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Technical Help Forum
Started by Gotfalls at 06-25-2008 8:50 PM. Topic has 55 replies.
  
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 06-25-2008, 8:50 PM
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Gotfalls
 
Joined on 04-02-2008
Vermillion, SD
Posts 110
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Alright, so both of my coils have cracks all the way along them. I know this could very well mean they're bad, but my bike has a lot of strange problems that don't seem to relate to something that the coils would effect.
I was driving today home from work. The bike always needs choke to start, which doesn't make much sense to me since it's been about 90 degrees here, so the engine has no good reason to be cold. When I started going, I noticed it sounded like it was backfiring a bit, which is one problem I started with. As I was driving the bike started riding worse and worse. I stopped several times and took off with no problem, but finally the bike died on me at a stop light. It started up again, needed some choke to run, of all things, but got me home. After this it was backfiring quite a bit and sounded like only one side was firing and was running very loud. I pulled in and it puttered off to death outside my garage. I parked it for about 3 hours, then went and started it. It ran low...with 3/4 choke it was still idling at 1500.
I'm starting to understand how the engine works, but when it comes to electrical issues, I have no clue whatsoever where to start.
I appreciate any help. Thank you for reading.
Forgot to mention that my butt was getting really hot on the ride home, a 10 minute drive. The temp guage isn't working.. Why would the bike be getting hot that fast? It's not leaking coolant...the radiator grille looks like it needs a good cleaning or replacement.
-1979 CX500 Custom - "Doc"
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06-26-2008, 5:23 AM
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Shep
Joined on 01-30-2007
Hull.East Yorkshire.England
Posts 2,121
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I'd get some better coils as you know they are weak.This may well cure your starting problems.The fact that you need to choke the bike to start could been because of a weak spark because of the coils?
A cooling system flush wouldn't harm.Use the search function with 50/50 white vinegar shep in it for info on this.Also replace the thermostat.Take the old one to an Auto parts shop and you can get a standard car one for under a 3rd of the price of a so called,"Honda" one.Same with the Rad cap.
New Global CX/GL Forum,
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06-26-2008, 10:19 AM
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lanispet
Joined on 10-10-2006
Meggett, SC
Posts 206
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i would definitely recommend replacing the coils, however, i do have one other suggestion...
The choke reduces airflow coming into the engine, which richens the mixture. If it's running better with the choke on, then your engine is normally getting too much air or too little fuel.
On older bikes, this condition is very often caused by a vacuum leak. On a CX/GL, the first place i'd look is the rubber boots connecting the carbs to the cylinder heads. If they have a bunch of cracks in them, or are visibly pulling away from either the carbs or the intake manifolds coming off the heads, you'll need to seal them to get the bike to run well. There are a number of ways to do this that have been discussed on the forums here.
If you've ever noticed the bike to be making something of a hissing sound, then it's pretty much guaranteed that a vacuum leak is at least part of your troubles.
Massively hacked-up '80 CX500C bobber/ratbike- "Doom Cookie"
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06-26-2008, 10:39 AM
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monki
Joined on 05-02-2008
Happy Valley, Utah
Posts 78
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 Shep wrote: | Also replace the thermostat.Take the old one to an Auto parts shop and you can get a standard car one for under a 3rd of the price of a so called,"Honda" one.Same with the Rad cap.
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I just replaced my thermostat... the 82 Honda Civic thermostat is compatible. I also managed to plug in my temp sensor while I was in there. It's a pretty easy fix... it'd have to be if I did it myself. The clymer manual says you have to take off the radiator and header pipes. That's a dirty lie. Just move the coils out of the way.
'82 GL500i (Grover)
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06-26-2008, 11:24 AM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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When I installed the carbs the last time, and every time I've put them in for that matter, I've had to pry off the boots, which means a lot of twisting. I noticed that the boots were looking like they were developing cracks, so I wrapped them in electrical tape. Now I'm talking about the front rubber connection to the cylinder heads. Would the rear rubbers cause issues like this? If so, I'll wrap them in the tape as well. I'm not sure why it would only do this on start though. After driving a bit, aka warming it up, it doesn't need to choke, normally. On that last ride I had to give it choke to get it home though.
-1979 CX500 Custom - "Doc"
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06-26-2008, 11:34 AM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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I'm hesitating to replace the temp guage, as I think that'll also mean replacing wires. I've got a couple of wires cut under my coils, and I think it's going to be a pain replacing them
Here's the link to a post I made concerning those wires. Also it has a picture of my cracked coil - 1 side. The other looks very similar.
Click Here
-1979 CX500 Custom - "Doc"
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06-26-2008, 11:52 AM
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Randall-in-Mpls
Joined on 07-06-2007
Minneapolis, MN
Posts 1,311
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The green wire (should have a red stripe, I think) cut off at the air dam is the reason your temp gauge isn't working.
It comes from the temperature sending unit in the thermostat housing. The one missing from the cloth insulator next to the the rubber tube (should be dark blue with a red stripe, IIRC) comes from the oil pressure sensor. Both should connect to matching wires under the seat.
