Author Topic: Spark Plug gap of .024 inch = big improvement starting  (Read 3539 times)

davexz

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Spark Plug gap of .024 inch = big improvement starting
« on: July 16, 2017, 08:19:21 PM »
Been fighting with starting issues on my two Visions for a long time.  Finally, I think I solved the problem.  I changed the spark plug gap to .024 inch exactly and they start right up now.  Manual says .024 to .028 inch.  Buy my theory is that with all involved the system has a hard time generating enough voltage to fire the plug, especially when you crank the starter a bit.

fret not

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #1 on: July 17, 2017, 02:04:05 AM »
As we know, the ignition system is not very robust, so any little thing you can do to help it along should be of benefit.  New plugs with proper gap, good plug leads and caps, good clean wiring in general, and a well charged battery should help.  I seem to recall the POD has taken delivery of one of those Ignitech ignition units, which I hope will prove out to be more robust and reliable.
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artbone

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #2 on: July 19, 2017, 08:35:15 AM »
I think the problem is that your coil output just won't jump a gap of more than .024 under cylinder pressure. To really solve the problem you probably need new, better, coils and wires.

Until electronic ignition came along Brit bikes were famous for being hard to start. One of the "fixes" in days gone by was the famous Kmart coils. Someone discovered you could replace your wimpy little Lucas coils with some $10 aftermarket coils made for a 55 Chevy and regap your spark plugs to about .040 and suddenly your hard starter was a one kick wonder. It was like lighting a welding torch in your cylinder. That's probably what's happening with our Visions. I'm going to replace my old coils with modern ones and new plug wires and caps. I think that will make a huge difference.

I'll repost back when it's done.
« Last Edit: July 19, 2017, 08:41:53 AM by artbone »
Art Bone

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vintage bikeworks

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #3 on: July 19, 2017, 04:58:36 PM »
Installed Dynatek miniature series DC3-2 coils and haven't looked back.  Stock coils were always known to be marginal on 70's and 80's bikes.  A much stronger spark equates to easier starting, smoother idle and running.  I've made it a practice to replace the original coils on all my bikes.  This Ebay package with wires is a pretty good deal.  You'll have to either make an adapter or add 1 new mounting hole to each side of frame, as the spacing for mounting is not the same as stock.  Included wires are non suppression, wire core type without a resistor in plug end, so you'll want to switch to a resistor type plug.   Whatever brand or configuration you choose, be sure to use those with a 3 ohm primary resistance. 

http://r.ebay.com/Lbq4Nm
« Last Edit: July 26, 2017, 02:17:18 AM by vintage bikeworks »
1982 Yamaha XZ550 Vision
2002 Yamaha FZ1
1978 Honda CB400TII Hawk
2018 Yamaha FJR1300

QBS

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #4 on: July 19, 2017, 06:17:32 PM »
Vintage, what is the vdc output of your DC3-2 coils?

vintage bikeworks

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #5 on: July 19, 2017, 07:29:33 PM »
Vintage, what is the vdc output of your DC3-2 coils?

specs attached...
1982 Yamaha XZ550 Vision
2002 Yamaha FZ1
1978 Honda CB400TII Hawk
2018 Yamaha FJR1300

pinholenz

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #6 on: July 21, 2017, 10:52:21 PM »
I have found that Iridium plugs as part of an overall upgrade of spark plug leads and caps has really improved my starting. I have used NGK DR9EIX plugs. Apparently these run slightly "hotter" than the regular plugs, resist corrosion and are less likely to foul.
I haven't needed to change or adjust a plug in 4 seasons.
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Prophet Of Doom

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #7 on: July 22, 2017, 08:54:10 AM »
+1 for the Iridiums


artbone

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #8 on: July 24, 2017, 07:31:18 AM »
Installed Dynatek miniature series DC3-2 coils and haven't looked back.  Stock coils were always known to be marginal on 70's and 80's bikes.  A much stronger spark equates to easier starting, smoother idle and running.  I've made it a practice to replace the original coils on all my bikes.  This Ebay package with wires is a pretty good deal.  You'll have to either make an adapter or add 1 new mounting hole to each side of frame, as the spacing for mounting is not the same as stock.  Included wires are non suppression, wire core type so you'll continue to use resistor plugs - Same as stock.  Whatever brand or configuration you choose, be sure to use those with a 3 ohm primary resistance. 

http://r.ebay.com/Lbq4Nm
Would you explain about the 3 ohm resistance? Does the stock wiring have a resistor or is that something you have to add and, if so, where can you buy the resistor?
Art Bone

'83 Yamaha Vision in the Classic Black and Gold  Running
'82 Yamaha Vision Running
'74 Norton Fastback - Colorado Norton Works #26  Running
'73 Norton Interstate  Running
'75 Triumph T 160  Running
'62 Harley Davidson Vintage Racer
'61 Sears Puch  Running
'15 Triumph Scrambler
'17 Honda Africa Twin
94 Kawasaki KLR 650

turbosteve84

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #9 on: July 24, 2017, 06:56:23 PM »
No add ons. I believe he's referring to the ohm rating of the coils themselves.

Steve
« Last Edit: July 25, 2017, 07:56:54 PM by turbosteve84 »
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artbone

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #10 on: July 25, 2017, 07:22:28 AM »
Yes, after rereading I see you're right.
Art Bone

'83 Yamaha Vision in the Classic Black and Gold  Running
'82 Yamaha Vision Running
'74 Norton Fastback - Colorado Norton Works #26  Running
'73 Norton Interstate  Running
'75 Triumph T 160  Running
'62 Harley Davidson Vintage Racer
'61 Sears Puch  Running
'15 Triumph Scrambler
'17 Honda Africa Twin
94 Kawasaki KLR 650

vintage bikeworks

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #11 on: July 26, 2017, 02:23:17 AM »
No add ons. I believe he's referring to the ohm rating of the coils themselves.

Steve

Sorry Art.  Was away from home.  Yes, the 3 ohm is the primary resistance of coil.  To correct an earlier statement I made concerning the stock wires and plugs -  The Ebay replacement wires have a wire core and the plug end is without a resistor, (stock wire ends have a 5k resistor built in) so you should switch to a resistor type plug.  The NGK iridium resistor type replacement for the stock D8EA is a DR8EIX.  See attached.


« Last Edit: July 28, 2017, 02:58:46 AM by vintage bikeworks »
1982 Yamaha XZ550 Vision
2002 Yamaha FZ1
1978 Honda CB400TII Hawk
2018 Yamaha FJR1300

cvincer

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #12 on: July 26, 2017, 08:51:03 AM »


Wire ...... spark plug cap ......  spark plug.

How can you tell if the      spark plug CAP     is the resistor type?

vintage bikeworks

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Re: Spark Plug gap of .024 inch = big improvement starting
« Reply #13 on: July 26, 2017, 04:52:51 PM »


Wire ...... spark plug cap ......  spark plug.

How can you tell if the      spark plug CAP     is the resistor type?

They typically look like this and are usually replaceable. (because they do fail)  5k ohm resistor is common. You can unscrew them from the wire (entire cap assy.) or disassemble to check resistor.  Pics attached.

.
« Last Edit: July 28, 2017, 02:58:16 AM by vintage bikeworks »
1982 Yamaha XZ550 Vision
2002 Yamaha FZ1
1978 Honda CB400TII Hawk
2018 Yamaha FJR1300