The most FAQ's about the XS650

So you have your XS650 and now it's time to get it to Run/Stop/Charge/Stop leaking/Quit popping/Start easier etc. Remember, on a bike that's at least 24 years old now, somebody may have changed something in the past, always expect to find out that parts have been swapped around. These tips are gleaned from personal experience, readers contributions and the XS650 List Server.

Fine print and disclaimer: This information is provided "as is" and is not in any way endorsed or guaranteed by  650 Central. Some of the tips are common sense, some are real technical wizardry and some are old wives tales. When using them, you assume all risks involved, period. No exceptions.

First some pontification from your sponsor:
Buy a repair manual
if you don't already have one. It's full of info for the novice and seasoned wrench alike. Buy one from us (preferred) or any good bookseller, just get one, you'll be glad you did. Another "must have" is an OHM meter. Beg, buy or borrow one.

Fuel System

  1. Clean the carbs. Really clean them. Take them off and completely apart (butterfly and seal removal recommended), soak them in one of those 1 gallon Carb cleaner kits from the local NAPA or Pep Boys. Clean every jet and passage. Low speed jets/circuit have a bad habit of varnishing up and then the motor won't get fuel to start or at low RPM. Be sure to submerge brass floats, too, if they contain fluid when you pull them out of the "juice" you will have found a leaker and saved yourself a lot of grief down the road. Floats can be soldered.
  2. Inspect carb diaphragms for cracks and holes. People have repaired minor damage with rubber cement and a variety of other glues and patches. You can try it too if you want to, otherwise replace them if they are damaged.
  3. Set the floats, clean the needle and seat. Don't replace needle and seat unless you know they are "leakers", you'll find out sooner or later if they are, save your money for now.
  4. Don't fool with the jetting on a bike that's not running. You can do that later.
  5. Do clean or replace the air filters.
  6. If the fuel petcocks won't turn, don't force them, take them apart and clean/reassemble or rebuild them. Soak them in penetrating oil or other light oil before taking them apart if they are really crummy. The Rubber gasket inside the petcock is called the "whizzer valve", it and the flat metal surface that rides on it can be sanded smooth and reused rather than replacing them. Be aware that most later models have vacuum diaphragms in the back of the petcock(s) to stop fuel flow when the bike is not running. If it is torn, your fuel may not shut off at all and carbs can overflow when bike is parked. Rebuild kits contain new diaphragms. Another alternative is to use a our MANPET, manual replacement petcock) or block off plate and replace the petcock(s) with standard On-Off-Reserve units available with 1/4" or 3/8" pipe tank connections. We can tell you where to get these plates.
  7. Flush out the fuel tank and reseal it with Kreem if it's rusty. Yes, it costs money, the chemicals stink and it takes 2 or 3 days but it's worth it. li>Replace the gas lines and vacuum hoses with new hoses and clamps. Hose clamps not recommended.
  8. Install $2.99 clear plastic inline fuel filters, even if the tank is clean.
  9. Set air screws per your manual.
  10. Balance the carbs with a set of carb sticks after a major tune up. A good time to check for air leaks. Spray carb cleaner or starting fluid around the manifolds and butterfly shaft. RPM should not change. "
  11. Always put Sta-bil or some kind of fuel stabilizer in the gas tank if you don't ride often enough to keep the gas fresh.

Ignition System

  1. Yamaha XS650's are known the world over for having very weak stock ignition coils. Check yours with an OHM meter, per your manual. Aftermarket coils are offer a vast improvement. TCI ignition, not so much, as the black boxes are current-limited.
  2. Spark plug boots can have too much resistance, check yours, look for more than 5,000 OHMS and replace them if needed.
  3. Spark plug wires may or may not be replaceable. If the wire is  held into the coils by a screw on ring you can replace them with the wire we sell. If you have stock single coil with dual leads and no clamp rings, you can't change them without cutting them and using a specially designed splice.
  4. A fresh, clean, properly gapped sparkplug of the correct heat range, BP7ES is always your best bet to start with.
  5. Battery should be well charged, 12.5 - 13.5 volts.
  6. Inspect and clean all electrical connections on a bike that has been out of commission for any length of time.
  7. Lost or non-existing keys can be replaced, contact and Robby will help set you up with new keys for just a few bucks.

