[llrelease]

I have through existing threads, tried many fixes, and haven't been able solve the problem of my 1982 GL500 overheating. It runs great, but the temp indicator settles about 1/8" outside of the thin "normal" line or a little more than half way to the red zone when riding. Below is a list of the actions taken so far. Am I missing something? Thoughts and suggestions are appreciated!

Troubleshooting / actions to date:

1. Replaced thermostat, temp sensor, and gage
2. Confirmed the fan is not damaged and turns when the motor is running
3. Confirmed thermostat is opening (~10 minutes of idle or radiator temp reaches 182F and gauge is at the high end of the thin line)
4. The sensor resistance is 351ohms at room temperature (86F) and drops to 62 ohms before the coolant starts to boil over
5. The output of the voltage regulator is 7.10 volts at startup and when the engine is warm

I did notice that the sensor resistance drops about 20 ohms if the ignition is switched from off to on when the motor is hot. Could that indicate a grounding problem?

I am also wondering if what I am seeing is normal for this bike during the summer in Charleston, SC. The bike sat for 10 years, and I don't recall it overheating before that.

Thanks!

LLRelease (Bryan)

 

[reclinedrelic]

The gauge on my GL500 is normally past the thin line into the thicker line although it is not 1/2 way to the red end. It gets much closer to the red end when stuck in traffic on a hot day.

 

[Newt]

I think you are chasing a phantom in your mind.

Besides the Temp Indicator reading a pinch high....are there any other signs of overheating?

Remember, the Temp Indicator is not a highly sophisticated instrument with great accuracy. Its just 2 steps above an ID10T light.

 

[llrelease]

There are no other signs of overheating, but the coolant did start to boil after idling for about 25 minutes with the cap off. Maybe that is to be expected on a hot day. What concerns me is that it always ran in the normal range before I let it sit for 10 years. I cleaned the carbs when I got it running again. Could poor carb adjustment cause it to run hotter? I had trouble with the plugs fouling and hesitation before switching to iridium plugs.

 

[Randall-in-Mpls]

A lean mixture could cause the engine to run hot.
Perhaps the temp sender and/or 7v regulator have degraded over time?
When you ran it with the cap off, do you mean the radiator cap? That might be normal with the system unable to pressurize.

 

[llrelease]

Yes, it was with the radiator cap off. How can I tell if it’s running lean? It’s running pretty well, but… One carb seems to take a minute to get fuel at startup. Also, when riding, the motor seems to hesitate between around 4000 and 5000 rpm - especially when it’s not comp warmed up. It feels like it may be lacking power, but that could be because I have become used to riding newer 1200 and 900cc bikes.

The GL500 sat for many years while the kids were young. Restoring and getting it running was a COVID project. I cleaned the carbs by disassembling and soaking all the parts in Berrymans. I did accidentally drop one of the idle plugs in the cleaner and it swelled up. I was able to squeeze it in, but the part that sticks out broke off. It could be leaking.

I love the bike and have put many hours into the restoration. Hoping to get it running like new!

 

[Newt]

Hmmmm.....may I offer a suggestion on the carb.

Purchase Larry's Carb book. It has fine detail on cleaning and assembly of these carbs. Get the repair parts from Randaaks. Sorry, not sure of the spelling on Randaks.....

Get the carbs thoroughly cleaned, adjusted and synchronized (balanced). This will help solve any carb related issues that maybe contributing to the temperature concerns.

Good Luck.

 

[richnct]

Looking at the spark plugs condition is a time honored shade tree technique to determine rich or lean operation. Search “plug chop” for “advanced” method.

 

[llrelease]

Thanks for the tips! I was thinking about getting Larry’s carb book or sending the carbs to him for a rebuild. I will check out Randacks for the parts if I do it myself. glad to have a source other than eBay. I am a competent tinkerer, but I am clueless about balancing the carbs and I don’t have a vacuum gage.

I have put at least 1,000 miles on the bike since cleaning the carbs, so the plugs should provide some insight into any issues. When I first got it running, I had a problem with the plugs fouling and carbon deposits (Running rich?). It ran much better after switching to iridium plugs, but perhaps they just masked any problems.

 

[reclinedrelic]

I am clueless about balancing the carbs and I don’t have a vacuum gage.

The carbs can be balanced using a homemade manometer which even these days should cost less then $20 to make.

 

[Sidecar Bob]

the temp indicator settles about 1/8" outside of the thin "normal" line or a little more than half way to the red zone when riding.

I don't understand the problem. The wide part of the line is the normal zone. As long as it doesn't approach the red area to the right of the normal zone your engine is not overheating.

 

[Randall-in-Mpls]

The carbs can be balanced using a homemade manometer which even these days should cost less then $20 to make.

Even a bench sync (done visually, while reassembling) will get balance pretty close.

 

[richnct]

Yes, I’ve bench balanced two sets of carbs this summer and when afterwards I put vacuum gauges on them no further adjustment was needed. My method is to adjust the idle screw so the master throttle plate barely shows the first bleed hole and adjust the other to match it. I use the very slightest amount of the hole visible as possible for accuracy. Then later I’ll adjust the idle to 1100 rpms. Works well for me and I’m no master mechanic. Done carefully bench balancing is normally fine for the non-perfectionist. IMHO

 

[Newt]

@llrelease

You don't need a vacuum gage to balance the carbs. A simple U-tube manometer will be accurate. This complex device can be made from a length of clear vinyl clear tubing and a tape measure. You can look this up on the Inet for the "How To Build"

IIRC, the the left carb is the Master carb (no adjustments for balance), the right carb is Slaved to the Master. The balance specification is within 1 inch of mercury. Use water in the tube, the conversion for water is 13.6 inch of water. Call it 13 inch of water for the balance specification.

 

[llrelease]

I will try to check and balance the carbs. Where is the first bleed hole and how can I see it? It seems I have a lot to learn! I will read through the shop manual and buy a copy of Larry’s carb book.

ls it correct that the thick line on the temp gage represents the normal operating temp? I always thought it was the thin part of the line.

Thanks for the help!

 

[Sidecar Bob]

Page 19 of the '81 GL500I Owner's Manual (I've attached the PDF in case you don't have the book). I doubt the standard or the '82 is any different.

 

[Newt]

I will try to check and balance the carbs. Where is the first bleed hole and how can I see it? It seems I have a lot to learn! I will read through the shop manual and buy a copy of Larry’s carb book.

Thanks for the help!

There is a small screw located on the bottom of each intake runner next to the cylinder head. The runner leading from the carb to the head.

If you use a U-tube manometer, you will need to connect one leg of the U-tube to the Master and the other leg to the Slave. This will allow a direct reading of the balance difference between the 2 carbs.

 

[nolimitz]

On the GL the are on top/side of the carb intakes

 

[Sidecar Bob]

I thought they were on the top of the intake manifolds on both models.

And where did "slave" and "master" come from? One is left and the other is right...

 

[Newt]

Ok.....I got the wrong side of the intake runner. Haven't balanced carbs since 2011. Memory fades with age and libations.

Master/Slave is from which carb is non-adjustable and which is adjustable. IIRC, the Master/Slave terms are in the How To section to balance the carbs.

Left carb does not have balance adjustments, therefore it is the Master. The right carb has balance adjustments, therefore it is Slave (dependent) on the left (Master) carb.