CB200 carb issues

[Oddjob]

They don't appear to stock any NGK caps at the moment Phil, seems to be a shortage. M&P Direct have them though. Oddly I was looking at them this afternoon for another member.

[Johnwebley]

   are you talking about the plugs?

    or the caps,

   the caps I got from Wemoto,

   can't remember were I got the plugs from

[Oddjob]

Caps John. Seems NGK aren't making any at the moment, not sure why?

[Oddjob]

If you order caps John you need the D version not the B. As in XB05F or XD05F, the first letter identifies the type of cap, in that case a 102 degree elbow type, the B stands for 14mm plugs and the D for 10 and 12mm plugs. The F in this case stands for them sliding onto the bare threads at the top of the plug instead of using those little caps plugs come with.

If you want a 90 degree plug cap that starts with an L and the slightly angled ones are 120 degrees is Y.

That make sense?

[Laverdaroo]

Beware of wemoto stuff. I’ve had loads of bits from there in the past that ended up simply being crap. You think you’re saving money but you’re not. I don’t buy anything from there anymore.

The most memorable being a set of front brake seals for the VFR. They absorbed so much fluid and swelled that the brakes warped the discs on the first run out!

I only buy OEM stuff to replace OEM stuff now…..including caps and the like.

Only from experience I’d get your caps somewhere else to be sure. I wouldn’t know how to test them but someone will tell me soon no doubt


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[Oddjob]

NGK caps are supposed to be 5K resistance. You could try measuring one and seeing what it is and then when it's hot to see if it changes.

Just bought some NGK caps for future use, might as well get them whilst they are available, seems it's something to do with the stuff the body is made from, shortage or no longer made I believe.

[Sesman]

Yes, Ken. I can believe it. I had to wait 4Months for the last lot…yes, 4 months😳

[McCabe-Thiele (Ted)]

Looking back on the post not sure if you need higher or lower coil resistance - be handy if you knew what they were when the bike was built so you could source the right one.
Probably not relevant but as V= IR a lower resistance would mean a bigger current ?
Would higher resistance meaning lower current demand help supply more spark at higher revs - I'm way out of my depth here just thinking out loud in the hope it can help.

IIRC the 400 runs on 4.6 Ohms so if a 200 has half the cylinders & 1 coil would that be a similar  sort of figure?

My online search suggests the CB200 coil is 4 ohms according to the below three sellers.

.https://www.amazon.com/Ignition-Coil-Honda-CB160-CB175/dp/B079M69MW1

.
https://4into1.com/ignition-coil-honda-cb-cl160-175-200/

.
https://www.aliexpress.com/item/1005003463624926.html

[Sesman]

Hi, Ted. Unfortunately not. The voltage on the secondary HT side is a function of the coil inductance ‘L’ and the rate of current collapsing when the points are opened. The resistance of the coil simply self limits the primary current and alters the collapsing current time constant….The trick with coils is to ensure that the secondary HT side insulation is sound. The magic in coils is much, much more to do with transformation ratio (eg the number of primary/secondary turns and the quality of the transformer core (yoke) material and design. That gets us the ⚡️. Energy is a function of  voltage squared/ resistance x time. The voltage on the secondary side is very large, but so is the coil secondary resistance.The time is very short of course (joule integral). Basically that’s what produces the bang.

I could be wrong, but I’m sure there is a thread somewhere, where Ash constructed an ignition coil tester to simulate the ignition process and coil performance. Apart from open circuit (continuity testing), I’m guessing the most common cause of failure is insulation failure, whether that be in the coil structure our downstream on the HT leads, caps and plugs.

Just for completeness, the back EMF created in the coil primary circuit as a result of collapsing current (points opening) drives a current. It’s this voltage and current that arcs across the points causing damage to the points surfaces. That’s why it’s important to have a good condenser (capacitor). The arching also extends the collapsing current time constant, which is counter productive to good spark production.

I know, I know. A tedious subject that many are fully versed on, but if it helps somebody out there to understand the basic mechanism it will improve their fault finding. Apologies to all who may feel patronised, this item was not for their benefit.🫣

[Johnwebley]

Thanks gentlemen,
When it gets a little dryer and warmer I shall check all my plug caps for resistance,

What is the refresh rate on the coil?

Can you estimate how many times a second is to many?

The difference between 4 and 5 ohm,

Back later

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[McCabe-Thiele (Ted)]

I had a feeling it could not be simplified Phil - but it looks like they are 4 ohm coils on the CB200.

How about lower ohms means more current so then                    Watts = Volts x Amps so more power for the spark? I'm conveniently forgetting that it's the primary current etc.

[K2-K6]

The coils have no proboem keeping up with rpm technically as you'd likely need to get beyond about 14,000 rpm before needed to consider this.

Lowering ohms on primary will usually result in the coil producing excess heat as it just doesn't need this, rather than greater spark.
Very high rpm , there's maybe a case to consider this, but not generally running an engine like this one.

[Sesman]

Joules, Ted, joules. Time is the thing. Kw is just power. Time is what does the work. Eg you could have infinite power, but if time is zero you have zero energy.
.

[McCabe-Thiele (Ted)]

Joules that's SU units  I'm more of a Horse Power type of bloke.

Going back to the post we seem to be edging towards it's more about coil design quality & cap ends so even if they should be 4 ohms 4.6 ohms might work okay?

[Sesman]

Nope. Lowering the primary resistance will of course increase the primary current for a given voltage, but then the coil windings would be designed for the increased thermal performance being of greater cross sectional area. The problem with coils is leaving the ignition on for a protracted time as you lose the benefit of the on/off cycles. Due to the required HT insulation/encapsulation properties, the coil is a very poor heat sink. You can unintentionally raise the coil temp and duration, prematurely aging the insulation leading to premature failure. Oh and it will flatten your battery.

JW, I strongly suspect this is ignition related. Check those points and condenser, substitute, the plugs and caps and lastly swop out your coil. I haven’t mentioned HT leads as I presume they are composite, being embedded in the Honda coil?