Honda CX 500 Forum banner
1 - 20 of 23 Posts

·
Registered
Joined
·
103 Posts
Discussion Starter · #1 ·
If I sit idle for about 5-10 minutes after getting the temp gauge up to halfway, the needle will go about 3/4 of the way up. Is that normal? And at what point do I need to be concerned enough to turn the bike off and let it sit?
 

·
Registered
Joined
·
710 Posts
What is your antifreese level at? have you checked your level at the radiator cap? dont always go by the reservior as its not the most accurate at least thats what i found out. Any ideas on when the last thermostate change was made on your bike? that would be first thing I would check. My bike the thermostate gets to the middle as in normal temp and moves stightly down then back to middle normal operating temp as the thermostsat opens and closes. I just changed my thermostat on the bike even before it pretty much stayed in the middle. Let us know what ya find. good luck
 

·
Registered
Joined
·
210 Posts
Only if stuck in traffic does mine head over that far.. My bike does as LB's bike does, gets just into the thicker white band then down a touch then back into the thick white part normally sitting pretty much vertical..
 

·
Registered
Joined
·
4,104 Posts
As a rule of thumb

I'd say anything after 3/4 is getting too hot

there are various aspects and conditions to consider but

checking the coolant level has to be number one.



most gauges seem to sit at the junction of the thin/thick lines

in normal use but may creep up on hot days, traffic riding, idling etc.



a failing 7V regulator or bad contacts may overdrive the gauge and make it read high

and there are various mechanical conditions which may cause the bike to run hotter



If you have concerns about the cooling system

Checking the coolant level in the rad and then the 7V reg is a good place to start.
 

·
Registered
Joined
·
2,601 Posts
Yup, sounds a bit hot to me too unless you're stuck at a light. That's the advantage of converting to an electric fan, it'll run fast enough to keep it cool while the conventional fan is only running at idle speed and since it runs off the cam it's only running at half the rpm of the engine.



If your 7V regulator is going out I've still got plenty of kits with the true 7V regulator IC kits left, just e-mail me.
 

·
Registered
Joined
·
1,265 Posts
If I sit idle for about 5-10 minutes after getting the temp gauge up to halfway, the needle will go about 3/4 of the way up. Is that normal? And at what point do I need to be concerned enough to turn the bike off and let it sit?


A few questions,



1) What is the ambient temperature when this happens?



2) Were you running the bike "at speed" prior to sitting at idle for 10 minutes?



3) When you return to riding, does the guage go back to normal after a few minutes?



So if is 90 degrees outside and you have just come off the freeway, and now sit at idle for 10 minutes, I would say



it is a "normal" condition under those circumstances.
 

·
Registered
Joined
·
103 Posts
Discussion Starter · #8 ·
I recently had all the bike fluids replaced at a local shop. Before you ask, I don't know if it worked the same before the shop did their work because the previous owner drove her straight to the shop following my purchase--never road the bike prior to service.



So I did some research on other posts and I'm suppose to take the radiator cap off while running? Something about burping it and verifying the level. Does everyone agree?



The temp here is about 65 during the day and I ran her for about 30 minutes at 45-50 mph and whenever I hit a red light she starts to creep up. The gauge always goes down when I start moving for at least 5 minutes.



As far as the voltage regulator--is that also called the voltage rectifier?
 

·
Registered
Joined
·
8 Posts
So I did some research on other posts and I'm suppose to take the radiator cap off while running? Something about burping it and verifying the level. Does everyone agree?



The temp here is about 65 during the day and I ran her for about 30 minutes at 45-50 mph and whenever I hit a red light she starts to creep up. The gauge always goes down when I start moving for at least 5 minutes.


I just bought a 1983 CX650C about a week ago and had a similar worry. I was afraid the fan wasn't kicking on because the temperature was fine while riding, but crept up at longer stop lights almost to the red. It turns out the switch is set to a very high temperature as far as the gauge reading is concerned; my fan doesn't turn on until the gauge reads 3/4 or 7/8, but as soon as the fan kicks on it dips down and everything is fine.



In summary, in my admittedly inexperienced opinion it's operating normally.



No reason not to completely check over the cooling system though, you definitely don't want any issues creeping up on you there. I would caution against opening the radiator once the engine is hot however. From my general automotive experience the cooling system is pressurized on many vehicles and you may only succeed in dousing the area in very hot coolant. "Burping" or "bleeding" the system is a good idea in general, just make sure you find out the proper procedure.
 

·
Registered
Joined
·
264 Posts
could be a bad gauge or power suplly problem. read this. My link
 

·
Registered
Joined
·
210 Posts
I just bought a 1983 CX650C about a week ago and had a similar worry. I was afraid the fan wasn't kicking on because the temperature was fine while riding, but crept up at longer stop lights almost to the red. It turns out the switch is set to a very high temperature as far as the gauge reading is concerned; my fan doesn't turn on until the gauge reads 3/4 or 7/8, but as soon as the fan kicks on it dips down and everything is fine.



In summary, in my admittedly inexperienced opinion it's operating normally.



No reason not to completely check over the cooling system though, you definitely don't want any issues creeping up on you there. I would caution against opening the radiator once the engine is hot however. From my general automotive experience the cooling system is pressurized on many vehicles and you may only succeed in dousing the area in very hot coolant. "Burping" or "bleeding" the system is a good idea in general, just make sure you find out the proper procedure.


The 500 that perrysburg has works differently than your 650. Our 500s have a fan thats driven all the time from the camshaft. Your 650 has an electric fan and will be thermostatically controlled..
 

