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Discussion Starter #1
G'day all, first time post.

Understanding that this topic is well covered, I have managed to (as a new rider/mechanic in general) narrow down the symptoms which have niggled away at me since I bought the bike a month ago. So, I've reached a point where the issue seems to be only the left carb, but was unable to solve the problem by simply adjusting the pilot screw, which looked to be at a different adjustment to the right carb.

Longshort: I don't know much about carbs, but the left seems to be running super rich, no matter how much I play the pilot screw. It still sparks when given revs, but left to idle on its own (without the right spark lead connected), will flog out immediately. This is not the same case as the right carb, which seems to isolated idle fine.

Backstory: I picked up the bike and planned to drive it ~500km home after having being garaged most of its life. The bike only had 17,000km on the odo, so was expecting a few signs of ageing; and original parts, well, pretty much everywhere. After replacing all the oils, coolant, checking over the sparkplugs, replacing in-line fuel filter and other minor bits of maintenance, I set off. The first 150km was fine, no odd knockings or anything out of the ordinary. It was only when I passed through an exceptionally foggy gorge followed by appreciable rain did I come across my first hurdle.

The issue at the time seemed odd. The bike was fully warm having had a long ride without any apparent problems. I would be riding, and regardless of gear/speed/revs/throttle, the engine would start flogging (not igniting), even after trying to kick it back into life by down changing as I pulled over. Sometimes I was successful and the bike kicked back into life and I would find myself accelerating to try to fix whatever was happening. Once I had exhausted all the gearing, the bike would then cut out completely. I stood in the pissing rain trying to diagnose the problem. The temp gauge was fine, no oil light, so I choke started and limped to the nearest gas station so I could have a proper rummage around. The problem didn't plague me for that 15km stretch, but come to think of it the rain had subsided. I had limited tools and so checked the spark casings again - no water. I was convinced that something was going on with the intake system so pulled the seat off to check the airbox. Air filter looked reasonably clean and free of moisture, but the box itself and the grill (localised over the crankcase breather entry) had some condensation. So I tried to sponge it out and left it in my mates garage to dry out overnight. Hopped back on in the morning and rode 5 hours home. Felt like I had a few intermittent surges of power at the same throttle through some of the wetter ranges, but wasn't sure if it was just me being bounced around by the suspension. Other than that, no cut-outs! Thought the problem had been solved until it started raining again, and there I was pushing my bike out of another intersection. It was only at this point I became super critical of the frequency of backfiring going on from what I thought were some 'characterising' Harley mufflers, and I tried opening the choke a little whilst riding which seemed to keep the bike alive too.

Finally, this leads me back to the start of my post. The isolation test makes me think that it isn't an ignition fault, and the change in humidity/air mix into the fuel delivery points toward the carb, especially the left hand side. It might be seals/boots, but I doubt what has been replaced on one side hasn't been done to the other. As it stands, I have had the bike running in isolation on the left cylinder, turning it off/on to try different pilot screw settings, none of which seem to solve the problem, even when its dry. I think I will eventually do a complete (Keihin) carb overhaul, but will have to buy from America along with a tuner of sorts as I will be putting some pod filters on with the upgrade. Point being, I don't want to pull the carbs out on a weekend to figure out they need major works with the parts a few weeks away.

Any thoughts of further diagnosis and/or cleaning methods that might fix the problem without me taking the bike off the road for a rejet? :vs_shrug:
Thanks in advance!
 

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I'm thinking along the same lines as Murray. The one & only time I had to have mine towed home it felt like it was running out of fuel. I replaced the fuel in the tank, had a go inside the carbs and even replaced the petcock. It was OK for a couple of weeks but when it did it again the next time it rained I figured out that it was a combination of water dripping off of the left side of the fairing onto the spark plug cap and the boot on the cap not sealing well on the plug.
 

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BTW GLide, this isn't really your first post. That was back on May 31st. Now, it may be your first thread, just so you know the distinctions.

Moisture and electrics have a great ability to hide themselves in masks of other symptoms. Perhaps there are issues with the coils and or coil wires to the plugs? Minute cracks or frayed wires can allow moisture in and cause seemingly random faults.
If you are planning to keep and refurbish the stock carbs, definitely get Larry's book, linked below. Maybe some of the other down under guys can assist you with part supplies etc.
 

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I think both of you are on the right track.

Just go thru the ignition clean coil mounts connections.

ohm test wires and bring the whole high tension side up

to snuff .

Do your high mileage maintenance don't "skip" anything.
 

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One more thing: How old are your spark plug wires (if you don't know assume that they are the originals and are 35 years old. Over time & with exposure to light & air, rubber deteriorates. After 35 years even the best silicone rubber spark plug wire insulation will be well past it's prime. Tiny cracks in the insulation that you can't see will let in water & you may find your ignition shorted when it rains. When this happened to my '77 GL1000 in the early '90s I wasn't surprised because the wires were old. Your wires are probably well over twice that age now. Limping home in the rain on 1 cylinder isn't much fun.
 

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Discussion Starter #7
Had cleaned out the well and spark drain-hole but after having another look it seems to be full of oil again - thanks for the reminder! Swapped plugs over (understandably not the best test), but still getting the same discrepancy (RHS runs fine on other sparkplug).
 

