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Discussion Starter · #1 ·
Hello, noob here.



I have a 78 cx500, I was looking for a cheap running bike and found one.

It is difficult to start, it coughs and sputters for a 30 seconds or so before you can ease the choke off.

One it is idling well, It seems to hit a rev limiter at about 6k rpm. It is very consistant. It has given me as high as 9k rpm, sometimes no more than 4800 rpm, but the condition is identical when attempted within a short time period. Sometimes I can get a few hundred rpm extra by altering the throttle application, but it always feels like it runs into a celing, at a very specific point.

I have checked the cdi as shown in the factory service manual, many circuits have no continuity at all. I figured if the cdi had failed this badly, the engine would not run at all.



I see cdi units seem to be a problem on these, judging by the price of used units. I was wondering if this is a common symptom with a common fix. I am really looking forward to riding this spring and would love to go faster than 55 mph.



Thanks,

Bob
 

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Bob

Forget the CDI test unless you have the meters used in the manual

CDIs tend to work or not work anyway, partial failures are uncommon.



You'll find most money will be on a bad stator with those symptoms

so do (and note) the stator resistance tests first.



A shorthand test is to measure the open circuit resistance of the blue and white wires from the stator.

(the usual suspects)

White to ground should be 370 to 480 ohms (ish)

blue to white should be 77 to 91 (ish)

If you get figures way out of the above ranges then its probably a failing stator



BTW

Where you at?
 

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By all means test the stator first, but this could also be one of those carb &/or fuel starvation problems.
 

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I'd bet on the stator.



You don't mention where you're located, there may be a lister near you with an Ignitech CDI.

Swap in an Ignitech on your bike and your CDI on the other bike and you'll know for sure in less than 5 minutes.
 

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Discussion Starter · #5 ·
Look at me. Forgot to set up a profile.



Thanks for the heads up on the stator. Looks like a bit more work to replace, but its 100 bucks cheaper... I'll look forward to getting to this by next weekend.



I figured that the CDI would just flat fail. The whole NO continuity across a circuit didn't make alot of sense.

I have had the carbs off, done the Ebay rebuild, soaked the bodies in Seafoam spiked kerosene for three weeks while they were apart. I figure the hard start/cold idle is a result of funky carbs.



Thanks,

Bob
 

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Look at me. Forgot to set up a profile.



Thanks for the heads up on the stator. Looks like a bit more work to replace, but its 100 bucks cheaper... I'll look forward to getting to this by next weekend.



I figured that the CDI would just flat fail. The whole NO continuity across a circuit didn't make alot of sense.

I have had the carbs off, done the Ebay rebuild, soaked the bodies in Seafoam spiked kerosene for three weeks while they were apart. I figure the hard start/cold idle is a result of funky carbs.



Thanks,

Bob


The stator is actually more expensive than the Ignitech through the group buys, or if you get one yourself. $100 cheaper? Where you getting rebuit stators for $50? The CDI stator is usually at least twice the price of a "normal" stator because of the High side wiring. Plus, you're looking at at least $100 in incidentals like the gasket kit etc. if you take the engine apart. If you have no history on the engine, chances are once you open it you'll be doing a triple bypass, the stator, water pump and can chain service. If you do it right, you're looking at about $400 in parts. And when all's said and done, your 30+ year old CDI will likely die sooner than later, and you'll end up buying the Ignitech anyway.
 

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Discussion Starter · #7 ·
I guess I need filled in on this Ignitech system. Anybody have a link?

Timing chain and WP were done about 5 yrs ago, 3k miles. This wouldn't be due again soon would it?
 

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I guess I need filled in on this Ignitech system. Anybody have a link?

Timing chain and WP were done about 5 yrs ago, 3k miles. This wouldn't be due again soon would it?


You're golden on the WP and timing chain for at least another 15 years if you're riding that kind of mileage.



If the charging side of your stator is OK and the high side is the problem, the Ignitech will resolve this without having to do anything but replace the OEM CDI with the Ignitech.
 

