Honda CX 500 Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
60 Posts
Discussion Starter · #1 ·
Hello! I just happily upgraded to Murray's Carbs and finished the install this morning.
When revving there was some sputtering (even stalled) around 5000k rpms, I read to check the plugs and potentially do the brass rod mod. Once I figured out what the heck that was and where the instructions were, I found this. yikes! Lots of corrosion dropped out when these came out.

I'm happy to buy new spark caps if someone could drop a link to some that will work.
My alternative is to drill out the old aluminum rods as they are STUCK in the stock caps.
Thoughts?

Household hardware Auto part Metal Wood Art
 

·
Super Moderator
Joined
·
5,340 Posts

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,743 Posts
I think I'd try removing the rubber boot and sharply rapping the open end on something before I tried drilling into the aluminum.
If/when you do get it apart scrub everything with a Scotchbrite pad sprayed with contact cleaner to remove the corrosion (real contact cleaner, not WD40). I like to clean the contact in the bottom of the hole by shoving a small piece of the pad in, spraying in some contact cleaner and using a small slot screwdriver to turn the pad (I usually have to pull the pad out with a straightened paper clip with a tiny hook bent into the end).

I don't usually recommend replacing the resistors with brass rod if they are intact but at least one of yours is coming apart so it is probably a good idea for you. If you know anyone who welds ask them for the end of a brass welding rod (you want enough to cut 2 pieces the length of a resistor plus an aluminum rod. if it is flux coated remove the flux and scrub it with the contact cleaner to remove any traces.

With no resistor in the cap you should make sure you have resistor spark plugs. The resistors not only reduce radio interference but also affect the shape of the spark event's waveform.
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #5 ·
Thanks Bob!! I'll definitely give that a shot. I did get some brass rods from Murray with my carb kit.
I even thought about a long nail with some super glue on the head, putting it down in there to maybe adhere to the aluminum rod, then using plyers to pull it out?

Getting it out might be a pain but i'd like to stick to the factory caps with the boot around the top. The after market ones don't seem to have that.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
11,456 Posts
Getting it out might be a pain but i'd like to stick to the factory caps with the boot around the top. The after market ones don't seem to have that.
You can move the rubber hoods to the replacement caps.
 
  • Like
Reactions: drav77

·
Registered
Joined
·
1,479 Posts

·
Registered
Joined
·
60 Posts
Discussion Starter · #8 ·
Has anyone had experience with both the listed above? Quite a bid of price difference and would like to hear from anyone whos tried them, thanks.
I just ordered the cheaper ones and am going to move the stock rubber hoods on to them. If no one responds i'll let you know how it goes!
 

·
Super Moderator
Joined
·
23,405 Posts
Has anyone had experience with both the listed above? Quite a bid of price difference and would like to hear from anyone whos tried them, thanks.
I've used both but mainly the aftermarket - which don't have resisters so you need a resister plug with them. I use NGK DR8EA or you can use the DR8EIX irridium.
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #10 ·
I've used both but mainly the aftermarket - which don't have resisters so you need a resister plug with them. I use NGK DR8EA or you can use the DR8EIX irridium.
Can the brass rods be used on the aftermarket instead to replace the fuse?
 

·
Super Moderator
Joined
·
23,405 Posts
There's no need. The aftermarket contain no 'fuse' {actually a 5,000 ohm resister} and do not come apart like the OEM.
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #12 ·
I could have misunderstood the point of the Brass Rod mod with Murray's carbs, but thought the point was to not have the resister and get a hotter spark? or is that not right?
 

·
Super Moderator
Joined
·
23,405 Posts
Probably. I see it as removing a point of failure though.

The brass rod id used to simply replace the resister.

As the aftermarket caps contain no resister this becomes a moot point as the aftermarket resisterless cap is equivalent to an OEM resister with the brass rod mod.

Either way, both should have zero resistance.

The brass rod mod removes the resister which is a point of failure but does not address issues with the bakelite body breaking down and leaking sparks or the right angle strap inside the cap being broken or burned out.
 

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,743 Posts
There was a long discussion about this on the forum some time ago. I can't remember the details but apparently having some resistance between the coil and the spark gap has a beneficial effect on the spark pulse waveform. I think it has to do with extending the duration of the spark.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
11,456 Posts
I'm using the aftermarket plug caps from DSS, with "R" plugs. No issues in close to a decade.
 