R
'78 CX500 - The Black Maggot
CX500 Factory Service Manual
1978 CX500 Parts Manual
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06-26-2008, 4:13 PM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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Would 14 guage cable work for both of those? The green wire looks like it might be pretty small.
And would these being cut have anything to do with my bike getting hot as mentioned previously? Or is the cooling system mechanical, not electrical?
Thank you!
-1979 CX500 Custom - "Doc"
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07-06-2008, 12:18 PM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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So I messed around with my bike until it finally started working semi-properly. I bought a multimeter but haven't tested anything electrical yet. Where should I start and how exactly do I use the thing...what should I be looking for?
This doesn't make much sense, but it's true. I put on two new hose clamps on the rubbers connecting the carbs to the heads, intake manifolds?, and it ran exactly the same. I then piddled a bit, looking for anyplace that might have had some sort of air leak and couldn't figure out anything... Keep in mind I have no idea what I'm doing really, just learning and piddling. I then added some gas...no luck still. Then I put some sea foam in the gas and it ran perfectly. Just as well as it did before all of these problems. Then I turned it on today and it idled a little bit low, around 1k. It's probably a temporary fix, and I'm wondering what might be the cause and how I could fix this.
Any help is great appreciated. Thanks for looking.
-1979 CX500 Custom - "Doc"
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07-06-2008, 1:19 PM
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Shep
Joined on 01-30-2007
Hull.East Yorkshire.England
Posts 2,121
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1ct you can chck the chargning system.Set the meter to 20v dc and put across the battery and run the bike at idel.Both my Cx give around 14..2v at 1100 rpm.This is a good general test of the charging system.
another check is the stator,
http://www.elsham.pwp.blueyonder.co.uk/cx500/stator/
You can also check the continuity and grounding of the 3 Yellow wire bolck under the seat.These are the stator coils.There should be continuity between them all and none of them should read ground to the frame.
My tester has a continuity setting that beeps if there's a circuit.
New Global CX/GL Forum,
http://globalcxglvtwins.hostingdelivered.com/
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07-06-2008, 7:41 PM
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Ayal
Joined on 05-19-2008
Massachusetts
Posts 89
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The Haynes manual recommends an ignition test in which you remove the spark plucs, look thm over for fault, fit them into their connectors, lay them on the cylinder head and ensure good electric contact. (I actually hrld them in place with elec tape to forestall any vibrations). Many warnings about not holding these by hane in danger of shock... Turn kill switch to 'on', leave gas valve off... hit the starter shortly. Should see fat blue sparks.
New spark plugs are cheap and easy to relace, if you did not already.
As for the multimeter, I'd set it to 20 volts as Shep said, tape it to the gas tank, and watch it while riding because charging is done by different coil portions at different devs and also motor temperature may play a role. Good luck.
Ayal
Strive to learn something new every day
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07-07-2008, 7:58 AM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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I tried doing this yesterday and found that my multimeter has no 20v setting. It may help to know that it's analog. It has 10 50 250 and 500 I believe.
Yesterday I took my bike out for a ride down the highway and had problems. It got up to about 70, then started acting funny, got loud, gave me a few surges, and killed. I hit the starter and it started back up as I was going, in fifth gear, but only ran on one cylinder. I drove it back home at its max comfort speed of 45. If I asked it to go faster, it just grumbled at me.. When going up hills that max speed was lower, down it was higher. When I got back to town, I had to sit and think for a minute if I wanted to go into a makeshift road or turn around and take another road home. As I sat, it idled at 1k on the 1 cylinder. When I turned it around and gave it gas, both cylinders were firing again and it got me home just fine. Outside the garage it idled at 1100ish.
Does this help to guide me at all?
-1979 CX500 Custom - "Doc"
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07-07-2008, 8:10 PM
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Ayal
Joined on 05-19-2008
Massachusetts
Posts 89
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This is beyond the knowledge I have acquired so far in my first season of riding/tweaking.
Do you think dirty air filter or dirty gas filter can be restricting high fuel mix flow?
I hope you get one of the experts to get involved here.
Strive to learn something new every day
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07-07-2008, 10:45 PM
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Anonymous
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a little history on the bike would help. did it work fine and then all of a sudden start working bad? did it sit for an extended peroid of time?it sounds like dirt in the carbs.
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07-07-2008, 11:07 PM
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Anonymous
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Not thats its of utter importance or anything
as the cables can all be say., black or red as long as they are connected properly
but the temp sender wire is usually green/blue
( a cut off fragmant can be seen in the above pic.btw).
The blue/red wire is the oil pressure sender wire
Reg
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07-08-2008, 6:08 AM
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Graywolfs02
Joined on 09-08-2007
Coon Rapids Minnesota
Posts 230
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| Gotfalls wrote: | I tried doing this yesterday and found that my multimeter has no 20v setting. It may help to know that it's analog. It has 10 50 250 and 500 I believe.
