Yamaha big wolverine
 

So I've been beating my head on this quad for about a year having it only work about half the time. The suspect in question is a 2000 wolverine 350. Long story short the molded case and had a few uh-oh's inside but only on the starter side. The bike will still run fine but will never again have electric start.(kind of a big deal for me plus I've had this on my mind since I got it) now I'm wondering if I could up the motor to get more out of it. I've read the big bear 400 bolts right up with a few exceptions and also that the gearing would go great with 2nd and 3rd from the wolvy along with the secondary reduction(not sure what that is if I'm being honest) I'm still fairly new to transmissions so I'm looking for advice on what to do here. I want it to be a beast on the trails and in the mud but most importantly I want it to be reliable! Any help is greatly appreciated

For what it is gonna cost for all the parts and labor you will still have a big ? on the reliability! Might as well bite the bullit and get a left over 2017 or 2018 newer model machine. No matter what you do to that old girl....she aint gonna tear up the trails like a newer machine would! If you really plan on tearin up the trails...dont do it on public riding trails please!!

I never ride on public pubd anyway. The bike I'm talking about has been on the same family farm for 15 years and I'd like to keep it there and working. I also do not like the big body of the 700s out there. The 350 is nice and somewhat compact with plenty of power to weight ratio plus it's not too much to teach kids to ride on. It is also a centmential build since it's the first motor I've ever rebuilt and the while family bike thing.