Honda CX 500 Forum banner
1 - 20 of 39 Posts

·
Registered
Joined
·
46 Posts
Discussion Starter · #1 ·
Just got my first bike last week, 79 cx500 Custom. Having problem with overheating, come close (and today actually hit) red one temp guage after about 10 miles of city driving, limited stop and start, quite sure it is overheating and not a false reading as I feels very hot and I could smell a strong sent of antifreeze. I am really new to motorcycles and have limited car engine repair experience. I have run a flush agent through and refilled with 50/50 coolant / distilled water mix. I have read several forums but can't get past the real basics. Issues of, what is this deal about making sure not air is in system and where to get info on how to change thermostat. My common sense is good but experience is minimum. Open to any advise is your are willing to work with this very old, new guy. thanks
 

·
Registered
Joined
·
1,164 Posts
Just got my first bike last week, 79 cx500 Custom. Having problem with overheating, come close (and today actually hit) red one temp guage after about 10 miles of city driving, limited stop and start, quite sure it is overheating and not a false reading as I feels very hot and I could smell a strong sent of antifreeze. I am really new to motorcycles and have limited car engine repair experience. I have run a flush agent through and refilled with 50/50 coolant / distilled water mix. I have read several forums but can't get past the real basics. Issues of, what is this deal about making sure not air is in system and where to get info on how to change thermostat. My common sense is good but experience is minimum. Open to any advise is your are willing to work with this very old, new guy. thanks
Couple quick suggestions, put your location in your profile info, because you might live next door to me, and I might be able to come help, also, put your bike year, make , model in your signature line so when you ask for help, I can find any post you've had, and know what you ride... After filling back up with antifreeze, did you run the bike until it warms up and fill it again? After the thermostat opens up, which is after it reaches normal running temperature, the water will get to run through the motor and not be stuck in the radiator, so what I'd do is take the cap off the radiator, run the bike for at least 10 minutes, get it to where it's good and warm, and see if the water level is low. The other thing is that these bikes don't like to sit still too long, the fan is connected to the camshaft, meaning fan speed is relevant to engine speed. Some people have done electric fan conversions so the fan runs whenever it needs to, rather than when the engines revving high enough. If you're smelling antifreeze, then it's coming out somewhere, you may have a leak... After checking the coolant level, I'd take the bike out on the highway or somewhere that isn't stop and go, so that the bike isn't sitting and just idling, which is spinning the fan slowly. With my bike when it's good and hot outside, and I'm running at high rpms, doing about 80+ mph down the highway for long periods of time, over an hour, it gets warmer than I like, but I don't think it's ever hit the redline...
 

·
Registered
Joined
·
967 Posts
I have the inlaws over now, but will post some of the stuff I did to flush and clean my system in about an hour or two! Welcome!



Here is a thread that has a bit of information on the coolant system, and some of the things I did to flush mine. Not saying your bike is overheating because of a mineralized system, but this has some good pictures in it of where the thermostat is located, some of the coolant system components etc.



http://cx500forum.com/index.php?/to...lush/page__p__43182__fromsearch__1#entry43182
 

·
Registered
Joined
·
1,354 Posts
Check that the return pipe is hot when the gauge is at center or above, that indicates the thermostat is opening. Check voltage in the wire going to the sending unit. It should be 7V +/-. If the voltage is OK then the temp is probably up. If The pipe is not hot the t-stat

is stuck and needs replaced (assuming you already have coolant and purged air).

Download the service manual for details on servicing the cooling system.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #5 ·
I hope this is the right place to thanks to all of you who replied. I have since updated my profile with my bike 1979 CX500 Custom and I live in Cleveland very close to Edgewater Park on the near westside. I will review the manual I've downloaded and warm the bike up with the radiator cap off. I flushed the system, filled the radiator with 50/50 but that was it. I saw the overflow reservoir had fluid so I "assumed" all was fine. I will check that out again via the radiator cap plus take the other suggestions.
 

·
Registered
Joined
·
967 Posts
I will check that out again via the radiator cap plus take the other suggestions.


This is the only way to confirm you have proper fluid level in the radiator. You're not too far from me, maybe 25 to 30 minutes. I would try to check out the thermostat,...even take it out and clean it.



Just a thought, but if the thermostat is stuck shut, you may think you have flushed the system, but if coolant & flush is not circulating the flush will be minimal. It only takes about a half an hour to 45 minutes to remove and replace the thermostat...maybe an hour and a half to clean and reinstall. All of the orings are available at the Honda Dealer. I purchased the Orings for the thermostat, and the other Hard Piping that connects to the Sender Housing, as well as the return pipe that runs horizontally on the left/shift side.



Hope you got to see the pics I posted of the way I flushed my system...worked AWESOMELY.
 

·
Registered
Joined
·
2,601 Posts
Don't forget that the thermostat for a 1980 Hinda Civic is the same thing for 1/3 the price.
 

·
Registered
Joined
·
8,423 Posts
That I didn't know


The rad caps are car ones as well which you can get cheap from Autozone type shops.I never pay a premium price for these things.There was recently a so called,"Honda" new rad cap on UK Ebay asking 25 beer tokens!!!!
 

