Looks like it is my labyrinth seal

[m in sc]

50 year old capacitors are typically at end of life or done .

i would source some new auromotive ones and try them if points are the way to go for you. 

also, if you havent changed the actual wire from the points to the coils, do so. replace them. ive been bit by that more than once. tests ok, but running, it jumps or breaks down.

lastly , filing points is bad . i know it was common practice, but the surface is coated. you file or sand it, that goes away. while its a quick fix, it is absolutely bad practice that is far too common.

[RDnuTZ]

you've thoroughly tested and retested everything. That should have caught whatever it is if it was something obvious, common, or simple. IMO you've reached the limit of what static testing will get you. In a recent post you said it starts easily and consistently and runs good most the time, but not as good as you expect all the time. The fail mode is reduced to "sometimes". Armature windings failing with heat? There's an old saying "too much analysis leads to paralysis". I get you want to stay with points, but what choice is left but to try the most affordable no points option? There's no guarantee it will be THE fix, but if it does you at least will know everything else in your system is operational. If it does make it run the way you expect you have your baseline and can always work on converting back to points system when you have the time and motivation to dig in again.

Good Luck!

[m in sc]

so, at deals gap this year, there was a guy w a really pretty modded rd350. he couldnt get it to run for shit. we went down the list of everything and it kept coming back to ihnition, for at least me and Chuck Quenlzler.  heres the kicker, it had one of those stupid Indian radjoot cdis on it 'because it was half the money' all week. fired up great, then the longer he ran it the worse it got.

few weeks later he dms me on fb, says he put a cdi on it (hpi i suggested) said it absolutely fixed it. what i had said was id rather run points than that crappy cdi, and we know how i feel about those. 

[gargantua350]

I installed an HPI and it was great until the rotor magnet cracked/separated.  I installed the VAPE ignition and my bike runs more smoothly in my opinion. I did a 450 miles early this year in the california desert on route 66 with no issues.  since I installed the VAPE, the plugs burn more evenly than with the HPI.  the best part is that you can run without a battery on both systems and the spark energy is pretty high.  With points ignition I was always chasing issues.  I once had the right side points intermittently shorting to ground and causing either plug fouling or missing and backfiring.  with any of these modern ignition systems these problems are now a thing of the past. 

[RDDave]

I guess I would be a happy camper if I got rid of the points and all was good. But if I bit the bullet and that wasn't it, I am not sure I could show my face here again.

Lots of you guys keep telling me that it may well be the ignition and have your own horror stories to back it up.

I guess I am hard headed, but I just have a hard time accepting that the stock ignition on a stock bike just will not work right no matter how well sorted out it may be. But, I highly respect the knowledge and experience here.

IF electronic wasn't so expensive, IF I hadn't read several posts here on their failures, and IF I could test one to see, it would be a much easier decision.

I may look more seriously at the Vape. Seems you all think it is worth the coin over the others.

I will spend some time with the search function and would look at any particular threads that you would recommend.

I appreciate all the input.

.

[RDDave]

$800 for Vape. OUCH!

.

[m in sc]

you're missing an important aspect. a 50+ year old harness and ignition parts (not all). one part out = issues.

the cheapest way out going electronic is with one of these:

https://ebay.io/m/LlWVD9

im not a huge fan of the concept of a cheap ignition from china.. but... they have gotten pretty good. i have one on my t500 (the 71) because i did put a vape and a zeel on my 72 + a different coil, well over 1100 in ignition stuff, and that was before they got even more expensive a few yrs ago.

i also bought one for my LS2, they were the only ones making a point replacement and dammit, it works.  yes with sv coils as well. (on both actually).   

[RDnuTZ]

I guess I would be a happy camper if I got rid of the points and all was good. But if I bit the bullet and that wasn't it, I am not sure I could show my face here again.

Lots of you guys keep telling me that it may well be the ignition and have your own horror stories to back it up.

I guess I am hard headed, but I just have a hard time accepting that the stock ignition on a stock bike just will not work right no matter how well sorted out it may be. But, I highly respect the knowledge and experience here.

IF electronic wasn't so expensive, IF I hadn't read several posts here on their failures, and IF I could test one to see, it would be a much easier decision.

I may look more seriously at the Vape. Seems you all think it is worth the coin over the others.

I will spend some time with the search function and would look at any particular threads that you would recommend.

I appreciate all the input.

