going oversize

I might, maybe, possibly, finally, have found some reasonable priced oversized pistons for my poor scored 305. Are rings the only other thing I need to worry about when going oversize? Pins and clips and everything else stay the same? I don't see any evidence that those are different but don't want any surprises either.

How many horsepower would it add, lol? 

Are these OEM or aftermarket ?
Aftermarket pistons should come with rings, pins and clips as a kit .
OEM are usually available as separate components.
Depending on the oversize the pins may be slightly longer but the same diameter.
Clips should  be the same if OEM but sometimes aftermarket are a heavier gauge to match a wider piston groove as is the case with Wiseco pistons etc.
Care must be taken to have the correct size clip to match the groove.
 

The pistons would be OEM 1.0 over (if they actually still have them). Aftermarkets were never made, unfortunately. I don't see any different pins or clips/snap rings for different pistons so I should be OK, but wanted to make 100% sure. Someone could double-check me...

www.partzilla.com/catalog/kawasaki/motor...-b1/cylinder-pistons

 

If they are OEM oversize then pins and clips will be the same as fitted.

That's one bit of good news in an otherwise grim scene. I contacted IMD Pistons but they don't make any pistons for it. All my hopes are riding on one place that says they have em but won't wake up till it's tomorrow there.

wrote:

How many horsepower would it add, lol? 

 

At least threeve.

wrote:

wrote:

How many horsepower would it add, lol? 

 

At least threeve.

 

I started to do the math... lets see 30 hp now, new bore would be 3.14(31mm2)(52.4 mm)...etc

But I'm not sure its a linear relationship anyway and I lost interest. Negligible, I'm sure.

Plus bore x stroke x 2 comes out to more than 306cc, its more like 316, so I don't know what I'm doing.

No, you got it right: that comes out to 316.4cc. (I used 3.14159 for pi)

Another thing to consider: if the piston height is the same as stock, the slightly larger bore will give you a slightly lower compression ratio (I think) which might negate the HP gained through the additional displacement.

wrote:

No, you got it right: that comes out to 316.4cc. (I used 3.14159 for pi)

Another thing to consider: if the piston height is the same as stock, the slightly larger bore will give you a slightly lower compression ratio (I think) which might negate the HP gained through the additional displacement.


 

 I was thinking that was the stock bore, but yeah I used the radius for the oversized. So my 305 (which is a 306) gains 10 cc.
Well hell, I might as well finish now, That would be an additional 0.980392157 horsepower, I think. Look out!

I don't know why the piston would be higher but I don't know much. Most likely they won't have em anyway and the point will be moot.

wrote:

No, you got it right: that comes out to 316.4cc. (I used 3.14159 for pi)

Another thing to consider: if the piston height is the same as stock, the slightly larger bore will give you a slightly lower compression ratio (I think) which might negate the HP gained through the additional displacement.

If the piston height is the same then you are pushing a bigger "swept volume" into the same size "combustion chamber" so the compression ratio will increase 

Stock OEM oversize pistons will retain the original compression ratio.

wrote:

Stock OEM oversize pistons will retain the original compression ratio.

Are they "pocketed" or slightly shorter to achieve this?