Annual Oil Change

Mileage: 29,509

Maintenance Summary:

  • Changed Oil: Rotella T4 15W-40

It’s been one year since the oil was changed, so it’s time.    As it’s only been 1600 miles since the last change, the filter was not changed with this service.  However, the filter canister was loosened to drain the oil around the filter.

New Front Master: Quality This Time

Mileage: 29,469

Maintenance Summary:

  • Installed New Front Brake Master Cylinder (14mm)
    • Shindy 17-652B
    • Replaced fluid  Prestone DOT-4
    • Bled brake

The eBay special $18 direct-from-China master cylinder is off the bike after only 15 miles.   The quality of the part was so poor that I didn’t want to continue to trust my life to it.  The Shindy set me back almost $140.

I was pleasantly surprised that the braking improved a bit with the Shindy.   While not a huge improvement, it is better.  I’m not sure why it’s better as it’s not obvious that the Shindy has any more mechanical advantage — lever lengths are similar — and both pistons are spec’d at 14mm.

Installation was easy, as expected.  The brake wiring, mirror and brake line/banjo bolt swapped over without any problems.   I did have to rotate the hose nipple on top of the master cylinder to allow the hose to reach the reservoir without kinking.

The only problem that I ran into was with the initial brake bleed.  I think it was probably air in the hose going to the reservoir that prevented me from pumping the brake to bleed the system; brake fluid simply wasn’t getting to the cylinder.  I ended up pulling a vacuum at the caliper to get things started.  After that I was able to complete the bleed using the brake-pump method.

Temp Gauge Repair with DIY Regulator

Mileage: 29,453

Maintenance Summary:

  • Repaired Temp Gauge with new DIY 7V regulator

The temperature gauge on this bike has been intermittent since I bought it.  Once the weather turned cold it rarely seemed to work.  Having found no other reason for the gauge not to work I decided to replace the regulator.

It would cost more than $50 to buy the OEM Honda part — which is available.  Normally I would go with the original part.  However, besides being ridiculously expensive for what it is, electronic parts degrade over time, even when not in use, and the OEM parts have probably been sitting on a shelf for a few decades.  So, instead of buying the OEM part, I built a new regulator for less than $5 using a 3D printed case and an adjustable buck regulator I purchased on eBay.

I’ve described how to build the regulator that along with some troubleshooting and gauge operation info  here: DIY 7V Regulator.

Here’s the regulator just before it was bedded it in the case with epoxy.

3D Printed case and Mini-360 DC Buck Converter

The new DIY regulator is a direct replacement for the OEM regulator.  Here you can see the new regulator hanging in the original rubber mount under the speedometer.

Only time will tell if this is a robust solution to my temp-gauge woes, but it’s looking good so far!

New Front Master: An Experiment

Mileage: 29,451

Maintenance Summary:

  • Installed New Front Brake Master Cylinder (14mm)
    • Replaced fluid  Prestone DOT-4
    • Bled brake

Having only one other, even older motorcycle to compare to, I hadn’t really had any concerns about the front brake on this bike.   It seemed to work just fine, that is until I began riding a more modern bike, one actually built in this century.  Now, the front brake feels stiff and wooden — almost broken.

The master cylinder that came with the bike is not original equipment so the question in my mind was, did the person who installed this select a suitable part with the correct cylinder size?   Lacking in any markings to indicate cylinder size I can’t answer that without taking the thing apart.  Rather than do that, I decided to install a new master cylinder known to have the correct cylinder size and see if the braking is improved.

Bike came with an aftermarket master cylinder. Cylinder size unknown

One of the reasons that someone might install the wrong part is that the Honda repair manual appears to have a typo.   In the table, a smaller master cylinder size is specified for the GL500I Interstate model with twin rotors, while a larger cylinder size is specified for the single-rotor GL500.  The reason that this table is suspect is that the calipers for two rotors should require more brake fluid volume from the master, not less.

This bike is the non-interstate model with a single rotor, so the 14mm size would seem more appropriate. Even if the table is correct, going from a 15.87 mm cylinder to 14mm — if that’s what I’m doing — should result in a lighter brake feeling (i.e. more hydraulic leverage).  That said, the front caliper has two 30mm pistons for a total piston surface area of 2xPI*(30/2)^2 = 1413 mm^2.   A 14mm master has a surface area of 153.86 mm^2 giving a caliper-to-master ratio of 9.2.  That’s not a lot of leverage compared to a modern bike.  For a 12:1 ratio, we’d want a master cylinder size of 12.2 mm.  So, if this experiment fails to improve the braking,  I think I may try and find a 12-13mm master.

