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Discussion Starter #1
Hi all,

Issue: CX500 idles with left cylinder firing intermittently at idle and dies if left idling. Right cylinder fires well and regularly.

I tried my best to aid all weakness of the CX motor (1979 Standard 23k all stock to start), here’s what I’ve done:

* Tightened cam chain: had rear engine cover off: tensioner had been the plenty of life left and replaced mechanical seal

* Set the hall plate again and again: made ignition adjustments repeatedly despite the lack of flywheel markers but timing seems good enough to run well - also made rough 2mm adjustments to magnetic rotor per Ray’s manual as well.

* Compression tested: 120+ PSI both sides

* PCV routed to fuel lines and breather filter per motofaction article. Seems to work well.

* Ignition components: replaced spark plug wires, coils compatible with 12v kit linked from Ray’s site, did brass rod mod, grounded ignition control unit to chassis, used recommend (by Ray via email) ignition curve.

* Switched carbs: used Murray’s carbs side to side to no affect. Carbs switched made absolutely no difference. Also cleaned both carbs throughly.

* Switched coils: Switched coils and wiring (meaning left sparks with right timing etc.) then coils with factory wiring with no major impact to idle. Left and right spark plug caps and wires were also switched.

* Adjusted idle speed: tightened/loosened idle screws to ensure that idle speed was not too low/high to run.

* Bought new spark plugs: Occam’s Razor - hoping the simplest issue is causing biggest problem. Also replaced the left spark plug wire and adjusted spring in left cap. No change.

My bike is obviously not stock, and that’s part of my issue. There aren’t many threads on this. Murray is very helpful, but I feel that my issue is no longer his responsibility... I feel guilty holding him hostage on the phone.

The bike ran GREAT with the full CDI system and CV carbs.

Please feel free to contribute any ideas, silly or not. I think I could possibly have a loose ground or wiring issue, although it’s strange that the issue is localized to the left cylinder.

Please help!
 

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You've done a lot of work, now you just need to isolate the problem. Swapping parts side to side seems to indicate more of a mechanical problem localized to that cylinder.

Have you checked valve adjustment? This will eliminate anything easy that might be out of spec... though, you would've noticed an excessively noisy valve train. A leak down test will also confirm proper sealing on that cylinder.

I know you have checked timing on that side, but specific verification of spark timing will go a long way towards identifying proper spark operation. Im not familiar with Rays setup, so you'll have to get with him on the specifics but you will want thi make sure that the actual firing event happens at the expected time with the proper duration and consistency.

An after thought occurred to me...a color tune kit might aid in "visualizing" an issue.


And...check for leaks, both vaccuum and exhaust.

That's all I got for now... hole it helps.
 

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I just took a quick look at Ray's manuals... a lot of good info there.

Definitely be able to diagnose any timing related issues...if I had to guess... I'd say that the pick up for the left side is gaining trouble...misadjusted or failing. Just a guess though.
 

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Discussion Starter #5
You've done a lot of work, now you just need to isolate the problem. Swapping parts side to side seems to indicate more of a mechanical problem localized to that cylinder.

Have you checked valve adjustment? This will eliminate anything easy that might be out of spec... though, you would've noticed an excessively noisy valve train. A leak down test will also confirm proper sealing on that cylinder.

I know you have checked timing on that side, but specific verification of spark timing will go a long way towards identifying proper spark operation. Im not familiar with Rays setup, so you'll have to get with him on the specifics but you will want thi make sure that the actual firing event happens at the expected time with the proper duration and consistency.

An after thought occurred to me...a color tune kit might aid in "visualizing" an issue.


And...check for leaks, both vaccuum and exhaust.

That's all I got for now... hole it helps.

Ah yes, I forgot to add that I checked and reset valve clearances within the last month. They should be within a thousandth of an inch, but I’ll put that on the list of things to check - in addition to doing a leak down test.

I’ll have to check into a color tune test; I’m not familiar with that procedure. I have reset ignition timing quite a few times, so while I’d like to think it’s a non-issue since the bike runs pretty well riding around the block, I’ll certainly give it another shot.

I’ve also sealed the exhaust using the OEM copper gaskets, and the exhaust is just the stock headers with 1ft resonators on it. I’ll have to double check vacuum!

Thank you very much for the input!
 

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Discussion Starter #7
I just took a quick look at Ray's manuals... a lot of good info there.

Definitely be able to diagnose any timing related issues...if I had to guess... I'd say that the pick up for the left side is gaining trouble...misadjusted or failing. Just a guess though.

Yes, I’ve ordered another pickup a few weeks ago so hopefully it will be arriving soon. The pickup was sealed with the resin Ray uses and it was a bit lopsided (about a quarter inch thicker on the left side than the right) so it cracked a bit when I installed it but there seemed to be no damage to the hall plate. Maybe the new plate will solve the issue... Thanks for the input!
 