  • Like
Reactions: D-Fresh

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,743 Posts
Hello! I just happily upgraded to Murray's Carbs and finished the install this morning.
When revving there was some sputtering (even stalled) around 5000k rpms, I read to check the plugs and potentially do the brass rod mod. Once I figured out what the heck that was and where the instructions were, I found this. yikes! Lots of corrosion dropped out when these came out.

I'm happy to buy new spark caps if someone could drop a link to some that will work.
My alternative is to drill out the old aluminum rods as they are STUCK in the stock caps.
Thoughts?
I want to thank you for posting this when you did. Eccles (the CX650E/GL500 based sidecar outfit I drive in the winter) has been getting hard to start and the left cylinder has been cutting out intermittently. At first I thought it was due to stale fuel (a tank of gas lasts me way too long these days) and it did feel a bit better after I filled the tank last week but it didn't fix the problem.
I was starting to think it felt a bit like it did when a pulse generator failed a few years ago.
Then you asked about this. And I started thinking about it. Yesterday I unscrewed the connector (that's what NGK calls the part that clips onto the plug) from my left cap and everything inside it was pretty oxidized and the end of the connector that the resistor is supposed to press against had a depression burned into it.

The right cap looked OK but I figure it is best if they are both the same so I cleaned out both of them the way I described in post #4 and used the resistors, springs and connectors from a different set of caps I had laying around (these parts are used in a lot of NGK caps) to rebuild them.

When everything was back together I touched the Start button and it fired immediately. When I went out this afternoon it started more easily than it has in a long time and felt much happier than before so I gave it a bit of a run and it didn't cut out under any conditions.
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #17 ·
I want to thank you for posting this when you did. Eccles (the CX650E/GL500 based sidecar outfit I drive in the winter) has been getting hard to start and the left cylinder has been cutting out intermittently. At first I thought it was due to stale fuel (a tank of gas lasts me way too long these days) and it did feel a bit better after I filled the tank last week but it didn't fix the problem.
I was starting to think it felt a bit like it did when a pulse generator failed a few years ago.
Then you asked about this. And I started thinking about it. Yesterday I unscrewed the connector (that's what NGK calls the part that clips onto the plug) from my left cap and everything inside it was pretty oxidized and the end of the connector that the resistor is supposed to press against had a depression burned into it.

The right cap looked OK but I figure it is best if they are both the same so I cleaned out both of them the way I described in post #4 and used the resistors, springs and connectors from a different set of caps I had laying around (these parts are used in a lot of NGK caps) to rebuild them.

When everything was back together I touched the Start button and it fired immediately. When I went out this afternoon it started more easily than it has in a long time and felt much happier than before so I gave it a bit of a run and it didn't cut out under any conditions.
Great news, glad to hear Bob!!

As a follow up I got mine out on the road yesterday. Definitely not an issue. It's running great!
Murray's Carbs are bad a** - Now to pick up his throttle tube to take out some of the slack.
 

·
Registered
Joined
·
860 Posts
I one time diligently cleaned a half a dozen or so of these caps, testing each element with an ohmmeter. The loose pieces would test find and still some caps would not function properly. I finally cut a failing cap open and found this rust which might have been the problem:
Wood Door Gas Household hardware Circle

As part of the process I'd stick a probe like a pick or something down into the cap and take my ohm reading. I could get a good reading this way but when I reassembled the cap he readings were intermittent or nothing at all. I figure the problem could be where the spring meets the rusty area or where the cap makes its bend:
Line Font Wood Auto part Metal

This was when I first got the bike some 10 years ago. I remember pulling the carbs a couple of times among other things trying to remedy the problem. Over the years the best money I spent on the bike was for new caps, coils and wires.
 

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,743 Posts
The corrosion in that contact inside the cap is why I shove a piece of Scotchbrite in, spray with contact cleaner and use a screwdriver to scrub the corrosion out. After pulling the Scotchbrite out I sprayed more contact cleaner in and let it run out, then blew compressed air into the cap. When I looked in with a flashlight after I could see the shiny contact at the bottom of the hole.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
11,456 Posts
I recall soaking caps in white vinegar trying to get them clean. Results were mixed, but mostly poor. I ended up getting aftermarket replacements.
 
1 - 20 of 25 Posts
Top