There is an argument to be made for requiring higher lever pressure (four finger braking instead of two).  In a panic, you’re less likely to lock up the brakes.

The Honda master cylinder with the angled reservoir is no longer available;  if it had been I would have bought that part.  In my search for a new master with a 14mm cylinder, 7/8″ handlebar, mirror mount and integral brake switch I seemed to have three choices:  really cheap ($18 eBay from China,  more expensive but no indication of better quality than the really cheap option, and very expensive ($140 Shindy).  As this is a bit of an experiment, I went with the $18 option as the part looked very much like the part that was on the bike.

While this new part looks nearly identical, it’s not.  In fact it looks even less refined than the cheap master that’s on the bike.  Here’s what it looks like installed.  If you look closely, you’ll see that the right cover screw isn’t flush.  That’s because the hole spacing in the lid doesn’t match the hole spacing on the main body.   Fortunately there doesn’t appear to be any operational problems with the cylinder and piston.  Unlike the original Honda master with an angled reservoir, the reservoir cover on this part isn’t level to the ground when the wheel is centered, so I’m relying on the cover’s seal more than I would like to keep fluid in the reservoir.

Service Hint:  Put the bike on the center stand and turn the wheel to the full left stop before opening the reservoir; it’s more level in that position allowing you to get more fluid in.  It’s also less likely to spill when opening, and it’s further away from the paint on the gas tank if you do spill.

New master cylinder

If this master works better than the old one then perhaps I’ll eventually buy one of these spendy-Shindy model 17-652 ( 17-652B for black) master cylinders.  With the separated fluid reservoir and adjustable bracket, it should be possible to obtain a better fit relative to the angle of the handlebars.  Note that the Shindy has the required integral brake switch and mirror mount.

Shindy 17-652 or 17-652B

Test ride results: No improvement, unfortunately.

Compression Test and Plug Inspection

Mileage: 29,424

Maintenance Summary:

  • Performed Compression Test (engine slightly warm):
    • Left: 158 psi
    • Right: 160 psi
    • Spec: 171 +/- 20 psi

Some time ago I borrowed a plug adapter from a friend so that I could perform a compression test; my compression gauge didn’t have an adapter that matched the plug size for this bike.  As I’ve had the borrowed adapter in my possession far too long, today’s task is to perform a compression test so that I can reunite the adapter with its owner.

The only reason for performing this test is regular maintenance.   I’ve no reason to suspect that anything is wrong with the bike.

I only warmed the engine up on idle for a few minutes.  The cylinders were warm, but not hot.

This isn’t an expensive gauge, so I don’t know how accurate it is.   At 90 psi, it reads about 5 psi lower than another cheap gauge I have on my air compressor.  Still the compression readings are well within spec, and very well balanced — the most important thing.  Even a cheap gauge can be used to check if one cylinder has lower pressure than the other.

Right Cylinder @ 160 psi
Left Cylinder @ 158 psi

The plugs look good, especially considering that I pulled them after a few minutes of warming the bike from cold with the choke on.  I would have preferred to look at these after a good run, but it’s cold and wet outside.

Left and Right plugs

Cleaned, Inspected, and Greased Side Stand

Mileage: 29,424

Maintenance Summary:

  • Greased the side stand with moly grease.
  • Replaced missing 10mm nut (5/31/18)

The side stand is not as tight fitting as the center stand.  I don’t know if that’s the way it came from the factory, or it’s not tight because of a bit of wear.  The side stand is more heavily used, it’s under more stress (only one attachment point and heavy side stresses), and it’s probable that the stand hasn’t received regular maintenance.  That said, this simple design is very rugged and can take a lot of abuse.  While it might be possible to force some grease into the pivot bolt hole without removing the side stand, I chose to remove the side stand for a thorough cleaning and inspection.

To gain access to the side stand pivot bolt I dropped the entire exhaust system.  I did this by removing the header clamps, removing the bolts at both ends of the power box (three bolts total), and removing the two rider peg bolts.  This allowed the entire exhaust system to be lowered as shown here.

