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Piston size

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Larry G
honda305.com Member
Posts: 30
Joined: Wed Mar 14, 2012 5:13 pm
Location: Arlington, Texas

Piston size

Post by Larry G » Sun Jun 17, 2012 12:42 am

Help! I need to buy new pistons for my cl77, motor was stuck, i did get the motor apart and media blasted the pistons, they have pits and not really knowing if they are still any good I have decided to have it bored over and install new pistons and rings, I have no way to measure the piston size so I looked in bill silvers book and it says to check the inside of the piston for the size or check the top of the rings, well, ring says .25 and all I see inside the piston is a small arrow and a 5. Nothing else, so I am not sure what size pistons to order..any ideas anyone?
1965 Honda cl-77
1986 klr 600

mike in idaho
honda305.com Member
Posts: 411
Joined: Sun Jan 29, 2012 9:18 pm
Location: orofino, idaho

Post by mike in idaho » Sun Jun 17, 2012 9:00 am

Any numbers on the underside of the piston will be casting numbers, not necessarilly finished size info. Unless some clown has filed down a set of oversize rings to fit a standard size barrel there should be a .25 stamped on top of the piston. Hone the barrel and see see what it measures for diameter. If it is within spec for size after honing the rust out , you may get by with just a new set of pistons.
'65 YG1
'65 CB160
'66 CL160
'66 CL77
'78 XS650
'79 GL1000
'69 T100R
'68 TR6
'69 T120
'72 750 Commando
my company car is a Kenworth

LOUD MOUSE
honda305.com Member
Posts: 7817
Joined: Mon Aug 15, 2005 8:23 am
Location: KERRVILLE, TEXAS

Re: Piston size

Post by LOUD MOUSE » Sun Jun 17, 2012 9:50 am

I believe you will find it is a 1st over (0.25) which should measure 60.25mm. ...........lm

Larry G wrote:Help! I need to buy new pistons for my cl77, motor was stuck, i did get the motor apart and media blasted the pistons, they have pits and not really knowing if they are still any good I have decided to have it bored over and install new pistons and rings, I have no way to measure the piston size so I looked in bill silvers book and it says to check the inside of the piston for the size or check the top of the rings, well, ring says .25 and all I see inside the piston is a small arrow and a 5. Nothing else, so I am not sure what size pistons to order..any ideas anyone?

Larry G
honda305.com Member
Posts: 30
Joined: Wed Mar 14, 2012 5:13 pm
Location: Arlington, Texas

Post by Larry G » Mon Jun 18, 2012 10:32 pm

Thanks for info, do you know where can buy new pistons and rings? Or does any one sell a kit?
Thanks
1965 Honda cl-77
1986 klr 600

voxa_33
honda305.com Member
Posts: 7
Joined: Mon Feb 06, 2012 12:46 am
Location: United States

Post by voxa_33 » Tue Jun 19, 2012 9:59 pm

Call this guy he may have. http://www.olypen.com/retro/

mike in idaho
honda305.com Member
Posts: 411
Joined: Sun Jan 29, 2012 9:18 pm
Location: orofino, idaho

Post by mike in idaho » Wed Jun 20, 2012 4:29 am

'65 YG1
'65 CB160
'66 CL160
'66 CL77
'78 XS650
'79 GL1000
'69 T100R
'68 TR6
'69 T120
'72 750 Commando
my company car is a Kenworth

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