.

I totally understand your frustration and desire to get the stocker to work if you can just verify the fault. Here's the flaw I see in your reasoning and reluctance: you are assuming you are starting with a proper working OEM ignition that just has a problem you haven't found and fixed yet, right? You mentioned you replaced the Left crank seal, so you obviously had the complete stock ignition removed and in your hands. You saw both sections had the copper windings in them. It's a great leap of faith that 51-year-old copper wound components/assemblies are 100% still intact and reliable at all speeds and temps. You don't have access to a known good complete generator assembly. What choice do you have but to buy a new replacement ignition that will confirm yes or no yours is actually good if you find the mysterious fault and fix it?

I'm expecting to face a similar situation soon: I have a 1973 RD250, 2 1974 RD350 and a 1977 RD400 in my shop and NONE are complete! I have spare motors, ignitions, etc. Only the 400 was running when I bought it so I have reasonable expectations that will be a running baseline when I get it back together. The others will get a reasonable effort to get running with OEM ignition. If I get too far into any of them and not running- I'm going straight to another ignition and it's NOT going to be a top-of-the-line performance system either. Can't afford it and don't need it- I just want a basic runner out of all the bikes to start with.

There are some brilliant people on here that live and breathe this stuff who I really admire, but I can't match their passion and enthusiasm with so many bikes to get going and limited time at 68 years old. My wife gave me the ultimatum not to die and leave her with all this "junk" to dispose of so I have to fix what I can reasonably in time available and thin the herd over time.  I will probably be too embarrassed to broadcast if I choose Newtronics for quick and dirty solution, but will feel Ok if I go Dyna S solution to get these babies back on the road before I die 

[RDnuTZ]

you're missing an important aspect. a 50+ year old harness and ignition parts (not all). one part out = issues.

the cheapest way out going electronic is with one of these:

https://ebay.io/m/LlWVD9

im not a huge fan of the concept of a cheap ignition from china.. but... they have gotten pretty good. i have one on my t500 (the 71) because i did put a vape and a zeel on my 72 + a different coil, well over 1100 in ignition stuff, and that was before they got even more expensive a few yrs ago.

i also bought one for my LS2, they were the only ones making a point replacement and dammit, it works.  yes with sv coils as well. (on both actually). 

I saw those and they scared me lol. I'm still keeping in mind the Newtronics from Yambits for a low budget fix if needed.

[m in sc]

I think one test that you can do is ride it until it doesn't run right, then install brand new spark plugs that are gapped a bit smaller and see if it improved at all. If so, then it would point towards a weak spark.

I agree w this

[rodneya]

$800 for Vape. OUCH!

.

Gotta pay to play

[1976RD400C]

Outside the box: Petcock flowing good and continues to flow good?

[RDDave]

I have had big block and Hemi Mopars all my life. I still have a '70 HemiCuda with a 540" Hemi. And one thing I have always done when I tore something up was to do forensics. I wanted to know what happened. I have learned far more from that than most anything else. That is what I am pulling against in this. I really hate to give up. Wanting to know what is actually wrong is driving me as much as just plain wanting it to run right. Otherwise, I would have moved on last year. Which might have been the smart thing to do.

BUT! Maybe I am whipped on this one and it's time to move on.

Does that Ebay ignition have battery charging? It doesn't look like it.

The Vape would be my preference based on the collective experience here. I guess if I had tore into the engine to change the labyrinth seal, that would have been over half the cost of the new ignition, been a LOT more work, would not have fixed the problem, and it would still have points ignition.

So A HUGE THANK YOU to you guys: THANK YOU!

I am not on any kind of a budget. But it is difficult for me to spend $800 on an ignition for a $4,000 +/- bike. But then, compared to Hemi stuff, that is pennies on dollars.

So, I guess I am going to tinker with this a little bit more. The bike is still with Rodney who looks at it a little here and there as his energy and time allows. Maybe something will show up.

Meanwhile, I am going to review the threads here and the youtube videos on the Vape install.

 

[m in sc]

that ebay ignition is strictly a points replacemen. it should run on battery alone. its the cheapest way to go imho, and one ive used.

[RDDave]

I thought so. Not something that would work for me on my street bike.

Although, if I could rent someone's as a test to see if it cured my problem, I would LOVE to do that.

It would just be a waste to buy one as a test knowing that it would not get me where I want to be.

.