Saints Row 2

Difficulty 3/10
Time: 1-2 hrs
Description: There are a total of 27 races (10 car, 5 bike, 7 water, 3 helicopter, 2 airplane). To find these races on your map just scroll over so that you can see is activities. The races are marked with a checkered flag. The achievement is just completing the race. To do this you must at least achieve a bronze medal. There are two different types of races, which are against the clock or against 3 other AI drivers. If you are going against the clock then all you have to do is beat the bronze time, If you are racing 3 other AI drivers the all you have to do is come in 3rd or better, just don't come in last

It may be mentionalble that you can use your own cars and bikes for the Races depending on what kind of Race it is of course.
I found a fully tuned Vortex for the Car Races the best choice because this car has a super tight steer.
And the fully tuned Kenshin for the Motorcycle Races.
All other Races in Helis Planes and Boats are just checkpoint Races and are easy going.
I found the following Map better to track down your progress of finished Race:

EDIT: Well it seems the interactive map at MS-World is down again. I´ll check from time to time if its going to make it back. In the meantime you best write down what race you finished in what Row/Hood whatever.

Well after looking at the other solutions and looking at videos I had a little brainwave.
Press the back button and bring up the map select activities and zoom all the way out.
take a photo of the tv screen (with the map on there) with any smartphone and email it to yourself open the photo in microsoft paint and cross off all the races as you unlock them, Also save after every 2 races it will not autosave and it does like to crash halfway through a race.
The road races are a mix of time trial and AI position races and yes bronze or 3rd place is all you need to have "completed it".
Use the vehicle it gives you to do the race it's the same as the AI and stupid easy to beat with them you DO NOT need any "pimped out super fast cars".
All boat races are just time trail and easy done if you don't rush them and DON'T do them when it's raining (yes makes a big difference)
All helicopter and plane races are time trials and again not that hard if you take your time and don't rush them also using the LB/RB for rudder control helps and when you come in for the landing you just need to hit the green marker not land fully.
Just a few little bits of info:-
Beat all road races get a race car for a reward,
Beat all boat races get a special boat for a reward,
Beat all helicopter get a special helicopter for a reward,
Beat all plane and you guessed it a special plane is your reward.
Hope this helps

I just finished getting the achievement today so I am writing this guide here's what I think would help you guys out:

1) When pertaining to Car Races, as AkkonShinigami said, you can use your own vehicles so here's what I recommend. Use a suped up Five-O (Upgrade everything you can ESPECIALLY Kneecappers.) Kneecappers are the greatest thing in the world and I will happily tell you why. They will destroy the rubber on the tires of the AI cars and if done right, they will be unable to handle their car and it will be an absolute breeze. I recommend smashing into the other cars as soon as you can to insure the best results. Considering you only need to get Bronze this all becomes a matter of taking out one of the other cars.

2) Boats/Jet Skis Races, these aren't too bad… Just take your time when navigating around pillars or islands and it shouldn't be hard to get a silver or even a gold medal on these.

3) Helicopter Races, this is where things can get difficult. I don't really have a ground breaking trick on how to do this. Just try not bumping into anything and taking things slowly. You might run out of time but with enough practice these are fairly manageable. I think at most it took me at most, 3 tries to get all of them done. I am also not a good flyer when it comes to these mechanics where there's a lot of finessing due to the game being so old.

4) Plane Races, while there are only 2 of these. They will easily be the hardest races to take on. Don't worry or be afraid of them! They will require practice and if nothing else patience. I struggled to get these done but after enough failed attempts I learned the course and was able to do the first race fairly easily. Just need to take it slow towards the end because you will have to be getting close to the ground so the slower, the less impact/damage you will do to the plane. Towards the end you will have to avoid a street sign. It's obnoxious but just do your best and you will be able to do this one. Now for the one that was absolutely obnoxious, there is the final plane race which is in the Airport District and what is expected of you is quite difficult. You must maneuver under a freeway and then almost immediately go above another one. It's a very tight squeeze and it is nothing short of a struggle. I got it on my 6th try (which was probably 99% luck, 1% skill) but once I got past that one part, the rest was a BREEZE. So just take it slow and hope for the best. I can't say you will get as lucky as I did on my 6th try but I promise you it isn't as bad as you may think it is. If you find yourself getting overly frustrated and unable to focus, just take a break. Go watch your favorite tv show or listen to music. Once you lose your cool, this race will not be possible.

If you found any of this helpful then a like would be appreciated and if you found it useless please comment what I could possibly elaborate on!