Wiseco Piston Kit

[397ccEX]

Hey who has experience with a Wiseco piston kit?
Im lookin at them in Rocky Mtn and there is two diff kinds to buy one says "STD" under bore and the other say ".040" under bore
Is the .040 for 440ex's and STD for stock 400exs?
Do you get alot of power

[Destructo]

it should actually be "over" STD would be a standard bore, .040" mean fourty thousands of an inch over, I don't think thats even 416ccs, I think to get 416 you have to go .080" over? But I don't really know, but thats what the numbers mean, .040" over standard bore size.

[397ccEX]

So std is what i need for an stock bike
its not bored or anything
would i get mor power from it?

[Destructo]

If you up the compression ratio your going to get more power, mostly bottom end from the extra compression, usually upping the compression and then running a bigger cam will give good gains. however I have no experience with this on a quad, somebody else will have to answer the power question.

But, yes STD, would be what you need for a stock motor that has never been bored.

And while were on the subject what kind of compression can you run with a stock or close to stock cam and running on 93 octane? 11.5:1 or so would be my guess? My XR200R has 11:1 stock, and it seems to run on 93 just fine.

[torqen2k1]

I think the .040 would be a 406 correct me if im wrong. I just had Weisco 11:1 put in my 426 and its runnin go "nock on wood."

[Destructo]

I thought about doing a 11:1 piston or so in my 400ex and then putting a cam in it, but its got plenty of power that way it is and I don't want to put a pipe on it because I like it quiet.

[mojoe2878]

you will gain some power out of the higher compression piston, i dont suggest going over a 11:1 ratio with the stock rod. have your cylinder checked and see if it needs a bore job or just a hone job to clean it up before you buy a piston so you make sure you get the right size. with a 11:1 piston and a cam like a hot cam stage 1 you should see a nice power gain, you will see more of a power gain if you go ahead and bore the cylinder out to a 416. a 416 is a good bore for the stock sleeve.