Standard head gasket size- Pistons are 2mm O\S

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Timspu
Posts: 52
Joined: Fri Nov 18, 2005 10:59 pm
Location: Devon, UK

Standard head gasket size- Pistons are 2mm O\S

#1 Post by Timspu » Sat Apr 22, 2017 6:07 am

Gents,
After 10 years hidden in the garage I have dragged the LC out, After having started it I believe I have a head gasket leak on the rear left cylinder. Water in the exhaust pipe. The engine was bored out to 540 cc many moons ago so am trying to source a head gasket. I believe the bore will be 2mm O\S. Will a genuine gasket from Yamaha fit? Does anyone know the internal dimension of the head gasket?

Thanks
Tim
UK

Timspu
Posts: 52
Joined: Fri Nov 18, 2005 10:59 pm
Location: Devon, UK

Re: Standard head gasket size- Pistons are 2mm O\S

#2 Post by Timspu » Mon May 01, 2017 3:57 pm

I have pulled the rear cylinder head off and confirmed 2mm O\S pistons fitted. Will buy a genuine head gasket and measure it to see if it will fit. Will advise on measurements once received.

Timspu
Posts: 52
Joined: Fri Nov 18, 2005 10:59 pm
Location: Devon, UK

Re: Standard head gasket size- Pistons are 2mm O\S

#3 Post by Timspu » Thu May 04, 2017 2:44 pm

Genuine gasket arrived and the gasket measured 57.5 mm. My bore is 58mm.
What do you guys do in this situation. I believe I have two options, fit as is with a small difference or grind out to 58mm. Personally I think I could cause more issues by grinding the gasket possible causing it to leak.

begbie
Posts: 289
Joined: Fri Sep 02, 2011 7:02 pm
Location: UK

Re: Standard head gasket size- Pistons are 2mm O\S

#4 Post by begbie » Thu May 04, 2017 3:38 pm

If the installed pistons have a negative deck height of 0.3 mm you should be ok.

Timspu
Posts: 52
Joined: Fri Nov 18, 2005 10:59 pm
Location: Devon, UK

Re: Standard head gasket size- Pistons are 2mm O\S

#5 Post by Timspu » Fri May 05, 2017 3:35 am

Thanks for the info. Gasket and head installed.
Cheers

Tim

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