·
Super Moderator
Joined
·
23,713 Posts
To burp the system I start the bike cold and add any coolant until the thermostat opens [they usually burp here] and then give it a few revs to check again.



Allow to cool and add any further needed coolant.



Some say to not fill the rad all the way but I do. It will find it's own level and while doing so it should push enough coolant through the recovery line to purge this of air.
 

·
Registered
Joined
·
1,265 Posts
As far as the voltage regulator--is that also called the voltage rectifier?


No, the one that regulates the voltage to the guage is a 7V Auxiliary Voltage regulator, usually located in the headlight



bucket. It is used to reduce power to 7 volts to the water temp guage.



The voltage regulator/rectifier is a finned silver part quite a bit larger and located by the battery, and the solenoid.



Good luck.
 

·
Registered
Joined
·
8 Posts
The 500 that perrysburg has works differently than your 650. Our 500s have a fan thats driven all the time from the camshaft. Your 650 has an electric fan and will be thermostatically controlled..


Ah, sorry; I thought that was based on the year, not the model. Still have lots to learn about these bikes!
 

·
Registered
Joined
·
210 Posts
Its all good man! I'm still learning with these old things too..
 

·
Registered
Joined
·
103 Posts
Discussion Starter · #16 ·
OK, I pulled the tank off today to replace the throttle cables and while doing so took the opportunity to check the radiator level. It was filled to the top. So I'm thinking 3 possible moves at this time:



1.) Check the 7v regulator. Where on the bike is the easiest place to access the electrical to check the voltage? And please give details on what I need to do including do I need to rev the engine?

2.) While I have the tank off maybe I should replace the thermostat?

3.) Should I drain the coolant and using a hose flush out the engine by disconnecting the radiator hoses?
 

·
Registered
Joined
·
1,364 Posts
OK, I pulled the tank off today to replace the throttle cables and while doing so took the opportunity to check the radiator level. It was filled to the top. So I'm thinking 3 possible moves at this time:



1.) Check the 7v regulator. Where on the bike is the easiest place to access the electrical to check the voltage? And please give details on what I need to do including do I need to rev the engine?

2.) While I have the tank off maybe I should replace the thermostat?

3.) Should I drain the coolant and using a hose flush out the engine by disconnecting the radiator hoses?
1) follow the wire from the temp sender at the thermostat housing to a bullet connector. Open the connector and check the voltage on the side of the connector NOT going to the sensor. It should be 7V +/-. Key ON.

2.) might not be a bad idea, but if it is working why mess with it. The thermostat is a common one from autos and available cheap from your local auto parts store. Search this forum for a good part number.

3.) That is one way, consider using a vinegar fill as a cleaner then re-flush and refill. Distilled water is best for the antifreeze dilution.



Search around the forum for lots of ideas and info on cooling system flushing and cleaning.
 

·
Registered
Joined
·
103 Posts
Discussion Starter · #18 ·
I found the post for the thermostat replacement part at a local parts place. Will I need to replace any gaskets once I open it up to replace the thermostat?



Do I simply drain the radiator, fill it with (white) vinegar and some sorta water mix? turn on the bike and let it bleed out the bottom hose and then repeat? What happens if I'm not quick enough and the radiator runs dry before I get a chance to repeat?



Sorry for all the detailed questions, I'm an IT guys not a mechanic.
 

·
Registered
Joined
·
8,423 Posts
I found the post for the thermostat replacement part at a local parts place. Will I need to replace any gaskets once I open it up to replace the thermostat?



Do I simply drain the radiator, fill it with (white) vinegar and some sorta water mix? turn on the bike and let it bleed out the bottom hose and then repeat? What happens if I'm not quick enough and the radiator runs dry before I get a chance to repeat?



Sorry for all the detailed questions, I'm an IT guys not a mechanic.


Don't apologise for relevant questions.That why myself and other contributors are here but your civility is duly note




For the coolant flush just drain the old coolant out.Put the drain plug back in.Pour a couple of bottles of white vinegar in.Top up with water.Run the engine up to working temperature(It will do no harm) and watch the coolant in the Radiator until it starts flowing with the Rad cap off or feel the coolant pipe at the side of the engine.It will become warm when the thermostat opens and the coolant flows around the system.You can hold the engine at say 2,000/3,000 rpm a few times to speed up the engine heat-up.



Leave the bike overnight and then drain the Vinegar mix out.Fill with clean water and repeat the above but you don't need to leave overnight as all you are doing is neutralizing the Acetic Acid(Vinegar).Once it's flowing again switch off and drain and leave the engine to cool.Then re-fill with the 50/50 mix of coolant.



Click here as well,



http://www.pdsrecording.site90.com/cxgl500/Coolant.htm









You may need a new thermostat O-ring when you take the top off but not usually.

Also note that there are two screws/bolts holding the top on and a Bracket which has a screw/bolt a total of 3 around there.This bracket is very important.You should clean it to bare metal where the bolt hole is and the bracket bit there so it has a good clean bare metal ground point as it grounds the Temp sender unit which is part of the assembly.



HTH
 

·
Registered
Joined
·
2,601 Posts
So if is 90 degrees outside and you have just come off the freeway, and now sit at idle for 10 minutes, I would say it is a "normal"condition under those circumstances.
Agreed. Even if it isn't a hot day and I haven't been on the freeway a really long light or traffic jam can easily push it to 3/4 or even a little more. That's one of the reasons I swapped to an electric fan and will have a variable speed controller out soon.



Other advantages:

1) Long lights won't bother it.

2) No chance of the stock fan exploding and taking the radiator with it.

3) Frees up at least 12 HP thus your mpg will improve.
 
1 - 20 of 23 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top