First off this will be my first tech write-up, so be gentle. I decided to drain, flush, and replace my coolant in my 07 Predator today, and thought I would document the steps for my fellow riders.
1) First off, I got my coolant, distilled water, and white vinegar together. After reading tons of positive reviews, I decided to go with Engine Ice. I also read that the system should be 100% purged of any old coolant prior to adding Engine Ice.
2) With the engine cool, I uncapped the radiaitor cap and found the drain screw (it is the bottom bolt on the water pump, I included a pic of the exact one to unscrew) It is a 8mm bolt, and was a little snug, but be careful not to be to hard, these bolts are easily breakable. As soon as I got it loosened, the green fluid started pouring out quickly. Since I have nerf bars, and a skid plate placed a little funnel to let the fluid flow nicely into my drain pan.
3) This step may not always be needed, but since it was probably never completed on my Pred before I decided to pull off the lower radiator hose and clean it up/install for any issue. I also cleaned the overflow lid, cap, filter and radiator cap.
4) I replaced the 8mm bolt into the water pump. I took the water, and put it into the vinegar with a 50/50 mix. I proceed to fill the radiator with my mix until it was full, and started up the bike for approx 15 minutes to warm up.
5) After letting the Pred cool down for 30 minutes or so, I repeated the everything in step 2. I actually decided to repeat the whole process again to insure that all of the old coolant was 100% out. I also tipped the quad over towards the water pump drain hole and probably got another 2-4 oz out. At this point, I also unscrewed the overflow bottle, and dumped out any fluid that made its way in during the 2 flushes.
6) I tightened up the water pump drain bolt, and started to fill the radiator with Engine Ice. As my friend was filling, I squeezed the upper and lower radiator hoses to help "burp" the system and purge out as much as air as possible.
7) Last step, I swear!! I filled it until it started to overflow, replaced the cap and ran the Pred for 10 minutes. I it cool a little, and filled the radiator again until it was topped off again. I also filled the overflow bottle to the line on the back. I used most of the bottle of Engine Ice, with just a little left over. I plan on running it for 30-45 minutes the next day or so, and check the fluid level again, fill as needed.
Hope everyone got something good from this, if you have any questions/comments please feel free to ask. Also, for a quick tip if your chain has any light rust on it, take it off and place it in some clean oil for a day or so. It will really lube it up well!!