I've got a problem with my 425 and figured I would check here before I start randomly replacing parts.
The quad has always run great for the last 5 years I have owned it but has recently developed an issue that has me scratching my head. It started last year on a hunting trip. Ran fine all day and then wouldn't start. Let it sit for a while, fired up and ran great the rest of the trip. Didn't think much about it until my wife was riding it a few weeks ago. Was going up a rather long hill (several miles climbing at altitude) and it would randomly die with the classic fuel starvation symptoms. After letting it sit for a few minutes it would run fine for another 5-10 minutes and then die. When it runs it pulls hard so I doubt it is a compression issue, or for that matter a dirty carb issue. I did replace a leaky petcock (general maintenance) after the hunting trip but never thought that was related to the issue.
First thing I am planning on installing is a new fuel filter and spark plug as there is no telling how old those are, but this sounds to me like it might be a fuel pump issue.
Wanted to check here so see if someone else has had these problems and what the fix was before I start buying parts.