Here at SuperXparts we are committed to providing accurate information about what goes wrong with the Super X, as well as the best ways to avoid repair problems.  We welcome your input and experiences too.   

We have found that if the upgrades are done early and a good maintenance program is followed, the Excelsior Henderson is a very reliable machine.  

The transmission repair is essential because of the potential for harm, but the real issues with the Super X are caused by heat, tuning and incorrect belt tension.  Vibration also plays a part, but you can begin to minimize it by taking care of the first four. 

Here is a breakdown of what can happen, what needs attention, and why:


The bushing clearances are too loose on the bushed gears.  This allows the gears to rock and strain the retaining clips.  Most failures happen at the 4th input gear when the clip breaks, allowing the gears to slide out of place and lock up the transmission.  The gears have to be re-bushed with tighter tolerances.  Double wound clips help insure they will not break again.  This problem is also a source of vibration.   If you do not get your gears rebushed you have only done half the repair. 

There is also that annoying false neutral you get when downshifting.  It is caused by the shift pawl arm failing to make positive contact with the detent in the shift wheel.  A redesigned wheel with recut detents and a stiffer spring will fix it.


Install a fan forced oil cooler.  High oil temperatures can lead to premature wear on the motors moving parts and cut it's life in half.  Also switch to a premium synthetic oil. We use Amsoil.   Most motor lock-ups are because the onan type steel main bearing  spins in the aluminum case and either cocks or blocks the oil feed hole.


Our ECM manages the fuel, spark, and timing.  The stock tune is a ticking time bomb.  It was developed to pass the EPA regulations and is set to run much too lean.  Even worse, it has a feature that samples the fuel mixture and  resets the air/fuel ratio lower and lower as you ride.  The longer your ride, the leaner the fuel mixture becomes.  That is why, when you finally come to a stop, it stalls.  When you restart it, the fuel map resets to the last average.  Eventually your bike will run lean all the time.  This causes the cylinder heads to overheat, burn valves and crack heads.  We see this time and again.  If you are close to 25,000 miles, get a compression test.  This seems to be a benchmark mileage for valve jobs.  

Get your ECU loaded with SuperXtune as soon as you can.  One long trip is enough to set your bike up for an eventual valve job.  Plus, it will just plain run better.  Almost every owner who  does this calls us back to say their bike never ran so good.

The SuperXtune program is no longer available to individuals, but by removing your ECU and sending it to us it can be loaded with the software. 

Belt Tension:

Incorrect belt tension is responsible for problems from the front motor mount isolators to the rear wheel hub.  If it is too tight you will consistently break your motor mount isolators.  It also contributes to wiping out your rear wheel hub.  Every time you accelerate your pull the rear axle and bearings against the already too soft cast aluminum hub, eventually eating it away.  check out the pictures below.  Remember, the belt tightens when you sit on the bike.

Belt noise on acceleration  indicates it is too tight.  Noise on deceleration indicates it is too loose.  Sitting on the bike, reach down and twist the belt--it should twist a minimum  of 90 degrees.  Better yet, put a wrench in your pocket and go for a ride, stop and move the adjustment till you are satisfied.  Be sure you squared the axle correctly.  Don't waste your time with tension gauges.


Motorcycles vibrate and things shake loose, like your battery cable and ignition switch assembly.  Perform a "Torque Wrench Walk-around" periodically as part of your maintenance routine.  Replace your flimsy ignition switch bracket with a heavy duty one.  Install a Stavos kit to keep your switch together.  A more flexible battery cable will also help.

Check your wiring harness from time to time too.  The wires are bound up pretty tight and it is easy for them the rub each other or the nearest hard material.  Some wiring benefits from additional shielding, like the bundle that runs from the electronics area to the front of the motor.  Those wires are partial to rubbing open where the harness runs under the motor in the back .  Check the routing on the two wire harnesses from your handlebar switches.  They can get damaged where they are threaded  through the forks to the frame rail and under the fuel tank.

Another good thing you can do is install our Custom Motor Mount Nuts.  They do a better job of pulling the engine mounting system together which helps eliminate some vibration.  


If you cannot do everything at once, we recommend you do these things as soon as possible.

1.  Fan Forced Oil Cooler
2.  Performance Air Filter Kit
3.  SuperXtune
4.  Auxiliary Ground Strap
5.  Transmission Upgrade
a.  Oil Pick Up Tube
b.  Install Viton O'Rings in Slave Cylinder
c.  Flush Hydraulic Fluid
6.  Change to Synthetic Oil


Before you even think to try and start the bike, take time to check out the Vehicle Set Up procedure recommended by the factory.  