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Hi Gotfalls
Here is a bit of "Meter reading 101"
Below is my trusty analog meter from Radio Shack. Its been with me for many years and works well.
Your meter face may look different, but the operating of it will be the same.
On my meter you'll see 4 scales. One green, one red, and two black.
I will be talking about the 1st black scale with the 5, 10, 25 and 125 markings.
Below is the selector switch on the meter.
The switch has a number of selections, but for now I will be talking about the area marked as "DCV" (DC Voltage)
On the selector switch DCV has these choices: 5, 25, 125 plus 500&1K. For use with the bike, we'll only look @ the 5 to 125 range.
As you've probably guessed the 5, 25 and 125 corrospond with the same markings on the meter face.
Setting the switch to "5" you look at the marking using the "5" as the upper end reading, which in this case you would read a maximum of 5 volts.
setting it to 25 you look at the scale and now you read the upper end as 25 volts and so on.
When setting the meter range, if you are not sure of how much voltage you'll be looking at, ALWAYS set your meter to the larges setting and work down from there. Trying to read a large voltage ( say 50 volts on the 5 volt scale) can damage the meter.
This pic shows trying to read a 9 volt battery on the 5 volt scale. The meter needle goes all the way to the right ( known as "full scale deflection")
To properly read the voltage of the 9 volt battery I've set the selector to the 25 scale.
In the pic above the needle is now between the 5 and the 10 on the "25" scale. On this scale, each mark is read as .5 (half) volt. So in this pic, the battery voltage is showing 7.5 to 8 volts
So to be able to check the voltage at the battery using your meter, set it on the "50" setting and then read the scale that has "50" as the highest reading.
If you have any questions, or if I have just completely confused you, email me using the button below and I'll try to answer any of your questions.
Greg
1978 CX 500
Minnesota
Ride Safe, Ride Fast, Ride Far
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07-08-2008, 6:09 AM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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I bought the bike in April. The PO said he replaced the battery, spark plugs, and gave the carbs a good cleaning. The bike pretty much stopped working at the end of April, so I took out the carbs and cleaned and rebuilt them. I also installed an inline filter on the gas line.
The bike was running fine before all of this started happening. I was on my way home from work one day and the engine quit on me at a light. It needed choke to start back up and ran on only one side the 3 minutes it took to get home, then quit when I made it. It sat for a couple of weeks, as I haven't had the time to mess with things. I replaced the hose clamps on what I think are the intake manifolds (the rubber/metal boots connecting the heads and the carbs). It still puttered to near death until I poured in a couple ounces of Sea Foam. It then ran great for the day, but did the single cylinder problem the next day as I mentioned earlier.
This may be an easy problem to figure out for someone who has experience doing this sort of work, but this bike is the first engine I've worked on, and don't know anyone around here who works on their own bike. I appreciate all your help. Thank you.
-1979 CX500 Custom - "Doc"
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07-08-2008, 7:52 AM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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That was a huge help Greg, thank you very much!
I checked my battery with the bike off and it read ~11. I then checked it with the bike on and it bumped up to ~12ish, maybe 12.5.
Next will be the stator. I'll read over that site and get on it.
Again, thank you for your time and help!
-1979 CX500 Custom - "Doc"
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07-08-2008, 8:20 AM
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Graywolfs02
Joined on 09-08-2007
Coon Rapids Minnesota
Posts 230
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Glad to have been a help 
When you go to check the stator, use the "Ohms" section on your meter. You'll be using it as a continuity checker and not so much as looking for the resistance of the stator.
Do this with the engine shut off .
Connect the meter leads to any two of the lugs in the connector (has three yellow wire, found under the seat) and watch for that "full scale deflection" I mentioned in the previous post.
If you have the full deflection that is good, shows that the wires in and to the stator are good.
Now connect one lead to anyone of the lugs in the connector and connect the other lead to any metal part on the bike ( frame, engine block, etc).
If you have NO needle movement or deflection that is good!! 
However, if you do show needle movement that is BAD !! 
Showing a reading from the connector to "ground" means that the stator has gone bad and is no longer charging....which means engine out R/R.
Let us know what you find...if it is the worst case, many here (me included) can give you guidance on the R&R of the stator.
Greg
1978 CX 500
Minnesota
Ride Safe, Ride Fast, Ride Far
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07-08-2008, 1:35 PM
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Shep
Joined on 01-30-2007
Hull.East Yorkshire.England
Posts 2,121
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| Gotfalls wrote: | That was a huge help Greg, thank you very much!
I checked my battery with the bike off and it read ~11. I then checked it with the bike on and it bumped up to ~12ish, maybe 12.5.
Next will be the stator. I'll read over that site and get on it.
Again, thank you for your time and help!
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As previously stated if below 13.5v @ idle there is a fault with the charging system.both my CXs are at around 14.2v at 1100 rpm.
New Global CX/GL Forum,
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07-09-2008, 12:53 PM
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Gotfalls
Joined on 04-02-2008
Vermillion, SD
Posts 110
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