Charging System

  1. Check the brushes under the left sidecover and replace them if they are 1/4" long or less.
  2. Check that fuse block under the seat and replace it with individual spade type fuseholders from Wal-Mart at about $2.00 each or go to Radio Shack and buy a universal fuse holder,  pop rivet it in place and solder your wires on to it.
  3. Resistance makes the turn signals work correctly, use only the correct 27W (1156) bulbs or expect problems. Flasher units seldom go bad.
  4. On non-electronic ignition models, the voltage regulator is adjustable.
  5. The diode trio is under the battery box on models with mechanical regulators, remove it and clean the green goo out of it with warm water, dry it well with compressed air and put it back in.
  6. Rotors and stators are easy to test with an OHM meter and expensive to replace. Your shop manual WILL pay for itself many times over BUT they are full of errors on the electrical system. See:
  7. If you have charging system failure and need to keep moving, remove 1 alternator brush and unplug your headlight to prolong battery life.
  8. That battery under the seat should have 12 - 13.5 volts in it at rest. A working charging system will put around 14 volts to the battery when the bike is running.


  1. 1The 650 electrical system will support a halogen headlight but don't expect too much more from it.
  2. Be sure your brake light works.

Cam Chain

  1. Adjust per the shop manual at tune-up time. I like to do it running.

Oil Strainers

  1. Clean it every time you change the motor oil. Check the sump filter for tears.

Oil leaks

  1. The most common oil leaks are between the jug and head (remove the engine and replace the gasket, although occasionally, a re-torque will fix it)) and at the clutch pushrod oil seal under the left side cover, an easy fix-- be sure to chamfer the entry to the hole, as this seal was designed to be replaced by splitting the cases.


  1. XS650 clutches are known to be very particular and require proper adjustment. Engine oil type and weight can affect operation. Use REAL motorcycle oil or diesel oil, not some auto parts store "10W slippery" that is on sale. Castrol GTX is very slippery and not recommended. Yes, good oil costs more but it's worth it. An incorrectly adjusted clutch can cause neutral to run and hide from you at stoplights. That is just not very much fun and it's easy to avoid. Note that the stock clutch cable has insufficient free length and puts the lever arm in a falling leverage ratio. As a result, a full pull at the handlebar lever doesn't move the push rod as far as it could, making the adjustment critical. 650 Central's E-Z Pull cables address this problem.
    Here's how we do it:

General Engine Stuff

  1. OIL: use diesel oil, not automotive oil. The XS has an almost bulletproof bottom end and it's cheap insurance to keep the oil clean.
  2. Valve adjustment is easy to do. Follow your Clymer manual.

Cables and Controls

  1. Lube those cables with a cable lubricator and lubricant designed for that purpose. It's no fun to lose a cable 50-100 miles from home.
  2. Clutch lever free play should be about 1/8", that means a slightly loose feeling lever is OK.

Rear Brake

  1. Clean the rear drum with sandpaper when changing rear shoes otherwise you won't have a good surface for the new shoes to bite into. This also removes the boundary layer of friction material, so it won't contaminate the new linings.
  2. When rear wheel is loosened or removed, hold the brake pedal down in the "on" position while tightening the rear axel to help align the shoes properly and increase rear braking power.

Front End & Suspension

  1. XS front springs were poor from the get-go, shim them up with pieces of PVC tubing or replace them with modern springs. You can seriously upgrade the performance of the 35mm front end with the addition RaceTech's Gold Valve Emulators, to give adjustable compression dampening and blow-off capability. BEWARE the Minton Mod.
  2. You can use 10, 15, 20 or 30 weight motor oil in the front forks, experiment with weights for the feel you like.
  3. The stock steering head bearings, if overtightened can have a "ratchety" feel and can cause front end shimmy. Tapered roller bearings are a quick fix here.

Rear End & Suspension

  1. XS rear shocks were not of much use even when new, Progressive Suspension and a few others make some nice replacement units. Longer 13.5" units recommended, to help with the XS's poor weight distribution.
  2. If you can wiggle the swing arm at all with the bike on the center stand, it's time for replacement bronze swingarm bushings, the stockers are plastic and can wear out quickly. Handling will be greatly improved with the replacements.

Wheels and Tires

  1. Check the tire pressure often, especially after storage.
  2. If it's a mag wheel and it does not have the word "Tubeless" cast into one of the spokes, put a tube in it.
  3. XS650's had various combinations of spoked and mag type wheels, even in the same model year. On a bike that's at least 24 years old now, always replace the tubes and rim straps, they are cheap insurance.


  1. Your 650 is going to require swingarm bushings, steering head bearings and some aftermarket springs front and rear shocks if you are going out to drag the pegs through the twisties.


  1. Aluminum cases can be polished, glass beaded or painted with a good quality case paint. If you are going the paint route, buy the good stuff (PJ1), don't use BBQ paint!

Flat and Street Trackers

  1. The difference between a flat tracker and a street tracker can be as simple as removing the license plate and installing number plates. The XS650 is a popular flat track racer because it has a stout, torquey engine and is inexpensive to modify. The fiberglass bodywork is available from Omar's Dirt Track racing. Contact Omar's at (952) 935-8833 for details.