The side stand and pivot bolt were completely lacking in lubrication.  The stand is also missing a 10mm nut.  The stand is threaded so the missing nut is supposed to be there to lock the pivot bolt and keep it from spinning loose.  I’ll install the nut later.  (Update: Nut installed 5/31/18)

Below is the frame tab that the pivot bolt passes through.  The inner surfaces of the hole, the top of the tab on the outside, and the bottom of the tab on the inside is where most of the wear occurs.  If you enlarge the picture below you’ll see that the portion of the tab above the hole has wear not visible on the section below the hole.  You can also see the bit of bailing wire that I used to remove and reinstall the spring.

Hint:  Install the stand in the down position.  You won’t be able to lift the exhaust past the side stand if installed in the up position.  See the first picture to understand why. Install the spring after the exhaust system has been reinstalled.

Reinstalling the exhaust system was a bit of a pain and took some time.  The entire job took about an hour.

Installed new carb plugs and Misc. O-Rings

Mileage: 29,424

Maintenance Summary:

  • Installed new rubber plugs in carbs
  • Installed new o-rings in carb isolators
  • Installed new o-rings on both timing and crank adjustment caps

After re-installing the carbs which were removed to access the top rear shock pivot bolt, the bike seemed to be running very lean.  When I rebuilt the carbs  I didn’t replace the rubber plugs inside the bowls.   The plugs were in poor shape, and I was always worried that small pieces of rubber would find their way into a jet.

Having found some aftermarket plugs on eBay, it was time to pull the carbs — again.  Here one of the old plugs alongside the new.  Click on the picture to enlarge.The installed plug is near the center of this picture.  I did find one partially clogged jet.

Another possible cause for the bike running lean is an air leak at the junction between the carb insulators and the cylinder heads.  I didn’t bother to test for a leak, I just replaced the o-rings at that junction when I re-installed the carbs.

Two other o-rings that were replaced today seal the adjustment caps, or covers; the timing cover shown here always had a bit of oil around it.  There’s another identical cap between the clutch and the oil filter on the front of the engine.

The o-ring sits in a groove on the back side of the cap.  The new part seemed to be slightly undersized in terms of diameter.

After putting everything back together I took the bike for a short run.  It’s running great again!  The only problem that won’t go away is one where the temperature gauge sometimes doesn’t work.  I’m starting to suspect that the 7V regulator is intermittent.




Greased Center Stand and Rear Brake Pivot (shaft)

Mileage: 29,404

Maintenance Summary:

  • Greased center stand and rear brake pivot shaft with moly grease.

Often there are maintenance items that owners will ignore, even those who religiously perform other maintenance such as changing fluids.   While a poorly maintained center stand may not result in a crash, it can result in a more expensive repair after the miles start to pile up.  This diagram shows all of the various locations on the GL500 where lubrication is required.

Today’s task is to grease the center stand and the rear brake pedal pivot, which is a shaft that transfers the brake pedal motion from the right side of the bike to the left.

Unfortunately, the side stand bolt interferes with the exhaust system (power box), so I’m saving that maintenance task for another day.

As you can see in the next picture, the center stand pivots have not been lubricated in some time.  One of the reasons that people shy away from this task is the challenges of removing and re-installing the spring.  Honestly, it’s not that hard.  I used a breaker bar as a T-handle to pull on a bit of wire hooked over the end of the spring to both remove, and re-install the spring.  In the past I’ve also used vice grips.

I cleaned off the rust and corrosion using a wire brush, Scotch bright pad, and kerosene before greasing the moving parts and re-installing.  These parts support the entire weight of the bike when you’re putting it up on the center stand, more if you’re on the bike.  So they can wear if not well lubricated. Fortunately, while these haven’t been serviced in a while, the center stand doesn’t exhibit any wear.  It still feels tight.

Here’s a look at the underside of the bike with the center stand removed.  You can also see the side stand — which appears to be missing a lock nut.  Unfortunately the side-stand bolt can’t be removed with the exhaust in place.

The brake pivot was also greased.  All thats required to do this job is to remove the rear brake pedal from the right side and then slide the shaft out on the left side of the bike.  It will clear the frame.  I completely removed the shaft from the bike and then cleaned and greased it before re-installing.

As you can see, I removed the link rod going to the rear brake before pulling the pivot shaft.  The easiest way to do this is to first disconnect the link rod at the rear brake.  This allows the pivot rod to rotate making it easier to access and remove the cotter pin.

The pivot shaft isn’t under that much pressure, but it does have a lot of surface area.  Grease will ensure that the brake operation is smooth and that corrosion won’t cause binding.


