bore over on a already modded 400ex

[chucky797]

ok i just came across the decisoion. i am woundering what you guys think about me boring over my 400 to a 440 with a stock compression. currently i have a 2001 trx400ex with a turbo on it. it is running 14lbs of boost. the only concern i would have is the head gasket. do they make a copper one or a metal one. my friends and i say i should put the stock pistion back in. currently i have a 8.5 to 1. thanks for the help

charlie

[cals400ex]

i would run a forged, low compression piston. all of the headgaskets are metal, well all of the decent ones are anyways. why go to a 440? i would do a 406 or something like that if it was me.

[chucky797]

i know that i want low compression to a point. i would want a little higher to get my turbo to spool up quicker. do u know any places that have a forged pistion in a stock compression rate. also what is the stock compression? 10 to 1? i would also like to go to a 440 just so i could have the extra power. i have a stage 2 hot cam and all of the goodies in it. just want that turbo to kick in a little quicker.

thanks
charlie

[1fst400]

poast up some pics!!!!!

[Pojo450r]

what type of rideing are u doing on this bike

[chucky797]

i will post some pics in a few days. i have it all taken apart to clean and rejet for the winter. i am going to ride motocross, trails, and other stuff just for fun. maybe a little drag racing in there

[400flava]

thats sick! alot of boost for a small engine what kind of turbo u running on it? and get pics i want to see this thing...

[Dixie440ex]

I have a 440 in my bike Cometic sells a steel gasket set for the 440 it has a steel base and head gasket set. If i was you i would also put an over size stud kit in ur bike. Idk about compression ranges all i have ever heard of is 11-1 12-1 the 11-1 is more reliable.

Put some pics up of this turbo

[cals400ex]

stock compression is 9.1:1. i would still go with a smaller bore if it was me. those 440's dont' rev as high.

[K_Fulk]

I think wiseco makes some 10:1 pistons.

[chucky797]

here is where i posted them

http://www.exriders.com/vbb/showthread.php?s=&threadid=277261

here is my new question. i have looked on wiseco and they have a 10 to 1 compression. would that be good if i went to a 426 or a 440 bore. it seems like i should run a like 11 or something. what do u guys think?