Each month we receive a flood of technical questions from our readers. We've taken away Mike Newsom's Xbox and placed him in charge of answering these questions. Mikey is one of the most talented mechanics we know, but it's his off-the-wall answers that weird us out. If you dare to bear his response, send your questions to atvrider@sorc.com. We promise not to let Mikey use your name and embarrass you in front of your buddies.
Ask: I recently purchased a used Honda TRX250R. The 250R is rebuilt and all tricked out. The guy who I bought it from claimed I should use a 32:1 oil/gas mix, but the bike itself says to use 20:1 oil/gas mix. Do the motor upgrades of this bike make a difference in oil ratios?
Mikey: My first recommendation would be to deliver that beast to the ATV Rider Compound for some proper testing before you go grab a handful of old-school power and get yourself hurt. Being that the 250R is my all-time favorite ATV, I would gladly burn through a few tanks of fuel and let you know how she runs. The factory tank does have 20:1 stamped into the plastic, but if the previous owner has it set up to run a specific brand of oil at 32:1, that should be fine. I prefer to stick with one type of oil and refrain from jumping between brands.
Ask: If I leave my 1994 Yamaha Timberwolf 250 2x4's gas turned to the on position when not running, gas runs out of the drain tube connected to the bottom of the carburetor! Any idea what is causing this? Obviously, it makes the bike hard to start, and even if I turn the gas to the off position, that just means the carburetor gets drained dry. It does not appear to leak while running. HELP! I'm guessing it is some kind of bowl or float issue. Should I just replace the carburetor?
Mikey: Hopefully you have put out any burning cigarettes and managed to stay away from open flames during the time this magazine was being printed. If not, you can proceed with the marshmallow roast, but if you managed to make it this far, your troubles aren't as bad as they seem. You definitely have a float that's sticking, but this problem doesn't require a new carburetor. You can start by removing the bowl and cleaning the float to remove any debris that could be causing the float to stick. If the problem persists, a rebuild should be available through your local dealer.
Ask: Hey, I just bought a 2004 Yamaha YFZ450 and it has a complete Yoshimura exhaust. I'm not sure what it's currently jetted at, but the airbox lid is off and it has an aftermarket air filter, not sure what brand. The problem is my exhaust glows red after running for about five minutes. Is this normal? I don't want to ride it and damage anything.
Mikey: Unless you plan to lead Santa's reindeer out on a foggy Christmas eve, I would do an inspection to find out what jets are being used. It is normal for the YFZ's exhaust to get extremely hot and sometimes glow, but if it's running too lean, the heat could be excessive. I don't know what mods have been made to your machine or your elevation, but I would say that a 48 pilot jet and a 172 or 175 main should be pretty close.
Ask: Hello ATV Rider. We have a 2003 Polaris Ranger that continues to overheat. For some reason, the fan isn't coming on when it's supposed to or at all. We've taken it to a shop several times, and they charged us $100 or more and it still isn't working properly. We hooked up a hot wire directly to the fan and that worked. Any ideas as to what's going on here?
Mikey: After I paid the first repair bill and the fan continued to malfunction, I would've immediately returned the machine to the dealership. If they continue trying to squeeze cash out of you, I'd contact the area's Polaris rep and continue up the ladder until the problem is resolved. If the fan works when connected to direct power and doesn't come on when the machine is hot, there's an electrical problem. It could be something simple like a bad thermal sensor on the radiator or a bad electrical connection.
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