the heads from my leader to check their state of carbon build up (which as it happens was perfectly clear) I noticed that there were 2 head gaskets fitted to each cylinder Is this a mod or did the previous owner not realise that there were 2 gaskets . The heads are the higher compression ones can anyone advise me please

hi, it may been done to lower the compression it may be the heads have been skimmed

Remachine the combustion chambers if contact is likely. Check with Plasticene. rather that HAVE 2 Gaskets which introduces an Unreliability factor you don't need. Some alloy 2s heads don't use a gasket at all, giving better heat conductivity. Nev

I usually check the "squish" gap between piston crown and head, with 2mm soft solder wire, after the head is bolted down.
Cut into a 3 inch length and make an L shape out of it, making sure the bottom of the L shape is about half of the dia of the piston, so 23mm should be fine. remove spark plugs and make sure piston is at bottom end of barrel. Insert wire , dont let go of the other end! across the piston 3 0 clock to the front of the engine, hand operate the kick start and let the piston come to TDC, IT SHOULD COMPRESS THE SOLDER. Remove and measure compressed solder, repeat at 9 O clock position and take a measurement again. Add up the 2 measurements and divide by 2. This is your squish.
People run different squish clearances dependant on fuel types and performance needs but about 1.5mm is usually good as a street machine.
DO NOT measure squish at front and rear of piston as the piston will rock forward and backwards on the bearing and will not give you an accurate reading.

If you need more revs then open the squish up a little to 2mm, more power (up to a point), reduce squish!