Holy Grail of XS400 Big Bore Pistons

Hey man I think the fj1200 and 1300 rod (36y) rod is the same dimensions as the xjr rod (5EA). the fj rods are a littler weaker and heavier, but They'll still be plenty for our motors and can be found more easily.


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I ended up getting a FJ rod off of ebay but couldn't do anything with it. Seller failed to disclose that it was bent. My motor is back together so I can ride this bike at least once this year. Over the winter I'll try to get a junk motor to test around with.
To update to this. Crazypj mentioned on another thread that xs650 liners and gsxr1100 78mm pistons would be able to fit. If thats true then we would have a 501cc engine. But later I believe he went on to use gs500 liners and pistons. Gs500 uses an 18mm wrist pin with a 26mm crown height.

Im hunting as well..
I decided to just buy sanglas pistons for mine, no mods needed and a good price. They aren't big bore, but do add compression with a raised dome. Coming from Spain though, so won't have them for a week or two.
XJR1300 rods and XJR1200 pistons (77mm)

The GS500E liners were modified as shown in the attached image.


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different part numbers:
1TX-11631-00-A0 for FJ1200
4PU-11631-00-A0 for XJR1200

but i dont know what the differences are, because the XJR pistons can be used in the FJ.
Definitely interested in knowing more, like which sleeves and rods were used... Parts numbers?
It's all there in the post you quoted.
The cheapest I found the rods were for 113 a piece. 5EA-11650 are the rods.
The liners he used were GS500E, machined to fit the XS jugs. There are many others you can use, since they are getting machined anyway. All depends on which pistons you are going with. Keep in mind, It's not cheap at all to have sleeves and pistons modified at a machine shop.