# 4 sparking wierd...

Hi I have a 1983 kz750 ltd h4 its having a wierd spark issue. I will start the bike and pull off each wire to each cylinder. I pull#1 stumbles and dies, same with two and three. Now number 4 I do it and it doesn't even stumble but if I get it close enough to the plug you can hear the spark and it sounds healthy but if I push it fully on it stops running on all four. And the exhaust is nuke warm 1-3 are too hot to touch. What should I check and how? Thanks ill try to add my video of it

Replace that spark plug cap and see it it runs properly. Ed

Ignition Coils And Sparkplug Wire Choices

What came with the bike, were ignition coils that even when new were marginal, add years of cooking under the tank in the stop and go traffic, and the coils will probably fail when hot.

Replacement coils can be bought at www.z1enterprises.com I believe “Emgo” is the brand. They also carry the popular Dyna 2.2 and 3 ohm coils, along with replacement sparkplug wires.

Now, you have a choice on sparkplug wires:

1.Copper plug wires with no supression caps (the best choice, but will produce audio noise on Radio’s and TV’s). Not only do the copper core wires deliver better spark, they will also deliver a much longer lifespan - carbon core wires are prone to erratic spark delivery and early breakdown, & short lifespan.

2.Copper plug wires with supression caps (a built in 5000 ohm resistor, that can sometimes fail, like what came with the bike). These should be checked with a multimeter now and then, as heat can cause them to become intermittent.

3.Copper plug wires with no supression caps, but using resistor plugs(the “R” in the plug number).

4.Supression plug wires with no supression caps.

NEVER use resistor plugs combined with supression caps along with supression plug wires, as now there will be possibly three (3) sources of resistance in the secondary windings of the ignition coils, greatly reducing the spark energy.

Another choice is the Accel 3 ohm coils, with a similar, primary(small wire)electrical connection, using ring terminals as the Dyna ignition coils do. Whatever brand of coil you go with, make sure the primary wires will clear the mounting hardware, as the spacers come close, possibly blowing a fuse. Some riders have replaced the metal spacers with non conductive Nylon spacers, reducing the chance of an electrical problem.

7mm sparkplug wires will fit the stock ignition coils(if they have replaceable wires, indicated by screw off caps on the coils with ridges). The sparkplug wires fit into a port with a brass ”Stinger” that goes into the sparkplug wire or lead(the Brit’s. Canadians, and other countries call the sparkplug wires (“High Tension Leads”).

I would replace all the caps and spark plugs. The reason it runs better when you pull it off the plug like that is, the spark has to arch it's way to the plug and once it makes it to the plug it creates a hotter spark so the plug has a stronger spark. I usually get this when the plugs are fouled or the caps need replacing.

the spark plug caps are inexpensive and easy to find 2-3 dollars a piece if not less and they twist onto the wire with a little screw inside the cap.

Ok so I switched caps around 1 to 4 same result it is sparking just not enough. I'm thinking its the coils I think they are the originals. They are a week old ngk bs7e plugs.

you are using the wrong ones , you should get the b8es ngk spark plugs.

That's what I had but now have 7s cause they run hotter

The B7ES plugs should work perfectly for street riding. The colder B8ES plugs would be more appropriate for track use. Ed

andyvr4 wrote: That's what I had but now have 7s cause they run hotter

That's hotter as in "holds more heat in the clinder" Andy. It's got nothing to do with the spark

1 & 4 are on the same coil. If 1 fires, it's probably not the coil failing. Trim the end of 4 plug wire about 1/4 inch and make sure to screw the cap on tight. See if that cures it for you. COST = Zero

B7ES are fine for street riding.

And quit doing that with the plug wire. You can actually hole a piston from that.

I have the 7's on there also but I think I will clean the 8's and use them simply because the heat range is an unknown at this point.
I have been hitting a dead spot after big revs on occasion.

donthaveakawman wrote: I have the 7's on there also but I think I will clean the 8's and use them simply because the heat range is an unknown at this point.
I have been hitting a dead spot after big revs on occasion.

If your bike runs i would just leave it alone before you F it up. Just ride the poor old kaw.