Author Topic: silicon replacement of original rectifier on 200RS  (Read 3398 times)

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Offline johnrkeele

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Re: silicon replacement of original rectifier on 200RS
« Reply #20 on: June 27, 2023, 04:01:14 PM »
The testing today showed the same happening as before the ignition paths were switched. So, I'm thinking a first thing left to check out
is the right side points and it's connections.
One more thing that I will mention...at first start, it has always been the case that I've needed a puff of starter fluid use to get
the first start. After that, it starts immmediately on its own. This is different than on other 2-strokes I've worked with.
John K.

Offline czmike

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Re: silicon replacement of original rectifier on 200RS
« Reply #21 on: June 27, 2023, 07:24:07 PM »

Yep John, you're on it.
That test will show up a bad coil if that is what you have.
If the fault does not shift to the other cylinder then it is likely you have a bad condenser.

Coils & condensers can be bench tested but you need the right test equipment.
These days few people have that. You would need to find an old-school ignition guy to get meaningful testing done.
So substitution, like what you are doing, is the best approach. Although substituting with new parts is a better approach.
Condensers don't last forever either as just like coils they have hard life.
All this electrical work is good for your little two stroke. They love good sparks.

Good Luck!
Mike

Offline johnrkeele

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Re: silicon replacement of original rectifier on 200RS
« Reply #22 on: June 27, 2023, 11:25:12 PM »
Mike, the test I did switched everything to the other ignition path, including switching to/thru the condensers.
The only thing not switched was the contact points. And the behavior was as before switched...the right cylinder would be firing/running
at the initial start, but would very soon start to randomly miss, especially with some throttle, and then not long after that. it (that
cylinder) would cease firing completely.
So I think the first next step is to check out the right cylinder ignition points. (The points were in good condition originally; were easy
to clean up and re-use, so I'll be surprised if the point surfaces are already bad to the extent of misfiring.) Will see what I find. 
John K.

Offline czmike

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Re: silicon replacement of original rectifier on 200RS
« Reply #23 on: June 28, 2023, 06:08:54 PM »

Hi John,

I'm confused. I sincerely hope you aren't.
This cylinder swapping approach on a twin can be confusing.

It's hard to believe you did all that de-soldering to achieve a left/right swap of the coils & the condensers
which would entail extending the short leads from the condensers to the points to the opposite side of the alternator?!
Did you really do all that?
I would have just swapped the coil leads up at their coil ends where there are bullet connectors.

If you really did swap the condensers as well as the coils then certainly you should focus on the points - particularly checking their insulation from ground and their opening gap.
The points though are a less likely cause of the symptoms you describe.

I think you didn't actually swap the condensers side to side and these will be your problem.
Your description of the fault does sound very much like condenser trouble.
But don't let me confuse you - it doesn't matter if I'm confused as long as you are thinking and acting logically you will succeed.

Best Regards,
Mike

Offline johnrkeele

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Re: silicon replacement of original rectifier on 200RS
« Reply #24 on: June 29, 2023, 01:05:04 AM »
Hi Mike, thanks for getting back on this. I agree that my problem description does sound like what happens from a bad condenser.
What I did was simply swap the plug wire-and-cap from the right/leaky coil/bad cylinder over to the spark plug in the left cylinder (the
spark plugs have been changed back and forth and to 'hotter' plugs several times before this 'test', without any change in results, so
I don't think the plugs are the problem)...and then simply swapping the black wire that goes from that coil down to/thru the 'black wire' condenser
and normally to the 'right cylinder' points,...connecting/swapping it instead to the 'left cylinder' points. It seems to me that that gets
the 'problem suspect/normally right side' condenser over to supplying the left cylinder...and when I did that,
the left cylinder still continues to be the cylinder that is working.
I'm anxious to find out if I'm missing something in my analysis...there's little pride to be lost.)   :)
Thanks,
John K.

Offline czmike

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Re: silicon replacement of original rectifier on 200RS
« Reply #25 on: June 29, 2023, 04:00:56 AM »

Hi Mate,

Ha, Ha then - I told you this can be a confusing process!!
Let me try to understand & try to help.
That's all I'm doing (trying to help), I'm not trying to show off, be smart, show you up or run you down.
 
I'm reading in to your words that:
1. You didn't physically move any condensers about.
2. You didn't disconnect any condensers from their original points set. Originally short (black & white) wires were run from each condenser to its points.

If 1 & 2 are true then you only swapped over the coils (electrically).
Which is good (swapping one thing at a time is the best approach).
If all this is true then you have proved that both coils will fire the good, left cylinder.
And during that test the left points & the original left condenser were still being used (to fire the left cylinder).

So we might suspect the right condenser which is still wired to the right points set.
If you have another condenser it would be good to connect it up to the right points and disconnect the original right condenser.
Any condenser from a car (with a distributor) or other bike will be close enough in value and its physical arrangement
doesn't matter as long as you ensure you make the case connect to ground.
You are just trying to do a short term test to discover what's wrong.
0.2uf (or 2 micro farad) is a very common value for an ignition condenser.

If you can't get hold of another condenser then you could swap them over but this will probably get messy & may confuse.
You could unscrew them and shift them from side to side or, disconnect the short wires from the points and temporarily extend them
so they will reach the other set of points.

