Tuesday Tip: In the Heat of Battle

Don¿t Let Your Hot Start Mechanism Bring You Down

Intro» Ryan Cooley // Photos» Garth Milan

With Team Rockstar Energy/Suzuki/Bill’s Pipes’ Mike Foster

You¿re leading the moto over your fiercest rival by a few seconds, when all of a sudden you go down in a corner. Unable to keep your bike running, you¿re left with just a second or two to get it lit back up in order to maintain your lead. 45 seconds later, you¿re still kicking, and that chump you should have beaten is doing heel clickers over the finish line double. Does this scenario sound familiar? Then you, my friend, have been a victim of the detrimental effects of a faulty hot start mechanism.

It¿s unfortunate, but the hot start mechanism is often overlooked in most riders¿ maintenance programs. And what many don¿t realize is that this simple device that can get you restarted quicker in the heat of the battle can also cause popping, misfiring, and even make your steed run too hot when not functioning properly. Follow these few easy steps outlined below, however, and you¿ll not only enjoy easier starts both hot and cold, but your carburetion will enjoy much better consistency than ever before.

REQUIRED TOOLS:  Carburetor cleaner, grease/assembly lube, 12mm T-handle, 8 and 10mm open-end wrenches

FUNCTION: Four-strokes need a breath of fresh air¿make that cool air¿to restart when the motor is hot. Enter the hot start button. This ingenious little apparatus allows cool air to enter into the carb tract by opening up a passage in the carburetor itself. When the hot start cable is pulled, a plunger is pulled out of the hole, and fresh, cool air is allowed to enter, thus allowing the engine to refire with ease when hot. If the plunger does not close and seal itself properly when the hot start lever is not in use, however, that same refreshing cool air will cause a lean condition, ultimately leading to a crappy-running bike.

STEP 1 The hot start plunger is located in front of the slide on the left side of the carburetor. Typically, it will have a black rubber boot and a 14mm hex head which screws into the body of the carburetor itself. Carefully unscrew the hot start base nut (the 14mm) with your fingers and remove the cable/plunger. You may need to rotate the carb on some models to get a good reach and have more room to work with your fingers.

STEP 2 With the apparatus now out of the carb, clean off any excess dirt and/or grit with carb cleaner if necessary, inspect it for damage, and then apply a thin layer of grease/assembly lube to the plunger. The grease will not only help it slide smoothly and efficiently, but it will prevent it from seizing in the carb body and will also act as a seal to help prevent air from leaking past the plunger. Carefully screw the hotstart plunger back into the carb¿snugging it down, but NOT overtightening it (the hot start base is made of plastic and will strip easily). Ensure that the rubber boot is popped firmly back into place to prevent any possible air leakage.

STEP 3 Now it¿s time to check the end of the cable on the handlebar. Most manufactures put a little rubber boot at the end of the cable that mounts onto the hot start perch. I recommend applying a layer of thick grease around the cable where it enters the rubber boot for additional sealing properties. A hot start can actually draw air in through the cable, resulting in a lean condition. Grease the cable end and install it into the hot start lever. Check for smooth pull and operation.

Note: Some aftermarket perches require that you swap the rubber boot out with their plastic cable end, but if you do so, you¿ll still need to grease this area for proper sealing.

STEP 4 The proper amount of free play in your hot start cable is very important. If it¿s too tight (no freee play), the plunger in the carb may actually be sitting open slightly without even pulling in the hot start lever. The cable should have about 2mm of play, about the width of a nickel between the lever and the perch. Adjust the slack, using the Farrell/nut adjuster on the cable itself. Always listen for the hot start plunger to bottom out in the carb. Do this by pulling the hot start lever and gently returning it to the fully closed position. You should hear a click as the plunger bottoms out. Recheck the slack and verify that all fasteners are tight. Check the cable routing and verify that the cable is not binding up when the handlebars are turned from lock to lock. Refer to your owner¿s manual if you have any additional questions.