Topic: Piston identification help!

[RottenRalph]

Hi everyone, I'm hoping to get a positive ID on some pistons I bought a few years ago and possibly get some other questions answered!

The dimensions:
- 15mm wrist pin
- 64.89mm
- pin-to-shoulder matches all my other 750 pistons
- 31/34mm valve relief cut-outs 180 degrees from each other
- 6.6mm dome height from shoulder
- 3mm wide shoulder
- small 'w' and '4016' stamps found on underside

Now I've contacted Wiseco who seemed to think just based off the numbers that they are their '4016 M06500' 65mm 836 kit pistons but they look nothing like them in my opinion... they look far more like their big bore kz650 pistons which I know share the same diameter wrist pin and shoulder height as our 750s, does anyone have any experience with this?

I know others have used kz650 pistons as 811cc kits in the past but they have had to machine larger relief pockets due to the offset valve angle in our 750s.

Final question - Can I run these unmodified? I have a K8 engine which I've bored out for 62mm CI pistons but the ones he sent were crap and I can't use them and I've received no reply to my messages. Rather than buy more possibly crap pistons I would like to bump up to 65mm using these nice forged ones but I don't want to pay a machine shop to bore my cylinders out for some pistons if they need too much modification themselves.

392 head, KH 'D' grind cam and stock rods.

[Tim2005]

Check out the 65mm Wiseco here, seems the same crown and has 4016 on it, but skirt is shortened at the sides http://www.satanicmechanic.org/bigbore.shtml

[scottly]

Did Wiseco state what the compression ratio of the 4016 pistons is, or if they were for the larger F2/F3 combustion chambers?

[RottenRalph]

Check out the 65mm Wiseco here, seems the same crown and has 4016 on it, but skirt is shortened at the sides http://www.satanicmechanic.org/bigbore.shtml

This is what I mean, the relief cuts on the Wiseco pistons are far wider than what I find on these, just looks like a completely different piston!

Did Wiseco state what the compression ratio of the 4016 pistons is, or if they were for the larger F2/F3 combustion chambers?

Its the 10.25:1 CR piston, I believe they cut the reliefs wide enough that you can use them in any of the cylinders, as cyls 1+2 are mirrored to 3+4, JE pistons cut their reliefs at an angle so that you can only use 2 pistons on one side and the other for the other side as the valves are angled in our SOHCs.

[RottenRalph]

These are Wiseco's 4037 64mm Kawa kz650 pistons and they look more or less spot on just 1mm smaller, which is why I suspect mine are actually kz pistons but it's odd that they are absolute stamped with the 4016 (836 kit for a cb750)

https://www.wiseco.com/shop/powersports/pistons-powersports/piston-kits/kawasaki-kz650b-f-wiseco-piston-kit/?srsltid=AfmBOork9ClwUX_IXHThpL58FuZ0EnkB70Ldvp9YLuz8_g1ZyzivdOZ4

[Don R]

 Products evolve over time and these have been made for a long time.