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Discussion Starter · #9 ·
Havin a bit of trouble sorting through threads to find info on the Ignitech. Im assuming it is a box similar to the CDI, performing the functions of the CDI and high speed winding of the stator, leaving the stator to charge the battery. So if I get the Ignitech, I will replace the CDI, leave the stator in place to charge the battery, and simply disconnect the high side of the stator? If so, I'm all in on this.
 

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Did you check the stator? I would still recommend getting a Ignitech anyway, like Cobram said, eventually that CDI will give up the ghost. I've got probably 8-10K miles on my ignitech so far and nary a problem.



I replaced my stator with a Non-CDI version, which you could do down the road if you had an ignitech - the non CDI stator just has the charging coils, so it puts out more watts for accessories.





Mike
 

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Discussion Starter · #12 ·
All of my resistances were out of whack if I recall. The battery still charges though. When you disconnect the 3 yellow wire connector, is the bike supposed to crank and not start, or not crank at all?
 

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All of my resistances were out of whack if I recall. The battery still charges though. When you disconnect the 3 yellow wire connector, is the bike supposed to crank and not start, or not crank at all?


I am removing an OEM "working" ignition today. If you want it, you can have it for $10, shipping included. I am building a 1980 project bike, testing to date with this ignition on the following videos. Will be installing a Ignitech from Cobram.



http://s657.photobucket.com/albums/...500 Project/?action=view&current=MVI_4798.mp4



http://s657.photobucket.com/albums/...500 Project/?action=view&current=MVI_4796.mp4



http://s657.photobucket.com/albums/...500 Project/?action=view&current=MVI_4793.mp4



Email, if you want it. Going to the post office about 1:30PM eastern time.
 

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If the OP doesn't take you up on it my PayPal is open, send me an e-mail if you still have it after he's had sufficient time to respond. I don't need it but a friend here does badly for an old CX he's going to be starting on the restoration of pretty soon.
 

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Thanks, he's been so nice to me helping me out to restore mine all year and while I've collected some extra parts I'm lacking in that department and a few others. So few here in Oklahoma and eBay is a cr*pshoot or a ripoff.



I still keep my eye out for good deals, even have an area upstairs at work I'm dedicating to extra parts for these bikes so I can help out others as the years go along. Sure will be nice if someone's looking for something unavailable anywhere else and I can just pass them on to those members in need on the forum. Nice storage area near one of my main boilers so the humidity is low, airflow is limited and I wrap everything up in permeable wax coated paper so they don't disintegrate.
 

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Any response? The guy is seriously wanting to put two of his CX500s parts bikes into one and both were retired for the same problem.
 

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Any response? The guy is seriously wanting to put two of his CX500s parts bikes into one and both were retired for the same problem.


No response yet. Sent Bob an email Tuesday.



Riding in the foothills today, forecasted highs

in the 50s.



Will check emails tonight when I get home and send

you an email Thursday morning.
 

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Thanks, I'd love to see him put one of them (or parts from both) back into our running fleet rather than having them both rust out over time. As mentioned I've got somewhat of a cache of parts built up but I've still got a lot of room left to store a ton more stuff in a controlled environment for those in future need however this issue is somewhat pressing.



Hard to imagine a guy that's about willing to part with his BMW and 650I in favor of his CX's as in his opinion they're so much easier to handle and work on if the need arises. He needs valve stem seals on the BMW and that's a major job from the way he describes it. He is getting new tires for it and won't sell it until its perfect. Not a real issue yet but he's a perfectionist when it comes to bikes, I think he treats them better than he does his horses.



I don't know the model of his BMW but his 650I is almost factory perfect. He's sentimental about these things but will list them on the forum when (and if) he finally decides to part with them.
 

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It's always a bit after noon Central time when this server starts to act up, they must be doing backups or have a tremendous amount of data flowing in & out during this time.
 
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