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Discussion Starter #9
Had a hall plate fail on a friends bike. Ray replaced it.
Hmm. What did the failure entail? My unit still appears to function properly - all LEDs light up.
 

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Hmm. What did the failure entail? My unit still appears to function properly - all LEDs light up.
One side would not fire. I dont recall all the details but Ray's debug sheet confirmed the failure. Only helped with one install and the fail occurred after 100 miles or so
 

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Discussion Starter #11
One side would not fire. I dont recall all the details but Ray's debug sheet confirmed the failure. Only helped with one install and the fail occurred after 100 miles or so
Hm, ok. Mine still fires intermittently, but it’d be nice and easy if I could just swap the plate out!
 

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if i can make a suggestion if you have a timing light hook it up at night to the left cylinder
start the bike and pull the trigger see if the spark to that cylinder is steady or if its intermittent
i have also used these things IN-LINE Spark Plug Pick Up Coil Tester 6-12V Engine Ignition Diagnostic Tool HD | eBay

often you can see that its is or is not missing and it could be a signal issue so then ray would be able to help you
 

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Discussion Starter #13
if i can make a suggestion if you have a timing light hook it up at night to the left cylinder
start the bike and pull the trigger see if the spark to that cylinder is steady or if its intermittent
i have also used these things IN-LINE Spark Plug Pick Up Coil Tester 6-12V Engine Ignition Diagnostic Tool HD | eBay

often you can see that its is or is not missing and it could be a signal issue so then ray would be able to help you

Thanks for the advice. I have ordered one of the devices you linked, we’ll see if it helps me determine what’s wrong. I will say that it seems like the left cylinder fires at any RPM above idle, but I’ll see if I can make more specific observations on its behavior today.
 

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Discussion Starter #15

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Discussion Starter #16
UPDATE 06.08.2020:

Here is a video of the bike running

I also:

  • Checked valve clearances, within .001”
  • Swapped carbs again
  • Cleaned spark plugs again
  • Replaced spark plugs again
I am trying to locate a leak down test locally. I am waiting to receive my replacement hall plate from Ray. I have ordered a spark detection device per Murray’s suggestion.

As usual, bike runs strong on cold start and fires on both cylinders. Once choke is released, idle settles down and left cylinder begins dropping out. giving the bike throttle and holding at 6k or so results in pretty steady and healthy sounding operation, although I can’t really trust my ears at this point after hearing it run so poorly for so long.
 

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Discussion Starter #18
Being happy on choke gives a clue that this may actually be a fuel problem.

Haven't moved the low speed mixture screws at all?

Out is lean. If they've topped out on their springs they can then undo themselves.
I did try adjusting both ways, and I have swapped carbs as stated before with identical results, right cylinder behaves normally with either carb, left misbehaves with either carb.

I did try readjusting the mix screws and idle screws after reading your comment and it made no difference. Giving throttle to the bike brings it alive again, only to have the left cylinder die shortly after. I appreciate the idea, though!
 

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Discussion Starter #19
UPDATE:

Here is a video of the Rae San control unit and its behavior.

Notice how the right cylinder spark indicator is very regular, while the left spark indicator is erratic and unpredictable. To me, this is rather compelling evidence that there is either a loose connection between the control unit and the hall plate or that the hall plate has been compromised entirely. I will check the plate and connectors and post with an update.
 

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Discussion Starter #20
Ok all, sorry to spam my own thread, but I just removed the hall plate and verified good continuity in all leads coming off of the hall plate, which leads me to believe that the PCB within you the hall plate is compromised. As you can see in the video I’ve linked above, the left cylinder only receives signal sometimes while the right cylinder lights up regularly. The hall plate still illuminates at the right time on both sides, but it’s my belief that the signal is not being sent up to the control unit. I am inclined to think that this is an issue with the pickup itself due to the damage it sustained upon installation rather than the control unit which hasn’t been changed or otherwise damaged at all.

Here’s a photo album that shows how lopsided the pickup is in the resin. Take note of the thickness of the pickup from the right to left side. I’m not sure if this is by design, but the result was that the totality of the force was applied to the thin outside edge of the pickup causing the resin to break. I take responsibility for not being more gentle with the pickup, but the pickup was still able to be moved by hand when the bolt was flush to the edge of the pickup.


Like I said before, I do have a hall plate coming in the mail and it should be here in a week or so. Until then, I’m unmotivated to do any other tests on the bike... I’ve spent many hours and dollars diagnosing this issue, and unfortunately it seems that most of my headaches with the bike so far have stemmed from the new ignition.

I will be sure to update this thread if/when I resolve this issue.
 
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