How do i remove the seat on a honda bushlander ctx 200 ag bike

I would use circlip pliers.

guessing this a small motor as in mower or such
most likely a failed magneto or coil

bad brain box/cdi, did it cut out after it got hot?

AG bikes are not designed for performance. If the bike is working as intended by Yamaha, then it is for farm use only. If the suspension is leaking oil or become 'springy' then new fork seals and a back shock replacement or rebuild may be needed. If you want the engine to go faster then you need to seriously look at buying another bike because the AG200 is not designed to go 'fast'. If you are after a trial bike you might want to look at Honda CRF250L, XR250/400, Yamaha XT or TTR250, TT350, Kawaski KLX range. Enduro bikes: Yamaha WRF250/450, Honda CRF250X/450X, Suzuki DRZ400, RMX250, Kawasaki KDX200 (2 strokes are easier and cheaper to rebuild) so my choice would be RMX, KDX, DT200, Husky WR250/300, KTM300 - these are cheap 2nd hand too! Don't buy a bike that is way out of your ability range. Ride on!

Rickimatt,
Try the Motor Bookstore.com
When you get there type in XR200.
Raven - Maniack