·
Registered
Joined
·
117 Posts
Hey 1st bike if you are still having problems as rick was saying about how close to him you are im about 4-6 streets away from rick also. If you need a hand let me know as well, I had that same problem but turned out to just be my 7 volt resistor for the temp gage. Keep us updated on the problem, and any others you might have. Oh, also welcome to the boards and the cx fun life.
 

·
Registered
Joined
·
2,601 Posts
Same thing with the oil drain plug and who knows what else fits both their cars and bikes?



I had to buy a new oil drain bolt & washer as the PO must have used vise grips on it several times.

Ordered from TAS and the p/n's on the Honda bags matched the ones used for many of their cars.
 

·
Registered
Joined
·
1,164 Posts
If you find it is the voltage regulator, I have a couple of them lying around I'd sell rather cheap
 

·
Registered
Joined
·
458 Posts
Your rad may be blocked inside. Even a heavy duty flush wont clean it. Back flushing etc, wont do it either. Your rad will need "professional help", like strip down and clean all the core tubes, and re-solder together. After 30 years, its unknown condition, and any variety of tap water/dam water/creek, river, puddle etc etc....has been used to top it up.



Worst case scenario, of course. Probably air in the system, as stated.



Also make sure you actually have a thermostat. Running without one "may" cause overheating, as the water flows too quickly through the rad to cool it down. If the temperatures in your town don't vary a lot, you can cut the spring etc. out of the thermostat, and put the brass "plate" back in. It should slow flow enough. Just a hint, if you're on the side of the road......




Let us know how you get on.
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #15 ·
Thanks again, still not doing so good with my overheating problem, maybe worse.Here is the latest. I ran running the bike well into the right side of the temp gauge with the radiator cap off to see if there was movement in the fluid in the radiator once the bike warmed up. It was plenty warm "and nothing but a few ripples from vibration". I drained the system and removed the thermostat housing, and "NO THERMOSTAT". I installed a new 1980 Honda Civic thermostat (fit perfect) carfully put it back together, filled the system with 50/50 antifreeze/distilled water and ran the bike again with the radiator cap off. Still nothing AND this time the bike took a little longer to heat up (may just have been sitting longer between starts that before) but it seemed to run even hotter than when I ran it before when it had no thermostat. I did not take the bike out and do realize it will get hotter, quicker at low revs and not moving but since there was no movement of fluid in the radiator even with a new thermostat I figured my problem was not because of the slow fan and no air. My uneducated fear is the water pump is shot and again my guess is that is a big deal. Please advise. Also, anyone every try making decals on an inkjet printer to use on your bike? My bike has a fairing, Windjammer (I think), would that have been an option or add on or what? My bike is a 1979 cx500 custom, anyone know what color options were available for my bike in 79 and know a source of pics.
 

·
Registered
Joined
·
8,423 Posts

·
Registered
Joined
·
967 Posts
Hey 1st bike if you are still having problems as rick was saying about how close to him you are im about 4-6 streets away from rick also. If you need a hand let me know as well, I had that same problem but turned out to just be my 7 volt resistor for the temp gage. Keep us updated on the problem, and any others you might have. Oh, also welcome to the boards and the cx fun life.


+1 1stbike...PM either me or Jon, maybe we can drop by and give you a hand...three heads might be better than one!!
 

·
Registered
Joined
·
46 Posts
Discussion Starter · #18 ·
+1 1stbike...PM either me or Jon, maybe we can drop by and give you a hand...three heads might be better than one!!


Question- At idle (give or take a few rpm) how long should it take for the thermostat to open up (with the radiator cap off) and I should be able to see fluid begin to move in the radiator? Question 2 If a bike is truly overheating , red on the guage, are there any symptoms I should have when I shut the bike off?(I road the bike tonight (with vinegar as the only coolant) and from a cold start I hit the red (on the guage) in 1.4 miles.) I pulled over, shut off the bike and waited for the guage to go down, the return pipe was warm and the engine (in my uneducated and inexperience opinion) seemed pretty normal dispite the red on the guage). I have got the 7V at the sending unit but the radiator return pipe is just warm even when the guage hits the red. I do not see any movement of fluid in the radiator when the guage is about 5/8 and climbing. Either the water pump is not doing its thing or the impeller could be loose (I am told) OR I am not waiting long enought for the thermostat to open when viewing the fluid with the radiator cap off.

Can anyone tell me where the voltage regulatior is I would like to make the one outline in this forum but not sure where the new one goes.
 

·
Registered
Joined
·
458 Posts
Hmmm, sounds like dicky gauge. If the engine were truly in the red, the rad would spew boiling water out, and you wouldn't be able to hold the return pipe. It is possible the water pump has fallen part, however, the water would boil.



Any one ???
 

·
Registered
Joined
·
103 Posts
I had a similar concern and no mechanical experience so when I told to watch for fluid flowing at 180F (beginning of thicker line on temp gauge) I wondered how I would tell a difference with the water vibrating from the engine running. Well you can't miss it if your bike is working correctly. There is a distinct flow of water from left to right if you are facing from a riders position on the bike. Like I said I have no mechanical experience but what little I do have from the aforementioned--it sounds like you have a bad water pump or blockage. Did the coolant flow without the new thermostat? Or did you not know to check when you started this process? Without a thermostat it should have been flowing once you started the bike.
 
1 - 20 of 39 Posts
Top