anyway of telling a 400ex has a 440 kit???

[sprt400ex]

i traded for a "440" ex and i raced my friends stock ex. and it was close. i have 20'' holeshots on the rear running 16 -39 sprockets.
would it be because of the sprockets and tires?? is it that close with a 440?? is there anyway to tell its got the kit?

please help me out

thanks

[airheadedduner]

What else does it have? If it is a 440 but they sufficated it with a wussy exhaust, stock carb, and such then it may not be as fast. And yes your gearing has a lot to do with it. I would drop a tooth of the countershaft if I was you.

[wilkin250r]

There are lots of factors to a big bore. If you only have the bore, but it's not high compression, running the stock cam, and stock carb, you're not going to see much difference. Also, you're jetting can severly affect you power.

Other than taking it apart and measuring the bore, there is no way to determine if it truly has a big-bore kit in it.

However, I'm not even sure it's possible to get a 440 piston that's NOT high compression. I'd do a compression test between your motor and your buddy's stock motor.


If it was done properly, a 440 should spank a stock 400, even with a 16t front sprocket.

[sprt400ex]

440 wiseco bigbore
polished and ported head
White Brothers CDI rev box
jetted
White Brothers E-series pipe
no toil filter with open airbox.
i have the stock cdi also so it has the white brothers.
it runs perfect. could it still be jetted wrong?

i was thinking that a cam would do a whole lot and bring out the motor work.

what do you think?

[nacs400ex]

I have a funny feeling that it aint a 440.

[MIKE400EX]

If it is a Wiseco 440 piston and the builder didn't correct the deck height then it only has about 9.7 to 1 compression. In other words, that mod only didn't net much of any gain. Fix the compression and you'll see a little, add a cam and you'll see a big gain, add a carb too and you'll be real happy!

[whatwasthat]

I have wiseco 11:1 "claimed). Anyway, how could i correct the low compression? Or, should i just tear down again and get a je. An if i do, should the 88.5 mm je fit the wiseco bore?

[F-16Guy]

Originally posted by whatwasthat
... how could i correct the low compression?...
I think, far and away, the best thread on this site regarding this problem (probably the best thread PERIOD) is "have you decked the cylinder". Type that into the "search" feature and read the whole thread. It will probably take you a half hour to read, but you'll learn everything you ever wanted to know about how to determine compression ratios, and how to get the correct ratio when you assemble your engine. Good reading! ;)

[sprt400ex]

guess im looking at taking the whole engine apart :( definitly dont think its a 440 either.

live and learn

[PHIL_B54]

have you decked your cylinder is now in the FAQ section, an it is one of the most helpfull threads if you are questioning the compression/bore