2 and 3 intermittently dying

The coils appear to be original but the wires look new. The thing is.. every time I find a dead cylinder I pull the plug wire off it and hook up an extra spark plug and ground it to the engine and it is always firing perfectly. Ive never once seen a plug not fire on this bike.

I spent the last hour trying to pinpoint the vacuum leak without much luck.. If i sprayed a big wide blast of carb cleaner it would bog down, but if i tried spraying it on very specific spots i couldnt seem to get it to bog at all. Either way the only thing it could be is bad carb boots/leaky pcv valve tubing. So I guess I'll replace those..

Im also going to go through the electrical system and make sure the coils get 12v.

Another thing I noticed is the warmer the bike gets, the better it runs. #3 header is still cooler than the rest though.

If you're still using the sparkplug caps, one or more may be failing, as they contain a 5000 ohm resistor for RFI suppression(when the plug fires, the electrical noise generated is RFI).

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 ignition 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 understand MFolks, but are you really convinced that my problem is with the spark? Because Ive checked every cylinder countless times while the bike is running and it has always produced a good strong spark that can easily jump a ~.5" gap from the plug to the engine block. It would be very frustrating to dump ~$200 (on a $500 bike) into new coils and wires just to find out that the old ones worked fine..

Just an update, I installed the new carb boots today and they made a huge difference. The bike will happily idle without choke now and the throttle is extremely responsive. Also, all 4 cylinders seem to be firing well. It still has a moderate backfiring issue but im thinking I just didnt clean the carbs well enough. Its finally at the point where its driveable so im gonna run a full can of seafoam through it and hopefully that will help.

Thanks guys!

well thats good to hear