Greased Rear Shock Upper Pivot Bolt

Mileage: 29,404

Maintenance Summary:

  • Cleaned and greased rear shock upper pivot bolt with high-moly grease.

When I recently serviced the rear suspension the one thing I didn’t do was service the top pivot bolt on the rear shock;  I couldn’t figure out how to get to it.   According to the service manual you can service the bolt without removing the air box.  Frankly, I couldn’t see how.

Look for the red arrow near the center of the picture below to find the bolt in question.  Here I’ve managed to get a socket on the bolt head using an socket extension and universal joint.  The extension passes through a narrow gap between the airbox and the frame.  Now, it might be possible to remove and re-install this bolt through this gap without removing the airbox (or carbs), but I don’t see how.

Note:  The nut on the left side of the shock is fixed in place making this job a bit easier.

The carbs are easy to remove on this bike, easier than the air box, so that’s what I did to gain easy access to this bolt.  The bolt was in very good shape with a little bit of old, very dry grease remaining.  I cleaned the bolt and coated it with high-moly grease before re-installing.

Note:  It’s a lot easier to remove and re-install this bolt with the rear wheel supported just enough to remove pressure from the bolt.  I used a block of wood and a large screwdriver under the tire.  When the bike is on the centerstand, the shock supports the rear wheel.

I have the seal required to rebuild the rear shock.  Those are no longer available from Honda, but I found a NOS part on eBay.  Since the shock is still holding air reasonably well I’ve decided not to attempt to rebuild the shock at this time.  Many people replace this shock with something else rather than rebuild them.

Fan, Tach Cable and Camshaft Seal

Mileage: 29,404

Maintenance Summary:

  • Replaced the following items:
    • Fan
    • Camshaft seal
    • Camshaft holder gasket
    • Camshaft holder o-ring
    • Tachometer cable and keeper screw.

While I had the front wheel off to rebuild the front forks, I decided to pull the radiator and fan so that I could replace the tachometer cable.  Well, as often is the case, once I had everything apart I found a few more items that required attention.

I pulled the fan using a 14mm bolt and the threads on the fan provided for this purpose.  It took a bit of work to get it to pop off the tapered shaft, but with a bit of pressure from the bolt and tapping on the end of the bolt with a hammer, it finally gave way.   The first thing I looked for was cracks in the fan — a common problem on this bike.   Sure enough, every rib has radial cracks extending from the aluminum hub.

Left unchecked a cracked fan has the potential to fail catastrophically and damage the radiator.  After briefly considering converting the bike to an electric fan, I decided to keep the bike original.  These fans are still available from Honda, and relatively affordable at $30.  Thank you Honda! I probably would have switched to an electric fan if the conversion didn’t require cutting off the end of the camshaft, or the fan was no longer available.

The cracked fan isn’t the only problem I discovered.  As you can see in the next photo, the camshaft seal and possibly the camshaft holder gasket have minor oil leaks.  As these two parts add up to less than $6, they’re getting replaced as well.

In the picture above I’ve already removed the Phillips-head screw that holds in the tach cable.  That screw was difficult to remove, especially with the fan shroud in place so, as others have suggested, I’m replacing it with an M5x20 cap-head screw.

With the camshaft holder removed, it’s easy to see one of the cams and lifters.  The screw gear drives the tachometer.

Here are the new parts.  The two o-rings are for the fork caps.
The new fan looks exactly like the old one — minus the cracks.

One of the things I discovered after removing the camshaft holder was that there was an o-ring seal that needed to be replaced.  This seal isn’t easy to find in the fiche.  I didn’t even know it was there before I pulled the camshaft holder. Fortunately the local Honda dealer had the part in stock.

I was able to remove the camshaft seal from the holder with my fingers.  It came out with very little effort.  The new seal went in just as easily.  The seal could have been easily replaced without pulling the camshaft holder — if that’s all that’s required.  Here’s the old seal and the new gasket.

Reinstalling the camshaft holder required turning the crankshaft until the pressure on the camshaft was such that the shaft was centered.  This was easily done by removing the cover near the oil filter and slowly turning the crankshaft bolt clockwise until the camshaft holder could be pushed in.  After sliding the holder most of the way in, I continued to spin the crankshaft to allow the tachometer gears to mesh as I fully seated the holder.

With the camshaft holder installed, I then installed the new tachometer cable and used a cap-head screw to hold the cable in place.  I then installed the fan and re-installed the radiator. I used blue Loctite on the holder bolts, tachometer cable keeper screw, and on the fan bolt.