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Discussion Starter #8
Heh you got me! Haven't joined a forum worth contributing to ;) so catching up on the lingo. After my findings going back to the bike again today, I suspect you might be right. There is a minute cracking in the spark lead just after the junction to the coil. Will definitely be seeing Larry sooner or later! Thanks for the 10cents, I've seen you post this to other people with the same problem, just had my blinders on.
 

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Discussion Starter #9
Cool! Next on the list. I'm assuming its my lack of knowledge in why I can't quite understand the 'high tension side up to snuff', so will have a read around to save you repeating yourself.
 

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there are quite a few NZ cx owners on here and on the Australian CX/GL Forum. Theres also a CX Facebook page if you are so inclined.

I would suggest doing the brass rod mod to your plug caps as soon as possible too.....

Econohonda in the Waikato has many parts for older bikes , and Malcolm is a CX fan from way back. Try him before you spent your hard earned cash overseas.
 

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Discussion Starter #11
Got that right! On the hunt for some replacements as we speak. Already bitten off more than I can chew.
 

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Discussion Starter #12
Cheers! Will do some more research and check out those breadcrumbs, thanks for the pointers.
 

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Had cleaned out the well and spark drain-hole but after having another look it seems to be full of oil again - thanks for the reminder! Swapped plugs over (understandably not the best test), but still getting the same discrepancy (RHS runs fine on other sparkplug).
Oil????? There should never be oil in the spark plug well. The only way that can happen is if the rubber piece that seals the inner part of the rocker cover is missing or displaced.


The hole in the red circle in this pic is the drain hole. If it is blocked by debris or even intentionally (I remember someone posting about a bike that had bolts in those holes) any water that gets into the spark plug well can't get out.


Have a look at the page where those pics came from https://motofaction.org/motorcycles...0-cx650-gl650-oil-leaking-out-hole-side-head/

BTW: You are new to forums so you probably haven't yet realized that whenever you reply to a thread your reply appears at the end of the thread, not immediately after the post you are replying to. It is better to put all of the replies in one post and mention what each part of the post is replying to.
 

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Discussion Starter #14
Hey all, I'm back after soaking up your sound advice. Understand the pulse has run cold on this thread (moved out of town for a job which separated me from the old girl) - but just in case there's anyone still following..

Pulled the carbs off and found that the LHS inlet manifold was hairline fractured at the piston mate (confirmed drop from the seller). The LHS spark plug cap too was cracked about the base grommet. So, I hopped on DavidSilver and got busy shipping a set of aftermarket spark plug caps, inlet manifolds, and other superficial bits. As I'm writing this it's sounding like the fall might not have been as "driveway" spec. as described. Confirmation bias is strong with this one.

Replaced the lot: quick spray clean of the carb whist it was out - didn't have time to go further but found the choke spring attaching the RHS butterfly valve had popped off. Everything else looked clean as a whistle, although not quite sure what I'm looking at regards needle. Replaced the spark plug caps into my existing high-tension setup, and replaced the D8EA plugs with DR8EA to match the aftermarket cap impedance.

Ran the bike today in glum weather - very light drizzle and plenty of surface water, however I feel the problem is more constant after review to assume conditions affecting the ride. Frustrated to say that the bike was unhealthily backfiring in no time, and cut out on me in the same fashion twice.

In my limited opinion this leaves a few things left unsolved, and wondering what the forum wizards might look into first:
1. Air/fuel mix - should no longer be an air issue. Carb still running rich? Maybe due an overhaul afterall. The km's travelled on the bike has me skeptical.
2. High tension side - coils (which are joined to the leads) haven't been replaced, but both read similar impedance values which checked out against another thread if my memory serves me correctly. Is it possible and/or prudent to change the leads out?
3. Maybe lacking effective exhaust/back pressure?
4. Something further down the ignition system? CDI, or pulser (could have this completely wrong)?
5. Timing issues?

Thanks again for all your help
 

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I was thinking the same thing. AFAIK all '82 models are Transistorized Ignition (AKA full electronic ignition), not Capacitor Dischange Ignition.

After my findings going back to the bike again today, I suspect you might be right. There is a minute cracking in the spark lead just after the junction to the coil.
I missed this before but if the spark plug wire's insulation is cracked that is very likely what causes you problems when it is wet out. Even the best silicone rubber can crack after 35 years and even if the crack doesn't look that deep there are likely tiny fissures that go all the way to the copper core. When the wire(s) get wet the water works its way into those cracks and forms a conductive path to ground, effectively shorting the spark before it gets to the plug. I remember limping home on 1 cylinder when this happened to my '77 GoldWing in the early '90s. I wasn't surprised because the wires were old. Your wires are well over twice that age now.

If you do actually have CDI the spark plug wires are permanently attached to the coils but there are a number of coils available fairly cheap that will work well. If your bike really has TI the wires can be replaced easily and all you need is a couple of feet of 7mm copper core spark plug wire and you can usually get it where they sell lawn mower parts.
 

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Don't be so complicated :D

A short look to the rear between engine an coolant reservoir shows the type of the ignition.

A flat steel cover is a CDI.
a bigger -more rounder- alloy cover is TI/NEC ignition.
 

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Take the fuel tank off and grab a hold of the ignition wires with your bare hands. Crank the starter. Feel a strong jolt? There is your problem. The wires need to be replaced.
You may even be able to see the spark jump in a dimly lit garage. Ever use a timing light with an inductive probe clamped over a spark plug wire? It senses the current pulsing through the wires, so you know there is a certain amount of leakage even when brand new.
 
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