Many bikes were never pre-delivered by the original dealers so folks with low miles might also want to take a look too.  All bikes, regardless of miles will benefit from an occasional "Torque Wrench Walk-around"

1.  Charge the battery.  They are old now but the original  Yuasa has 
     been  surprisingly durable.  If you replace the battery, be sure it is the correct          size.  The original Yuasa YTX20 H BL is the only one that fits properly.
2.  Remove the fuel tank and hose to the throttle body.  Remove the fuel pump             and gauge sending unit.  Inspect them carefully.  If gummed up, soak in                   parts cleaner or fresh gas and clean carefully.  If rusted up you can replace             the  electrical pump unit and the pressure regulator.  Rinse the tank out with 
       your garden hose.  Make sure the red lining has not been compromised and 
       pulling loose.  Dry thoroughly.  Put a new fuel hose on.  Install gas with
       the highest octane rating you can find.  Install a fuel system cleaner.  We
       like Amsoil PI.  You may also need to have the injectors cleaned or replaced.
3.  Change the engine oil and filter.   
4.  Check your tires.  They are now 28+ years old and though they may look OK,            chances are once you ride the sidewalls will develop small cracks.  It is                    best to replace them.   They are also dry and hard and ride is affected. 
5.  Flush the hydraulic fluid in the brake and clutch systems. Use DOT 5
6.  A quick check for your belt tension:  Sit on the bike and (you may want to
      have a helper) and twist the belt 90 degrees.  If you can, good.  If you cannot
      it is too tight.                          
7.  Lube your throttle and idle cables. 

If your fuel tank continues to shed the liner or rust, contact us.  We now have a way to strip the old lining and rust without damaging your paint.

Start it up and take a ride.  Follow the rules for breaking your engine in properly. This information can be found in your owner's manual.    If you did not get one, we still have a supply for sale.  

Once you have 2500 miles and are due for an oil change, plan to switch to a good synthetic like Amsoil.  Nothing is too good for our bikes.  Now would be a good time to schedule your bike with us for the Super X Solution Upgrade Package.

If transporting your bike on a trailer, never tie it down on the handlebars.  This collapses the riser bushings.  Get some soft ties and thread them through the rigid fork.  Also do not tie it down with the kickstand down.


One of the first things you need to learn is the proper procedure for checking your oil level.  

You long-time owners would be surprised how many folks do not know about "The Rain Dance".  We purchased a bike off a dealer that had a locked motor because the new owner picked his bike up, rode it home, checked his oil the normal way and added 3 quarts.  UH-OH, it hydra-locked up 20 miles later doing internal damage.

So, here is the "Rain Dance", as it is affectionately called, right out of the original factory Service Bulletin.

By the way, if your kickstand is badly bent, your oil level reading will not be correct.

1.  With the engine at normal operating temperature, mount the motorcycle                 and  bring it to an upright position on level ground.
2.  With the transmission in neutral, start and run the engine at 2500-3000                   RPM for 30 seconds.  Shut the engine off while the motorcycle is in the                   upright position.*
3.  Rest the motorcycle on the sidestand and on level ground.  Remove the oil               filler cap and wipe the dipstick clean.  Reinstall the dipstick and turn the                 cap clockwise until it seats.
4.  Remove the dipstick again and note the oil level.
5.  If necessary, add or remove oil to bring the level on the dipstick to the                      second X above the ADD mark.*

 *The RPM at which the two oil pumps are balanced is 2750.  Only folks with SuperXtune will be able to hold this steady reading.  The stock tunes fluctuate.

  *We recommend the 2nd X above the ADD mark.  More than that and you get excess oil foaming--which contributes to oil puke.  

Installing an oil pick up tube also helps keep oil levels better regulated in the 5, yes 5, chambers in your motor.  The reason for the "Rain Dance" is to equalized oil levels prior to checking or changing the oil.

Information Department
This Piston got so hot it melted                      Heat discoloration on the timing 
Wiped out crankshaft                                        Rod cap  from same
This is where all the metal landed                     Spun rod bearing
Eroded Rear Hub                                            The Black Powder of Death
Stator, Regulator, Starter, Crank
Sensor Harness Rubbed Through
Electronics area Meltdown.
Bike was Cutting Out on Acceleration
The Fuel Injector Wiring  Rubbed 
Against the Accessory Switch
Wiring Inside the Harness and They Fused Together.
Beginning to Take the Harness Apart, Yellow/Blue is # 1 fuel Injector
What Goes Wrong and Why

Check out these pages too.
Miscellaneous Things You Need to Know

Most of the fasteners (bolts and screws) were coated with a material called Pre-Coat 80. a type of red locktite.  Instead of a single drop, they were actually dipped in the stuff.  This makes removing them the normal way very difficult and discouraging.  We recommend you  invest in a mini-torch.  Heat is the only thing that breaks the chemical bond.  You need to hold targeted heat to the fastener for at least 40 seconds, 2 minutes on brake rotor bolts, 

We see a lot of stripped oil drain holes.  Be gentle with the drain plugs.  Our cast aluminum cases are a little too soft and it is easy to pull the threads.  If you do have a stripped plug we have found the best way is to install a steel insert in the existing hole.  Unfortunately, it requires purchase of a special tool kit so know ahead of time it can cost you a little over $130.00 to repair.  Call us for the details if faced with this particular problem.

