big bore kits

i have and raptor 350 and i want to know if thare is an big bore kit i was also looking around to see if thare is any suspention mods for my raptor

Google search on the web, they are around.

Here is an example:

POWROLL PRODUCTS FOR THE YAMAHA RAPTOR 350

Jet kit: Poly Performance Inc.*::*Engine Performance*::*Yamaha*::*Dynojet Jet Kit: Yamaha Raptor 350, Fox Racing Shox, Elka Suspension, Arctic Cat, Bombardier, CAN-AM, Honda, Kawasaki, Polaris, Suzuki, Yamaha, KTM, Beard, Twisted Stitch, FMF, OMF Performance,

Here is a thread about the suspension on a raptor 350: raptor 350 shocks

There are over sized pistons, but I don't know if there are any big-bore cylinder kits. I do know that there is a hotrods stroker kit from wiseco. That along with a 1 or 2mm larger piston might get you close to 400cc. There are suspension products available for most any ATV, including your Raptor.

If i get the big bore kit would i need to ad an oil cooler for that

I don't know that you would have too, but I think that it is a good idea to put an oil cooler on any air cooled machine.