No motorcycle is perfect. Even the most well-maintained machine will inevitably have a few problems that pop up here and there. You don't need to go running to your nearest dealer or mechanic when things get squirrely, though. Here's some tips to help you sort through what might be wrong with your ol' motorbike if it's giving you a headache.

Electrical

If you're not getting power to a critical component of the bike like the starter or ignition, or are having issues with misfiring, here's a few things to look for.

First, if you recently washed your bike, keep in mind that high pressure car washes can force water into the plug wires and electrical connector plugs. Water can also seep into things in other ways if a connection is loose, or a covering or coating on a wire is worn out. The water in these connectors, or soaking into the plug wires, can change resistance values and will cause poor performance and misfiring even when everything appears to be dry.

When dual plugging engines, in most cases it's necessary to retard your timing by about 5 degrees to achieve the best results. Adding an additional spark on the opposite side of the combustion chamber will speed the burn of fuel and effectively advance your timing. Different heat ranges of spark plugs can also have an effect. Extended tip spark plugs will burn fuel quicker than standard or recessed tip plugs, because they are out in the chamber further. Timing, spark plug, heat range and jetting should be done by a good tuner for optimum results.

Lighting

If your headlights, taillights, or turn signals aren't working correctly, check all connections and wires. When installing additional lighting on a motorcycle make sure you use heat shrink tubing and inline fuses on the power leads and wherever connections are made, waterproof them as much as possible. Bad connections caused by moisture are the leading cause of lighting failure.

Dash & Speedometer

If your speedometer is acting up, make sure you're up on it's maintenance. Speedometer cable maintenance interval is 5,000 miles. The recommended lubricant is a graphite grease. The grease is applied sparingly on front wheel drive speedometer cables to prevent the grease from being thrown. The front wheel drive unit also should be checked and serviced at the same interval. If any excessive clearance and roughness is found, the drive unit should be replaced.

Carburetor

If you have an older carbureted motorcycle and the carburetor isn't delivering the right fuel-air mix, your bike isn't going to run well at all. Before tearing the carbs apart to rebuild them or re-jetting your carburetor there's a few other things to check. Make sure the fuel-air mix screw is set to where it needs to be. This is especially important on aftermarket carburetors which might need to be adjusted differently from an OEM carb.

Also make sure that your timing is set properly and if you have a mechanical advance, make sure that it’s not worn out. A worn out advance unit will allow your timing to advance too far and show up as a lean condition on a perfectly jetted carburetor.

Transmissions

Around 90% of shifting problems on Big Twins and Sportsters can be traced to the shifter mechanism and its components. Early model ratchet transmissions on Big Twins are usually much more forgiving than the later Maytag and later Sportster shift mechanism. Not only do worn-out shift mechanisms make shifting difficult, they can ruin perfectly good gears if not taken care of. When installing replacement ratchet tops on 4 speed transmissions never assume that the shift fork setting will remain the same. Always use a shift fork gauge to align the shifter forks. You should also set the “timing” on ratchet types when rebuilding. This is done by loosening the common head screw that holds the spring holding plate on and rotating the plate back and forth until you have an equal lever throw upshifting and down-shifting. If the ratchet tops “timing” is off they can shift perfectly one way and poorly the other. Avoid using Loctite on ratchet top screws and never over-tighten them. Bolts that have Loctite used on them can be very difficult to remove and many a good casting has been cracked because of over-tightening. Use oil or anti-seize on ratchet top screws and tighten to 80-110 inch pounds, and don’t worry it won’t fall off.

To properly adjust a clutch on an old Maytag top 4-speed transmission, you first screw the cable adjuster all the way in. Next, you should break loose the lock nut on your clutch adjusting screw and screw the clutch adjusting screw in or out to achieve a measurement of 1 3/16” from the transmission top cover to your clutch release arm. After this critical measurement is achieved, tighten the lock nut on the clutch adjusting screw and take up your clutch handle free play with the cable adjuster. Leave at least 1/16” free play in your lever to avoid shortening throw out bearing life.

Brakes

When a brake system or fitting is opened the fittings should be flushed and the system bled to keep air and contaminants from entering. Use Teflon tape or pipe sealant on all brake line fittings. Lubricate all internal parts of master cylinders and calipers with the same grade of brake fluid to be used in the reservoir.

Oil Tanks

Never use silicone sealant when installing oil pump gaskets. Silicone can clog oil passages in your engine causing costly damage. A good coat of aluminum based paint or a copper spray sealant can give good results on paper or Mylar gaskets.

Driveline

Sprockets are usually only good for the life of two chains, then it is best to replace both sprockets and chain all at one time. Worn out sprockets will ruin a new chain in no time.

When replacing rear sprockets, you should closely inspect your chain and transmission sprockets. If any one of these final drive components are worn, they can and will cause premature wear and failure of the new rear sprocket.

Wheels

It is advisable to service front and rear wheel bearings every spring or every 5,000 miles, whichever comes first. Keep the pressure washer away from the bearings.

Handlebar Controls

Lubricate throttle sleeve and housing with a light coating of graphite. To remove grips use a long thin pick or screwdriver. Slip it lengthwise between grip and bar or throttle sleeve as far in as possible. Spray WD 40 or contact cleaner in cavity created. With a twisting motion remove grip. If not successful first time repeat procedure. For maximum life of throttle cables, lubricate every 5,000 miles. Lubricate cable with light oil or cable lube and lubricate elbow with grease. Do not use chain lube on any cables.

Frames

When installing shorter shocks, tire fender clearance must be checked. To do this, install one shock with spring removed and compress shock. You must have at least 1” clearance from top of tire to fender to allow for the growth at higher speeds. With shocks removed, now is the best time to check swingarm bearings.

Windshields

Never clean acrylic screens with glass cleaner. The solvent action of the alcohol in the glass cleaner will destroy the acrylic. Do not allow brake fluid, alcohol or strong solvents to contact the screen. Permanent damage will result.