Author Topic: Weird intermittent spark (Read 5662 times)

calj737 · « **Reply #25 on:** March 19, 2016, 12:09:42 PM »

Plug cap measurements please...

Sdsbassist · « **Reply #26 on:** March 19, 2016, 12:10:21 PM »

I've swapped caps too. Measurements? What type of measurements can I get you

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calj737 · « **Reply #27 on:** March 19, 2016, 12:11:55 PM »

Resistance of each cal measured with a meter. While you're at it, measure coils too please.

Deltarider · « **Reply #28 on:** March 19, 2016, 12:12:05 PM »

Quote

Resistance of each cap measured with a meter. While you're at it, measure coils too please.

+1
BTW, what bike are we talking about?
Can you inform us if you've done other things (like maintenance or 'repairs') before this started?
The last thing you did, is often the cause.

Sdsbassist · « **Reply #29 on:** March 19, 2016, 12:13:06 PM »

Well this was my first start up for bike. Cleaned carbs, bench sync, gapped plugs at .26,

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Sdsbassist · « **Reply #30 on:** March 19, 2016, 12:15:20 PM »

Sounds good. Guessing my manual will give me details on the proc?

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Deltarider · « **Reply #31 on:** March 19, 2016, 12:21:12 PM »

Caps resistance ideally is around 5KΩ. 10KΩ is the max! BTW, what type of sparkplugs do you run, with or without R(esistor)? HT leads measured from one to the other (caps removed) should be around 14-15KΩ. So with caps attached you should read around 25-30KΩ in a secundary circuit. Primary circuit is around 4,7Ω.

Sdsbassist · « **Reply #32 on:** March 19, 2016, 12:26:33 PM »

First cap.

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Sdsbassist · « **Reply #33 on:** March 19, 2016, 12:30:49 PM »

Next cap I checked: orig on cyl 1 11.8

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Sdsbassist · « **Reply #34 on:** March 19, 2016, 12:38:12 PM »

Then 2 cyl read 5.5, 3 cyl read 14.4.......caps?

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Stev-o · « **Reply #35 on:** March 19, 2016, 12:54:58 PM »

Quote from: Sdsbassist on March 19, 2016, 12:13:06 PM

Well this was my first start up for bike. Cleaned carbs, bench sync, gapped plugs at .26,

Why dont you think you need to replace the parts for a proper tune up?

Sdsbassist · « **Reply #36 on:** March 19, 2016, 12:56:55 PM »

Ya I'd love to replace every part on the bike, but I just don't have the money. So if it works, I plan to use it.

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Stev-o · « **Reply #37 on:** March 19, 2016, 01:02:40 PM »

Quote from: Sdsbassist on March 19, 2016, 12:56:55 PM

Ya I'd love to replace every part on the bike, but I just don't have the money. So if it works, I plan to use it.

Dont need to replace every part. Plugs, caps, points and condensers - $100 and I bet that bike will be running good.

I've been there, thought the points "looked" good, bike wouldnt run right. Changed points and condensers, guess what? Started right up and ran very good.

Sdsbassist · « **Reply #38 on:** March 19, 2016, 01:03:28 PM »

Ya. Your probably right.

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Sdsbassist · « **Reply #39 on:** March 19, 2016, 01:09:10 PM »

Thinking right now of putting it away till then. I just can't put any more cash into it right now

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Sdsbassist · « **Reply #40 on:** March 19, 2016, 01:09:23 PM »

Quote from: Sdsbassist on March 19, 2016, 01:09:10 PM

Thinking right now of putting it away till then. I just can't put any more cash into it right now

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Are those caps way off though?

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Deltarider · « **Reply #41 on:** March 19, 2016, 01:30:23 PM »

Best is step by step if we want to learn something. Caps that read more than 10KΩ are no good. Personally I don't want them over 8KΩ. Mind you, that is in combination with plugs without R(esistor). Furthermore caps in one circuit (1+4 or 2+3) should not show more difference than 1KΩ resistance.
Plugcaps do deteriorate in use but are about the cheapest parts.

Sdsbassist · « **Reply #42 on:** March 19, 2016, 01:46:59 PM »

Resistor screws in at top of plug, right? I think I'll wait a bit and when I score some case replace all spark related stuff and see if it helps.

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Sdsbassist · « **Reply #43 on:** March 19, 2016, 03:19:17 PM »

Thinking about how it sounded and seemed to run ok on three cylinders with junk caps, this thing is really gonna roar when I get back at it

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camelman · « **Reply #44 on:** March 19, 2016, 11:33:55 PM »

Sdsbassist, those caps are pretty cheap at various places. I personally like 4into1.com and they have low shipping costs. You'll get a much better spark and performance from each cylinder if you change your caps out, and you should probably change them all if three out of four measure high. Make sure to trim off the last 1/4" of the spark plug wire when you put new caps on so that you get a good contact with the wire and don't introduce more resistance to the circuit.

A little background: as the resistance of the caps increases, it is more likely that you'll get arcing through the spark plug wire insulation to whatever "ground" is nearby like the engine, frame, other wires... This is because the electrical charge is looking for the easiest path to ground, and the resistor cap is putting up a bigger and bigger fight as resistance through it increases.

Camelman

Deltarider · « **Reply #45 on:** March 20, 2016, 12:53:21 AM »

Quote

when I score some case replace all spark related stuff and see if it helps.

Do it step by step so you (and we) will learn what caused your problem. There are owners who just throw a lot of money in their bike by replacing all related stuff in one time, hoping the bike will see and value the offer. Alas, a bike is not like that.

Sdsbassist · « **Reply #46 on:** March 20, 2016, 05:44:15 AM »

Quote from: Deltarider on March 20, 2016, 12:53:21 AM

Quote
when I score some case replace all spark related stuff and see if it helps.
Do it step by step so you (and we) will learn what caused your problem. There are owners who just throw a lot of money in their bike by replacing all related stuff in one time, hoping the bike will see and value the offer. Alas, a bike is not like that.

The caps are obviously bad. I think I'll start with those and ngk plugs

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Vinhead1957 · « **Reply #47 on:** March 20, 2016, 06:12:26 AM »

If you changed the plug cap and plug with a working cylinder and nothing changes, then swap coils and if the problem moves to another cylinder it is the coil. It is a low probability but they sometimes go bad. One set of points fires two cylinders so the problem is not there. Another option is to check spark with the plug out against the head. If it is a nice blue spark look into the carb. Bad fuel or varnish clogged carb

calj737 · « **Reply #48 on:** March 20, 2016, 07:27:11 AM »

Quote from: Vinhead1957 on March 20, 2016, 06:12:26 AM

If you changed the plug cap and plug with a working cylinder and nothing changes, then swap coils and if the problem moves to another cylinder it is the coil. It is a low probability but they sometimes go bad. One set of points fires two cylinders so the problem is not there. Another option is to check spark with the plug out against the head. If it is a nice blue spark look into the carb. Bad fuel or varnish clogged carb

If you look at his post with cap resistance readings, the evidence is obvious.

Sdsbassist · « **Reply #49 on:** March 20, 2016, 07:28:13 AM »

Yes. I ordered new caps and plugs. If that doesn't work I will move to points and condensors

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Author Topic: Weird intermittent spark (Read 5662 times)