should i crack the bottom end

[ladyluckracing]

I need some advice from all of you with engine building experience
i have a 400 ex and i am doing the following mods,
J E piston 426 12.5 comp
webb stage 2 cam
pro curcuit headerpipe and muff. [ because it was there ]
curtis sparks rev box
450r carb
massive head work intake up one size exhaust up two
full port and polish, and to get rid of the nasty hump on the exhaust.
head stud kit


My question is, should i open up the bottom end and have the
crankshaft and flywheel counterbalances machined down to get the rpm's to come up quicker?

[Buffalo400]

Je 12,5:1... A HD connecting rod will be a must, too much stress for a stock rod... IT's why a lot of people used a 11:1 piston. So, when the cases will be splitted, cranks bearings remplacement can be a good idea.

[atvracer980]

I found that no matter what aftermarket rod you run w/ a high compression piston( 12:1 or greater) your gonna put excessive wear on the rod bearings- I had a Carrillo rod on my 440, it lasted a season of races and the following year I was in the same boat as the year before- a $600.00 bill for a rod replacement, since it was my 2nd time spending $$$ on the bottom end, I was advised to drop the compression of my piston and use a Nix rod- Ive been running 2 years on the same rod w/o any issues- I tear my motor down twice through the season and check everything. I would suggest maybe lightening the flywheel, if you want your crank balanced- the labor of disassembly and re-assembly of the lower end could be expensive unless your able to do it yourself- I myself choose not to because of too many shims and vital parts that have to put exactly where they come from to work properly.