86mm ducati piston.

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david.anderson
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86mm ducati piston.

Postby david.anderson » Fri Feb 17, 2017 8:47 am

Can anyone help with some dimensions from an 860 GT Ducati piston. I just need the pin diameter, distance from the top of pin to top of piston outer edge, and from top of pin to crown. The 860 piston and the 450 Ducati may be the same piston so the dimensions of the 450 duc piston would also do.
or if anyone can give dimensions on a similar 86mm piston.
thanks
David

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Re: 86mm ducati piston.

Postby nevhunter » Sat Feb 18, 2017 1:09 am

The pin dia is 20 mm. Measured from a rod . A commonly used piston around that bore size fits Vincents. Nev

david.anderson
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Re: 86mm ducati piston.

Postby david.anderson » Sat Feb 18, 2017 9:05 am

Nev
thanks. while it appears the 860 duc used 450 duc pistons, the 450 looks like it has a 22mm pin. The 860 piston may be more suitable in a short stroke VH 86mm bore. Now I just need the height from the top of the pin to the top of the piston at the side and centre and hopefully with minimal machining it will fit.
JP no longer do one off pistons, even though they state otherwise on their web site.
Precision pistons in Melbourne want $700 for a one of, so I am looking for a substitute that I can adapt.
David

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Re: 86mm ducati piston.

Postby klaus gerhard » Sat Feb 18, 2017 10:27 am

Hello David
is this what you are looking for?
https://www.ebay-kleinanzeigen.de/s-anz ... 0-306-4697

Might be just the right pair for you?

Let me know if I can help!

Regards
Klaus

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Re: 86mm ducati piston.

Postby john.whiting » Sat Feb 18, 2017 12:26 pm

Yes,20mm pin,deck ht is 36.7mm.AE,possibly forged looking at internal machining.I picked up a couple thinking they could be ok in a Panther.Came from a MHR owner.When i asked why he replaced new looking pistons,he made some very rude comments on the relative merits of a Ducati and .............Regards John.

john.whiting
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Re: 86mm ducati piston.

Postby john.whiting » Sat Feb 18, 2017 12:35 pm

And outer edge is 31.7mm.Regards John.

john.whiting
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Re: 86mm ducati piston.

Postby john.whiting » Sat Feb 18, 2017 12:37 pm

And outer edge is 31.7mm.Regards John.

david.anderson
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Re: 86mm ducati piston.

Postby david.anderson » Sun Feb 19, 2017 8:47 am

Klaus, thankyou very much but the pistons are readily available here.
John, thankyou. Can you clarify if the heights that you quoted are from gudgeon pin centre (true deck height) or from the top of the gudgeon.
It is clear that the valve cut out will have to be milled outward so it looks like I will be taking a trip to Gosford where I can check the pistons against an original and see that there is enough meat for the machining necessary.
David

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Re: 86mm ducati piston.

Postby john.whiting » Sun Feb 19, 2017 9:41 am

Approx deck height from pin centre.Looks like about 10mm thick in central region where AE is branded.When i checked the Sporty piston ,it was simpler to bandsaw one in half.Watch out for cast in inserts though.Regards John.

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Re: 86mm ducati piston.

Postby david.anderson » Tue Feb 21, 2017 6:30 am

John
Thankyou very much. Those figures are very close to the 7.5 VH piston heights so compression ratio is probably similar. I will possibly look to a higher com 860 duc piston and adjust the piston or cylinder a little from there as I am looking for about 9 or 9.5 to 1.
David


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