GS750es 1985 : Wrong Wiseco pistons kit

[dpascal]

I bought the Wiseco 816 cc kit for my GS750ES 1985 3 years ago in a shop in the US. I can't remember which shop was it but it was a certified Wiseco dealer.
Today after I finished restoring the entire bike, I sat down to assemble the restored part of the engine.
To my amaze I found out that the seller gave me Wiseco pistons for GS750 1977 844cc and I was idiot enough not to verify what I got.
I even went to an engine shop and and had my cylinders drilled to fit the GS750 1977 kit.
The good news in this horrible story is that the bore of the GS750 1977 844cc kit is 69mm and this still leaves me 1mm to drill for the GS750ES 1985 816cc which has a bore of 70mm.
Any ideas if Wiseco will enable me to send the GS750ES 1977 kit and have it replaced with a GS750ES 1983-85 ?

Link to to the GS750 1977 844cc kit :
http://www.wiseco.com/ProductDetail.aspx?ItemID=4035M06900&ModelID=549&ModelYear=1977&AppID=7461
Link to to the GS750ES 1985 816cc :
http://www.wiseco.com/ProductDetail.aspx?ItemID=4188M07000&ModelID=551&ModelYear=1983&AppID=7465

Photos of my restoration:
https://drive.google.com/drive/folders/0B9qq4FZhlJ3dSElTRHNhZ0U4YUU?usp=sharing

 

[dpascal]

Wiseco just told me that since the pistons kit was not bought directly from them, they cannot replace it
Any recommendations on other Aftermarket piston brands ? Maybe ones that do custom sizes so I can keep my current bore of 69 mm...

 

[Guest]

Wow! That's too bad. Maybe sell your incorrect set in the parts for sale section? I think JE Pistons may still sell GS replacements. Good luck.


You might look for your transaction on line. I have been surprised by some of my eBay and amazon purchases and have been able to go back a couple years to find the sellers info., just an idea.

 

[dpascal]

I just sent JE pistons an email. Asked for the price of a custom order so I can keep my 69mm bore size.
I also posted an ad in the parts for sale.

 

[dpascal]

I was able to lay a hand on a NOS Yoshimura 816cc 4 pistons kit for the 1983 GS750ES.
Strangely it has 4 rings for each piston.
Thinking it's probably a faulty packaging I went to ebay to order a ring set and found one that also comes with 4 rings.
I contacted the seller who confirmed that the ring set he sells has 4 rings in it.
Any idea why ?

http://www.ebay.com/itm/YOSHIMURA-S...ash=item25be380f81:g:9hgAAOxy~ilSOz39&vxp=mtr

 

[Agemax]

where do you see 4 rings? there is only 2, even states it in the listing. 1 x compression ring and 1 x oil control ring (which is made up of 3 parts)

 

[dpascal]

I'll rephrase ...
Instead of 2 compression rings and one oil ring (composed of 3 parts) the set has only 1 compression ring and one oil ring (composed of 3 parts).
This doesn't make sense because as you can see in the attached picture, the Yushimura piston has 2 grooves for 2 compression rings.
Looks like all the ring sets for Yushimura that I came across are missing a compression ring ...

 

[dpascal]

Mystery solved ...
The Yoshimura kit that was given to me contains 3 pistons with 1 compression ring and 1 bastard piston (slightly lighter and fatter) with 2 compression rings.
I ended up with 4 beautiful man cave ash trays ...
For crying out lout ! Do I carry a "screw me up!" sign on my forehead ?! :-&

 

[Guest]

The Wiseco 816 kit is still available. http://gszone.biz/pistons.html

 

[dpascal]

A friend told me that the Wiseco kits are not as durable as CP pistons or JE pistons.
Is that right ? What is the experience of people here with Wiseco kits ?