440 piston

[patrick delao]

Does anybody have a wiseco 440 kit in there bike. If so is it a 11 to 1. I need to know if you have the part number of the piston so I can see if they gave me the right compression piston. My number is 4667MO8900 I'm use to seeing a slight dome for high compression and big dome for real high compression. Please help.

[MIKE400EX]

That's the 11:1 440 piston. 4667 is the p/n, 89.00 is the bore size in mm. The combustion chamber is not too big(relatively speaking), so it doesn't take alot of dome to make compression.:)

[patrick delao]

I just didn't want to put a 10 to 1 or something else, I got the old stock piston and stuck the wrist pin in both the stock and the 89mm and the top of the pistons are exactly the same height. I would think the wiseco would have a lower wrist pin height for the more compression. I guess the bigger bore gets you higher in the chamber for the added compression? Thanks for the help. wish me luck it goes in this weekend. :)

[MIKE400EX]

Yeah, .160" extra bore does help the compression! I've got the same piston waiting patiently to go in - some day. If you can, please weigh the stock piston,rings & pin together and post the results. I want to compare the two before I dig in. Don't forget to upgrade the cam - then you'll be REAL happy. Good Luck. :cool:

[patrick delao]

That was exactly what I was going to do I wanted to see if the 89mm was way heavyer and thats why your sopose to get a litttle more vibration oh also I have the XR cam

[MIKE400EX]

There's definetly extra material to remove weight from the piston - without sacrificing strength. FYI, the XR cam adds about .010" additional intake lift, .020" exhaust & 6 deg (above .050") intake and exhaust duration to the EX cam.

[patrick delao]

Thanks for the cam info Mike. :) I weigh the pistons anthe 440 wiseco piston weighs 68 grams and the factory 400 piston weighs 64 grams. Pretty impressive on the wiseco for being that much bigger then the stock one and only being 4 grams more.

[Chef]

looks like a gram a mm...

[badass400ex]

anyone have the weight of a je 10.5-1?