WEISCO or JE

[Guest]

Which is the better piston. Planning on a bore job this winter. Want 75mm with 10.25cr. Any advice? 1980 GS1100. 16valve

[almarconi]

Ask rapidray.

[BassCliff]

Hi,

Ask rapidray.

...or chef1366, or Kris V.


Thank you for your indulgence,

BassCliff

[laverda1200]

forged vs cast

Which is the better piston. Planning on a bore job this winter. Want 75mm with 10.25cr. Any advice? 1980 GS1100. 16valve

stock factory pistons are made by a casting process. When you start the engine, the expansion rate of the cast piston is very similar to the expansion rate of the cylinder liner, so they warm up together without much by way of problems.

Although stock pistons are made by casting, aftermarket pistons are made by a forging process. What you actualy need to know is that a forged piston will expand faster than a cast piston at initial startup. You also need to know that the forged piston will expand more quickly on initial warm up of the engine than the cylinder liner it is running in will, so don't hammer hard on a cold motor. You need to follow the piston manufacturer/supplier clearance specs to the letter, effectively the clearance used for a forged piston is typically around .0005" larger than for a cast piston.

both J & E and Wiseco supply forged pistons. I have used pistons from both Wiseco and from J & E in a number of air cooled motorcycle engine builds, with great results from each.

I have installed a number of custom made J & E pistons in air cooled three cylinder Laverda engines, and once I took the different characteristics of forged pistons into account, have had great results even from big displacement increases, going from stock cast 75 mm pistons to 80 mm+ forged pistons in oversized liners.

to decide between J & E and Wiseco, I would likely go with whichever was cheaper, frankly, the quality is likely about the same.

cast vs forged pistons has some of the same issues as switching from stock valves to stainless steel valves, typically the stainless steel valves have to be run in somewhat "looser" guides with greater initial cold clearance to prevent rapidly expanding stainless steel valve stems seizing in the slower to expand stock valve guides on initial start up.

also, make sure you get your matched ring sets from whichever piston supplier you choose, and follow the end gap and installation instructions to the letter for best results. Finally, you need to find a decent machine shop to do the overbore for you, lots of ways to **** that up badly, unfortunately. I would be way more concerned about choosing a great machinist, actually, rather than whether I went with Wiseco or J & E. The key to success with the forged pistons from either supplier in your engine build is all in the hands of the machinist doing your cylinder boring work, don't cheap out on the machinist.

Paul

[Big Jay]

Both are excellent. The JEs are forged from 2618 material, Wisecos from 4032. The 4032 a high silicone material that expands less therefore can be run tighter.

We are a factory warehouse distributor for every major brand of aftermarket pistons made for the GS. http://gszone.biz/pistons.html

[OLDENUFF]

Thanks for the input. I was planning on sending it to APE for machining.

[Flatline_Racing]

Another option would be CP pistons

[laverda1200]

I don't have any personal expereince with CP - Carillo pistons, but i have built lots of motorcycle motors using Carillo rods. The rods are extremely high quality, and almost too pretty to hide inside a motor.... I would expect there pistons to be high quality as well.

Paul

[rapidray]

I used to work at CP & am a WD dealer for them. You can get the Wisecos & JEs for less but the CPs are the best you can buy! Ray.

[Guy]

I bored out my last GS1000 and fitted a Wiseco kit. I'd fit another if I could afford it.

[Big Jay]

Thanks for the input. I was planning on sending it to APE for machining.

If you get the pistons from us at the same time, you save on the machining.