hi I washed my ZForce 800 with a 1700psi pressure washer, my dealer is saying you cant use a pressure washer cause it will cause electrical problems, also awhile back my moto wouldn't start, took to dealer they said I over filled gas tank "really"   IS HE BLOWING SMOKE?

I pressure wash mine after every ride with a DeWalt pressure washer rated at 3800 psi and haven't had any issues, but I'd be willing to bet that you're receiving the textbook recommendations.  Technically a pressure washer could give anything problems if you blasted it hard enough.  Just don't directly spray your connections and stay cautious when when your washing underneath the plastics and I'd think you'll be fine.

As far as the over-filling of the gas tank topic...I can't speak to that.

If you over filled the petrol tank, wouldn't it just run out the breather/overflow hose.

Over filling can sometimes cause issues with emission systems. Some take the vapors from the fuel and route them to a canister to be burned later. If raw fuel gets in there it clogs up the works. I have had system warning lights come on but have never  had a failure to start over this. Use dielectric grease on every conector you come across. Cfmoto doesn't use the best conectors and the grease is cheap insurance against water and corrosion.

Don't remember who told me but I was told to keep it under 3000 PSI. Anything past that can start damaging stuff. I've got a 2800 PSI pressure washer I use, I believe the nozzle I use on comes out at 2400 and it works great.

I know when I was green and new to this I damaged the radiator my on 05 Honda Rincon. As far as the gas issue I've had that red light on my dash coming on from time to time. I started another thread about it in the Z8 section to see if I can get any feed back.

[2015 Z Force 800 53/Trail EPS]

I use a 3000psi machine on everything. No issues but I do stay a little back from seals, electrical connections, graphics and those darn reflector tapes.

I use a garden hose and my reflective stickers blew apart...   

I would be Leary of the decals peeling.

I always use a pressure washer, only problem I've had was blowing my reflectors off as well.