When you can, we recommend you replace any torx head fasteners with a good stainless steel Allen head.  Stainless is better looking and easier to maintain.  Allen head fasteners are easier to work with and it is far less likely the head will strip out.  We also carry a good selection of polished stainless ARP 6 point flange bolts to replace the brake rotor, pulley, front suspension rocker, caliper mounting and fender strut fasteners.  They look great and are indestructible when compared with stock parts.  It is best not to change out the original socket head fasteners that have E-H inscribed on them.  This will hurt the value of the bike when it becomes an antique.

You can improve the sound of your stock mufflers by removing the two center freeze plugs.  Remove the muffler, stand it on end on a block of wood and put a dowel or pipe or piece of rebar down through the center--hit it with a hammer until you feel the plug give way--then on to the second one.  They will shake out if they don't fall out once they come loose.

The clutch and brake fluid is DOT 5, a synthetic mix.  Do not ever put anything else in.  If you do, the seals in the master and slave cylinders will melt.  Also, the rubber in the clutch and brake lines will melt.  You will end up with a black goo in the hydraulic systems and eventually--no brakes or clutch.  

Take time to check your wheel spokes and nuts.  Broken spokes are showing up more and more.  We have spokes and nipples for sale but unless you are weird like us, I doubt you want to learn how to respoke and true wheels.  Catch this problem before it happens.

Folks often comment on oil seepage at the head and base gaskets.  Unless it is a very active leak, we recommend leaving it alone until you have a more pressing reason to take the top end apart.  Re-torqueing the head bolts will probably not help so don''t consider it as it can actually cause problems.  The cases are softer than we would like and when removing or tourquing down head bolts there is always the danger of pulling the aluminum threads--which leads to a cascade of repairs.  It is actually a design flaw that cannot be corrected without taking the heads and jugs off.  Even then you will need the aid of a machinist.  Give Jamie a call if you want to discuss it in detail.  If you remove the cylinders you will need to install new rings and have the cylinders dressed. 

Cam covers can leak too and that is much easier to repair yourself.  It is usually the rear one so be prepared to put a floor jack under the motor and remove the front motor mounts and rear motor mount shaft so you can lower the motor for access.  We often find one of the internal bolts that hold the chrome spacer down over the exhaust ports has backed out and is laying in the head.  Occasionally the bolt gets caught up and thrown around, which usually breaks the cam drive chain.  Most often it is just laying to the side.  This is probably the most common cause for leaks. Another common problem is that the chrome spacer was not properly planed when new and there is a small ridge on the bottom that keeps it from laying flat.  We have all ours re-planed and can trade you out if you find yours is one of the problem ones.

The oil pressure switch is also a common place for leaks.  They blow out through the center.  This is one part we recommend you carry with the bike at all times.  Include a socket or wrench to change it out too.  Don't tighten the nut too much--this seems to be part of the problem as it stresses the switch.

Do not block off your idle air control valve or bend your throttle stop.  This was an old trick to enrich the fuel mixture but it has long-term consequences.  Eventually the idle control valve fails and/or it burns out the IAC circuit in the computer.  

Do not shim your oil pressure relief valve.  This too was an early idea to increase oil pressure to the transmission.  It was a bad idea then and still is.  Even the reasoning for doing it was wrong.  The relief valve is there to relieve oil pressure at cold start so the thicker oil does not blow seals and gaskets--after that it's duty is minimal.  That is why it is called a pressure relief valve.

Be careful when adopting ideas found around the internet.  There was a great deal of experimentation and back-and-forth in the early days.  Some things can actually harm your bike.  If you have any questions please call us and we will be happy to share what we know.  Remember, we have been working on Excelsior Hendersons exclusively since 2000, seven days a week, 10 hours a day.  We really do know what we are talking about.

Keep your battery charged.  Trickle chargers are inexpensive and quick to use. The failure of many stators is because folks try to start their bikes too often with an undercharged battery.  

We see way too many replacement tires installed backwards to the rotation arrow. This is probably because the installer does not read or pay attention to the location of the driven pulley.  When getting tires changed, make sure they are the correct size and that the installer understands the set-up of the bike.  We also see front tires installed on the rear wheel.  The narrower profile make for a very squirrelly ride and is even dangerous.  The correct size is MT 90-16 on the front and MU 90-16 on the rear.  Dunlop, Avon and Metzler all make tires that do well on the Excelsior Henderson,  If you want to move to a slightly wider rear tire that won't have any interference problems check with us.

Always have a new tube put in and make sure it is the correct tube.  Our wheels have an offset valve stem so the tube must too.  We actually see bikes in the shop where a tube w/a center mounted valve stem have been installed.  They are almost always leaking.