Author Topic: Desperately need piston rings for 78.5 mm piston  (Read 3005 times)

hugger

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Desperately need piston rings for 78.5 mm piston
« on: January 19, 2011, 04:47:07 PM »
Hi all,

First time poster and new FL350R owner. The buggy is in great shape over all, did a compression test and got ~120 PSI. Took off the head and the bore is perfect, shiny but near zero wear. I have been reading all about the history of the pistons and over heating problems.

My goal - if at all possible - is to deglaze and use a new piston with new rings.

Am I out to lunch or is there any chance that someone will have some parts I could buy?

Thanks
Hugger

hoodlum

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Re: Desperately need piston rings for 78.5 mm piston
« Reply #1 on: January 19, 2011, 07:02:35 PM »
Quote from: "hugger"
Hi all,

First time poster and new FL350R owner. The buggy is in great shape over all, did a compression test and got ~120 PSI. Took off the head and the bore is perfect, shiny but near zero wear. I have been reading all about the history of the pistons and over heating problems.

My goal - if at all possible - is to deglaze and use a new piston with new rings.

Am I out to lunch or is there any chance that someone will have some parts I could buy?

Thanks
Hugger



Wiseco sells them every day....You will need to run a bit more clearance than the stock piston though....Give it .005 clearance and you shouldn't have any problems as long as it is jetted correctly....
Hoodlum

hugger

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Re: Desperately need piston rings for 78.5 mm piston
« Reply #2 on: January 20, 2011, 05:23:43 PM »
Quote from: "Hoodlum"
Quote from: "hugger"
Hi all,

First time poster and new FL350R owner. The buggy is in great shape over all, did a compression test and got ~120 PSI. Took off the head and the bore is perfect, shiny but near zero wear. I have been reading all about the history of the pistons and over heating problems.

My goal - if at all possible - is to deglaze and use a new piston with new rings.

Am I out to lunch or is there any chance that someone will have some parts I could buy?

Thanks
Hugger



Wiseco sells them every day....You will need to run a bit more clearance than the stock piston though....Give it .005 clearance and you shouldn't have any problems as long as it is jetted correctly....
Hoodlum


Actually Weisco doesn't sell a 78.5mm piston, the smallest is 80mm.

hoodlum

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Re: Desperately need piston rings for 78.5 mm piston
« Reply #3 on: January 20, 2011, 05:32:29 PM »
Quote from: "hugger"
Quote from: "Hoodlum"
Quote from: "hugger"
Hi all,

First time poster and new FL350R owner. The buggy is in great shape over all, did a compression test and got ~120 PSI. Took off the head and the bore is perfect, shiny but near zero wear. I have been reading all about the history of the pistons and over heating problems.

My goal - if at all possible - is to deglaze and use a new piston with new rings.

Am I out to lunch or is there any chance that someone will have some parts I could buy?

Thanks
Hugger



Wiseco sells them every day....You will need to run a bit more clearance than the stock piston though....Give it .005 clearance and you shouldn't have any problems as long as it is jetted correctly....
Hoodlum


Actually Weisco doesn't sell a 78.5mm piston, the smallest is 80mm.



Thought stock was 80mm.....I stand corrected.....Try these if your piston is still good....
http://cgi.ebay.com/ebaymotors/NOS-Honda-Piston-Ring-STD-85-FL350-Odysey-13011-VM0-681-_W0QQcmdZViewItemQQhashZitem43a3818472QQitemZ290505983090QQptZMotorcyclesQ5fPartsQ5fAccessories
If not,it may be well worth the money to buy a 80mm piston and have it bored opposed to paying for a stock piston if you can even find one....

hugger

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Re: Desperately need piston rings for 78.5 mm piston
« Reply #4 on: January 21, 2011, 06:51:21 PM »
Actually Weisco doesn't sell a 78.5mm piston, the smallest is 80mm.[/quote]


Thought stock was 80mm.....I stand corrected.....Try these if your piston is still good....
http://cgi.ebay.com/ebaymotors/NOS-Honda-Piston-Ring-STD-85-FL350-Odysey-13011-VM0-681-_W0QQcmdZViewItemQQhashZitem43a3818472QQitemZ290505983090QQptZMotorcyclesQ5fPartsQ5fAccessories
If not,it may be well worth the money to buy a 80mm piston and have it bored opposed to paying for a stock piston if you can even find one....[/quote]

Thanks Hoodlum - I may be over thinking this but I'm thinking that if I go back to an 80mm bore then I should consider a water cooled head - after all that's why Honda went from 80 down to 78.5. I assume they did is to increase the thickness and strength of the exhaust port divider.