Thanks for letting us know how you are progressing John!
Wishing You Luck!!

Offline johnrkeele

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Re: silicon replacement of original rectifier on 200RS
« Reply #26 on: June 29, 2023, 12:00:22 PM »
Mike, thanks for getting back.

1. I didn't move the condensers at all.
2. I DID disconnect the condensers from their original points set.  I switched the black condenser wire to the left/opposite
    points set, and the white wire to the right points set. 

I haven't checked the points themselves yet...I suppose there might be a chance that the condenser is bad enough that
the right points have already deteriorated enough to be the problem. Will check it as soon as I'm able to get to it.

John

Offline czmike

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Re: silicon replacement of original rectifier on 200RS
« Reply #27 on: June 29, 2023, 05:20:12 PM »

Thanks John for clarifying that!

So you are correct to focus on the points themselves.
Check the insulation of the un-grounded contact remembering that there is 200 to 300volts here not just 12!
A very wide gap would produce your symptoms.

Maybe though the ignition is actually OK, or at least good enough.
Your stumbling engine might be a fueling problem after all and the best way to test that is the method I mentioned earlier:
Listen to the ignition with an AM radio. If the buzz from the sparks is consistent then it is a fueling issue.

I made a mistake in my last post, sorry. The condenser value should have been written as 0.2uf or 0.2 micro farad.
A replacement condenser must have a 250 volt rating. Most automotive ignition condensers (not suppressors)
have values around these or very close.

Best Regards,
Mike

Offline johnrkeele

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Re: silicon replacement of original rectifier on 200RS
« Reply #28 on: July 05, 2023, 11:58:35 AM »
I'm happy to report that the Mk2 ran just fine as I rode it down the road yesterday evening (~2.5 miles round trip). One of the
insulation disks (it was the one that happened to be in the 'outer' location under the spring) on the right cylinder points set connection
had a visible crack. And Mike, it was a revelation to me that the voltage in that area is a lot higher than 12v!

(There was also another thing that was adding to my confusion on trying to analyze the problem...I finally figured out that
my fuel hook-up for the stationary testing was not working consistently, and sometimes depriving one or the other of the carbs
with fuel flow. And it was apparently happening to be on the cylinder that was being suspected/tested on the ignition problem...
which explains the cylinder going dead with further running, and attributing it to be part of the ignition problem.  A bit of DUH! here.)

Thanks for the valuable inputs.

John K.

Offline czmike

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Re: silicon replacement of original rectifier on 200RS
« Reply #29 on: July 05, 2023, 05:55:25 PM »

Whoopeee! Well done John!!

Thanks for letting us know how you did.
It's nice to share the joy of riding these things when they are running sweet.

Insulation failure in ignition primary circuits is often overlooked.
I use an insulation tester to check primary circuits and it tests at 500 volts DC.
This meter shows up bad ("leaky") condensers as well as other insulation failures (like "kill" switches in bikes with magnetos).
A multimeter tests at only a couple of volts so they won't show up insulation faults that only occur
when high voltage is applied.
Careful observation (as in your case) will usually find suspect insulation without having to resort to an expensive tester.
Knowing where to look though is handy (visualisation is super important during any electrical diagnosis - as you can't see electricity!).
The ignition condensers in your 200 are rated at 250 Volts D.C. Working (250VW) and all the wiring and terminals
in the primary circuit have this sort of voltage applied to them. Along with peaks of short duration up to 300 volts.
So it is important that all the insulation is in good condition.
So the dribbly coil lives on.

Enjoy riding it John!

Best Regards,
Mike

Offline johnrkeele

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Re: silicon replacement of original rectifier on 200RS
« Reply #30 on: July 17, 2023, 03:39:07 PM »
Onward with the Dec 1969 build Mk2...real enjoyable to ride...noticing the 'tall-ish' gearing with the 16-36 sprocket combination, which
I calculate to 11.5 mph/1000 engine rpm (with tape measured 79" tire circumference). In comparison, the 1971 Yamaha 200cc CS3 that
 I have, which with its standard sprockets, calculates to 9.4 mph/1000 engine rpm. So the Mk2 is geared 22% taller than the same
displacement Yamaha. I also definitely notice the taller first gear on the Mk2...gear 'range' on the Mk2 is 3.02 (first gear
ratio divided by top gear ratio), where it's 3.37 on the CS3.

Two things I need to accomplish on the Mk2...I'd like to find replacement exhaust header gaskets (1142-5000), and haven't found any
as yet.  Also, there is a seepage from the oil sight glass that's enough to make a drip from the bottom of the oil reservoir.  At first, I
assumed it was the oil tank outlet connection leaking, but then noticed the oil on the tank below the sight glass.
Has anybody had this problem and fixed it with some kind of a 'sealer' application to the existing unit? (I think I saw the high priced
new sight glass from Richard suggests sealing the new unit with 'permtex #2'.)

John K.

Offline johnrkeele

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Re: silicon replacement of original rectifier on 200RS
« Reply #31 on: July 25, 2023, 02:32:58 PM »
At the AMA Vintage Motorcycle Days meet last weekend I was able to fine exhaust header gaskets that I think I have
successfully modified to fit. They are for Yamaha YL1, and also Yamaha YG5 appears to use same the same gasket
John K.

 


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