I have a quest xt 500 and I was wondering about these aftermarket rear seats I see at canadian tire and royal distributor. The purpose is to add storage and a second seat to the atv? Is this legal or safe if the atv isnt already a two seater? My machine has a warning to only ride with one person on it. I ask because I have younger siblings that may use this thing and I dont want it to be unsafe.

Im talking about something like this:

https://www.canadiantire.ca/en/pdp/a...-0271801p.html

 

Most states go by the number of passengers the machine was designed for. In your case you have a 1 rider limit so the add on seat is not allowed!
Just so you know, the 2up machines have a longer wheekbase to balance the extra passenger.

 

On my ATV trails (in Canada), they sometimes patrol ATV Trail heads and filter for non-legal setups - like illegal "booster seats" usage. And when loading up / unloading, they also deeply inspect trailers, their Tie Down details and even for Tow Vehicle violations. Being compliant & friendly to authorities is best for "warnings only". Smiles.

Under their rules, legal 2-UP ATVs (like my ATV) is allowed to have 2 people. They are longer wheel base machine, rear passenger weight is a head of its rear axle and their engines are larger size as well. Thus, won't "lug down - stall and roll backwards down a hill". Or, less risk of end/end roll overs due to its improper weight balance as well.

When they do catch 2 people on a single seat ATV (and 2nd person is using "booster seat") coming out of the ATV trail head, they are given a written warning. re: Never double ride on factory single seat ATV again. If they are unloading at trail head and get caught, they are told to load their ATV back on the trailer and go home. No booster seat usage is allowed rule.

When they catch the same single seat ATV owner riding double again, they get fined. No way out of it. But.... Exceptions of broken ATV left in bush and double riding 2nd ATV owner out of the deep bush trails "double riding exceptions" are taken into consideration. Always best to have a witness under these double riding with no fine exceptions.

For me with a 2-up machine, I agree with above. Factory 2-up machines with Power Steering make for a more smoother / enjoyable ride anyway....