A water cooled head might be a good mod anyways!

hoodlum

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Re: Desperately need piston rings for 78.5 mm piston
« Reply #5 on: January 22, 2011, 11:17:23 AM »
Quote from: "hugger"
Actually Weisco doesn't sell a 78.5mm piston, the smallest is 80mm.



Thought stock was 80mm.....I stand corrected.....Try these if your piston is still good....
http://cgi.ebay.com/ebaymotors/NOS-Honda-Piston-Ring-STD-85-FL350-Odysey-13011-VM0-681-_W0QQcmdZViewItemQQhashZitem43a3818472QQitemZ290505983090QQptZMotorcyclesQ5fPartsQ5fAccessories
If not,it may be well worth the money to buy a 80mm piston and have it bored opposed to paying for a stock piston if you can even find one....[/quote]

Thanks Hoodlum - I may be over thinking this but I'm thinking that if I go back to an 80mm bore then I should consider a water cooled head - after all that's why Honda went from 80 down to 78.5. I assume they did is to increase the thickness and strength of the exhaust port divider.

A water cooled head might be a good mod anyways![/quote]

WC head will not cool the exhaust bridge....When it is bored,the bridge needs to be relieved a couple of thousands,and holes need to be drilled in the piston to allow cooling of the bridge...There are instructions included with the piston for doing this....They dropped to 78.5mm to give more metal and better heat displacement,but there aren't very many running around now with that size bore....
Just make sure you leave enough piston/cylinder clearance and you should be fine....DO NOT go by what is on the box or it will sieze....Leave a minimum of .005" clearance.....I actually ran one a couple of years with .007 clearance without issues....Not condoning it,just saying what I have experienced...I have also heard of people running as much as .009",but I have never done it..It had a little slap until it warmed up,but that was all....If you are jetting for optimal performance,then leave more clearance....If you are planning to run it on the rich side,.005" should be plenty....Make sure also that the ports are chamfered correctly,or that exhaust bridge will snag a ring.....
Hoodlum

hugger

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Re: Desperately need piston rings for 78.5 mm piston
« Reply #6 on: January 24, 2011, 01:54:37 PM »
Quote from: "Hoodlum"
Quote from: "hugger"
Actually Weisco doesn't sell a 78.5mm piston, the smallest is 80mm.



Thought stock was 80mm.....I stand corrected.....Try these if your piston is still good....
http://cgi.ebay.com/ebaymotors/NOS-Honda-Piston-Ring-STD-85-FL350-Odysey-13011-VM0-681-_W0QQcmdZViewItemQQhashZitem43a3818472QQitemZ290505983090QQptZMotorcyclesQ5fPartsQ5fAccessories
If not,it may be well worth the money to buy a 80mm piston and have it bored opposed to paying for a stock piston if you can even find one....


Thanks Hoodlum - I may be over thinking this but I'm thinking that if I go back to an 80mm bore then I should consider a water cooled head - after all that's why Honda went from 80 down to 78.5. I assume they did is to increase the thickness and strength of the exhaust port divider.

A water cooled head might be a good mod anyways![/quote]

WC head will not cool the exhaust bridge....When it is bored,the bridge needs to be relieved a couple of thousands,and holes need to be drilled in the piston to allow cooling of the bridge...There are instructions included with the piston for doing this....They dropped to 78.5mm to give more metal and better heat displacement,but there aren't very many running around now with that size bore....
Just make sure you leave enough piston/cylinder clearance and you should be fine....DO NOT go by what is on the box or it will sieze....Leave a minimum of .005" clearance.....I actually ran one a couple of years with .007 clearance without issues....Not condoning it,just saying what I have experienced...I have also heard of people running as much as .009",but I have never done it..It had a little slap until it warmed up,but that was all....If you are jetting for optimal performance,then leave more clearance....If you are planning to run it on the rich side,.005" should be plenty....Make sure also that the ports are chamfered correctly,or that exhaust bridge will snag a ring.....
Hoodlum[/quote]
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Thanks for the help, I'll post on the board once it's running.
Hugger