Technical Q&A: Bad Hand Warmers, High-End Bog, Voltage Spikes
February 26, 2009
Filed under How To
Cool Hand Joe
Q: I have a problem with the handwarmers on my 1999 Ski-Doo MX Z 600. I have tested the ohms, voltage and voltage regulator and they seem OK, but the grips don’t get very warm. I sent the stator to a company in Canada; they said it tested OK. Someone said the magnets could be weak on my flywheel: Could this be true? The headlight works OK but dims down more than other snowmobiles at idle. I replaced the grips a couple of times and now have a set of Hot Grips on there, but they still don’t get warm unless the engine is running around 7000 rpm. They still are not hot like my wife’s Ski-Doo Formula Deluxe 583.
A: Damaged magnets in the flywheel are highly unlikely. Usually the only way magnets can be damaged is from a hard impact. Flywheel magnets will not wear out or lose their strength. You checked the voltage regulator; however, confirm that it has an output of 12 to 14 volts at 3,000 rpm, Joe. If that checks OK, the problem is probably caused by a power draw on the electrical system. Do you have electrical accessories on the sled like extra lights or a heated face shield? Your MX Z’s stator is capable of putting out about 290 watts. Some accessories are OK, but they tap into the limited supply of electrical energy and could cause the performance of other parts to suffer. Some aftermarket accessories require an additional ground wire to be hooked to the sled’s chassis, unlike stock accessories that are grounded through the sled’s electrical system. With a physical chassis ground at the point of the accessory, a sled might have problems like you’ve described. So, reinstall the stock warmers, and then check them for heat by disconnecting other electrical devices and allowing the sled to idle for a few minutes. If the sled doesn’t have extra electrical accessories, unhook the headlight to allow more power to the hand warmers. This exercise will confirm that the stock hand warmers and switches are working correctly. Another way to check the hand warmers is to hook up 12 volts DC directly to the hand warmers.
Use a small motorcycle battery and run power from it to the warmers’ wires; they should heat up in less than one minute. If the warmers do not heat up, inspect the wiring to the elements for shorts to ground, such as worn insulation on a wire. If wire insulation is damaged and the bare wire touches a metal surface, that will cause a short circuit where most of the current goes directly to ground instead of to the lights and accessories. Short circuits can also be present in other parts of the wiring system. For example, a problem area might be the wires that run under the gas tank and seat to the taillight. You can diagnose this section of wire by disconnecting the taillight. If you cannot find a wire with worn insulation, the hand warmer switch might be shot and not letting enough or any power to the hand warmers.
Q: I have a 1998 Polaris 700 XCR that is awesome, but last year on my final trip to the U.P. my headlights began to flicker to very low wattage and dim out. When this happened my coolant temp gauge went to full cold, then suddenly everything went back to normal. Now, the headlights don’t work. Any suggestions?
White Lake, Michigan
A: Flickering lights followed by loss of electrical power is a common problem on Polaris sleds from this era, usually caused by a failed voltage regulator. Voltage regulators are designed to prevent voltage spikes to power-consuming devices like light bulbs or warmers, but if it fails, a spike can damage those parts. The regulator is a slim box that’s about a half-inch thick and 2 inches by 2 inches; it’s bolted above the right foot well on most Polaris sleds. A yellow wire comes out of the regulator that should supply about 12 volts DC at idle. To check it, start the sled and attach an electrical multitester’s red lead to the regulator’s yellow wire, ground the tester’s black wire and then gradually increase engine speed up to 3,000 rpm. Voltage should not exceed 14 volts, but with a blown regulator, it might show 14 volts at idle. If that’s the case, the regulator needs to be replaced. Chances are the lightbulbs and warmers are blown due to a voltage spike, so check those parts after the new regulator is installed. If the voltage regulator checks out OK, you might have a wire with damaged insulation and the bare wire is exposed, allowing it to ground to the chassis or other wires. Check for melted wires near the exhaust pipe and worn taillight wires under the seat.
Q: I have a question about the Polaris Liberty 600 engine; specifically, the 2006 600 carbureted version in a RMK. I just had the engine rebuilt but it bogs out when I open up the throttle. I don’t know if it’s because the [peak] rpm is too low, my timing or the carbs or jets or whatever. It’s fine [up to] 70 mph but when I open the throttle all the way it just bogs out dramatically.
A: There are three potential causes for the high-end bog. The first is clutching. Clutch springs lose their tension after time and use. The secondary spring is probably the culprit. When clutch springs get soft, the clutches shift out faster than they should, which places too much load on the engine and prevents the engine from achieving its peak operating rpm; think of it like a car transmission that shifts to high gear too quickly for the speed the vehicle is traveling. Typical clutch spring life is two to three years, or about 2,000 miles. The life expectancy varies with riding conditions and how frequently the clutches are shifted. For example, a sled that’s run through tight, twisty trails where an aggressive driver is on and off the throttle will wear out clutch springs faster than steady running with gradual speed changes. We suggest replacing the primary clutch spring, too. While inspecting the primary clutch, make sure the weight rollers are in good condition without flat spots. The second potential cause is carburetion. Top-end bogs can come from rich and lean conditions. Make a wide-open run, then look at the spark plugs to see if they are black from a rich condition or white from a lean condition. A rich condition will cause a gurgle from the engine getting too much fuel. This can be corrected with a smaller main jet. A lean condition is usually caused from a failure inside the carburetor such as components loosening or corrosion of components causing a melted piston. A thorough cleaning and inspection of the carburetor should reveal the problem. The third but least likely of the culprits could be a bad capacitor discharge ignition (CDI) box. This isn’t very common, however a bad CDI might not allow the engine to run at high rpm. CDI boxes are expensive and most dealers will not take them back if you discover the CDI isn’t the problem. If you have a buddy, relative or neighbor with the same engine, swap boxes to see if it’s the source of the problem. This will only take a few minutes and it’s an inexpensive way to diagnose.