Hey everyone! First off, I'd like to apologize up front for my low-knowledge of quads. That being said, I have a few questions:

1. I have a 2003 400 ex that needs to be "spruced up". I've seen these big bore kits on places like ebay that has the cylinder, piston, clip and gaskets; basically everything you'd need. Are they any good? I was thinking like a 426 or 440 11.1:1...

2. If I were to purchase one of these kits, could I still run on regular pump gas at 11.1:1?

3. Would one of these kits work alright on my stock ride? The only aftermarket item I have is a K&N air filter, so I worry that a big bore kit won't work right without a pipe, cam, etc.

Any and all comments and suggestions are welcome and appreciated. Thanks!

 

research the 440 kit before you go that route. If you want reliability then a 416 or 426 is a better option. At a minimum I would put add a slip on exhaust with the BBK. You are going to be removing the cam anyway, so if you can come up with the scratch probably not a bad idea to put in something hotter while you are at it as well.

You could do it with no other mods, but you won't be getting the most out of it.

At 11:1 you can run premium pump gas.

 

Thanks for the info. Reliability is definately my preference as I do more trail riding than racing around.
Is there a good place to get a 416 BBK? As for getting the most power out it, I'd be happy enough with my stock pipe as I ride through town with it and noise is a concern
So, 11.1:1 would be the highest compression I would even think about for using pump gas with, right?
Thanks again for any and all insight!