Old Ignition Coils on a 1981 GPZ 1100 - Just Toss

Hi:

I recently purchased a 1981 GPZ 1100 that is pretty much bone stock and in great condition for its age. However, it does not run right, stumbling a lot before it hits around 4K RPM then is all right for the most part.

I figure that with bike being owned (till I bought it last week) by its original owner, its low mileage, and good care that it saw over the years, I should be able to get it up and running with all of its stock components.

I've begun to go through it, and it looks to be a winter-time project. With the factory service manual, I've started to do static electical checks of various components. I was reading on a KZ1300 site regarding that after purchasing one of them that is 30 years or so old, to toss the stock ignition coils. The owner of the site says this is a "MUST DO if you want the bike to run as good as it should." He mentions a brand of coils called Nology as a replacement coil. He also mentions somewhere else on his site, when he buys these bikes, he doesn't even bother to check if the old ignition coils are okay, that he just tosses them and puts on the Nologys.

According to the factory service manual that I'm using to do static electrical checks on various electrical components, there's a couple of low-level checks for the ignition coil, but there may be potential issues with the coils, that cannot be found with these kinds of checks. There also is some "arcing" distance check that utilizes a special diagnostic tool, a Kawasaki Electrotester, but who would have one of those handy? Seems like I could just pull the spark plugs, ground its threads to the engine case, and crank the engine, to see the condition of the spark. Would this be safe to do considering the electronic ignition components?

Sidebar: when I was pulling the spark plug caps loose to check the condition of the plugs, the #4 cap came off right off its lead. Upon inspection, I'm thinking that there was not all that good of a connection between the cap and lead to begin with. According to the factory service manual in the ignition coils' inspection section, to replace the ignition coil "if either spark plug lead shows visible damage." This is the case for me. However, I didn't see any evidence of arcing and burning on the cap and lead end, or where it screws into the core of the spark plug lead. However, the end of the lead is mangled enough and its length insufficient to trim back to a good area, that I'll probably at least replace this lead with a new one. Or maybe I should replace them all? Anyone have ideas about what type and size of bulk spark wire lead to buy as a replacement for the stock leads?

Does anyone have any advice for checking, or just plain replacing the ignition coils, and the spark plug leads?

I'm not a cheap a**, but I don't wish to needlessly throw money into areas of the bike's refurbishment that could be better used in other fruitful, logical areas.

Thanks in advance for your feedback.

Marty

just because something is old doesnt automatically mean it needs replacing,check it out first

The KZ1300 is a six cylinder using 3 coils. On that bike space is an issue, so small coils (Nology) are a consideration. On the inline-fours, there is plenty of space for a large conventional coil. Otto will know better, but I'm pretty sure your bike has electronic ignition. In that case you want the 2.2-ohm Dyna coils.

On one of my bikes, I'm using 30 year old coils and it runs great. But I don't take the bike on far away trips because I've been stranded by dead coils before.

If your coils passed the servic manual tests they're probably ok. I could be wrong, but I believe if the coils were bad the stumbling you describe would happen even worse at higher RPMs, where there is more demand, rather than only at the lower RPMs. Ed

Actually, a misfire is a lot more noticable at lower RPMs. The engine vibrates more and sounds worse. Revving up usually masks the effects of a missing cylinder.

When my coils were dying, I rode a few miles on just one coil. The more revs I had, the less I noticed the misfire. Then the only indication was a lack of power.

loudhvx wrote:

The KZ1300 is a six cylinder using 3 coils. On that bike space is an issue, so small coils (Nology) are a consideration. On the inline-fours, there is plenty of space for a large conventional coil. Otto will know better, but I'm pretty sure your bike has electronic ignition. In that case you want the 2.2-ohm Dyna coils.

On one of my bikes, I'm using 30 year old coils and it runs great. But I don't take the bike on far away trips because I've been stranded by dead coils before.

This is correct, the 1300 has a 3 Ohm ignition system while the GPz has a 2.2 Ohm system. You would cook the Nology coils on the GPz. I run a set of Dyna 2.2 Ohm (gray0 coils on my GPz and I love them. An 81 GPz1100 had some issues and you will have to go threw it carefully. The biggest problems this bike had was with overheating Injectors. This is why Kawasaki did away with that system and changed it in 82.

GPZ1100_Rider wrote:

Hi:

I recently purchased a 1981 GPZ 1100 that is pretty much bone stock and in great condition for its age. However, it does not run right, stumbling a lot before it hits around 4K RPM then is all right for the most part....

Are oem injectors still being used?

Edit --- just noticed your other thread:

GPZ1100_Rider
ECU for 1981 GPZ 1100 EFI - Any Way to Check it Out

Am thinking some owners have opted to replace injector system with carbs.

Good Fortune!

Coils are actually flyback high voltage transformers and I don't trust old ones either (HV transformers don't age well)..... and also because of all the time I wasted fooling with carb jets when a weak coil was the real cause of my fouled spark plugs. When my coil failed altogether I bought a "good used one" which ran but didn't spark hot enough to keep the spark plugs clean.

PLUMMEN wrote:

just because something is old doesnt automatically mean it needs replacing,check it out first

The problem with coils is there is no reliable way to static test them. The primary failure mode is "arc down" where the high voltage arcs across to another point. A marginal coil will typically only do it under full load operation and usually only after they heat up.