Hotter plugs-- B7ES?

KZ Riders,
I'm thinking about using hotter plugs on my '78 KZ1000, and I wanted to see what you all think, what your experiences have been.

Like I said, my bike is a '78 1000. I've been running standard B8ES NGK plugs. I'm thinking about going a step hotter-- to NGK B7ES.

It still has points, standard coils. The timing is slightly advanced.

I have done the Wired George mod, running a hot line straight to the coils from the battery.

I have jetted up the carbs, and they have pods on them. The air mixture screw is one full turn out on each carb (it pops if I lean it out beyond this) .

The carburetors themselves are a rack of VM28s (with accelerator pump) off of a '79 KZ1000E1 (shaft).

The exhaust is a Delkevik four into one, baffle out.

The bike screams-- BUT it gets about 30 mpg, and the plugs are always soot black. It's not oil, it is fuel. It also smells pretty rich on idle.

So, I was thinking that there clearly is further combustion of fuel that could happen, but isn't happening-- due to all these factors (i.e. jetting, no baffle, older points system).

Could I safely obtain greater fuel efficiency by running the hotter NGK B7ES plugs?

Other factors: I live in southern Arizona, and it is hot. When I get out on the highway, I hammer on the throttle, and tend to live somewhere around 90 mph.

What do you all think?

I wouldn't go hotter to burn off excess fuel.
It sounds like you have several issues on different fuel circuits.
You need to correct the jetting and possibly resolve float height and flooding problems.
I would also junk the points and fit a Dyna 'S'.
What size main jet do you have fitted and have you installed air corrector jets for the pods.
You should be getting easily over 40 mpg .

You say you re-jetted. What did you replace?

Some things to check...

Float level, choke circuit and plungers, needles and needle jets, fuel/air screw settings.

One other thing you may want to try is switching from NGK plugs to Denso plugs. The Denso (sometimes marked ND or NipponDenso) plugs that are equivalent to the NGK B8ES plugs are the W24ES-U plugs. On my Kz650-C1 I switched from NGK to Denso and found the Denso to work better and never foul. It may or may not help you, but considering how inexpensive and easy it is it might be worth a try. Ed

Hardrock Miner, thanks for these thoughts.

To answer your question: I re-jetted the pilot to 22.5, and the main to 120. Also raised the needles a bit (I think to the standard third clip notch people recommend for pods and 4-1 exhaust).

Went back and forth adjusting all of these things years ago, until I got the performance just right. Been running this jet configuration for years, and don't think it is the issue.

I suspected the richness was in the idle/pilot circuit, so I tried playing with the air mixture screws a bit (I've always run these at one turn out). If I leaned it out, it started popping, so I'm sure the issue isn't that.

I've been through the choke circuit a few times. It's good.

Why would the float level affect this? I haven't had any issues with starving or overflowing.

Zed, thanks for these thoughts.

I'm running 120 main jets. 22.5 pilots.

What are air corrector jets for the pods?

When you did the Dyna S, did you have to replace the coils, or run stock?

Also, why wouldn't you run the hotter plugs? Seems like they'd burn more fuel and it would be the cheapest fix-- right?

Dont run hotter plugs . Especially in AZ.
Dave

Wow, I have a 1978 1000 and no where near that rich on the jets. My bike sounds just like yours abeit dyna s ignition. I have 28mm with acceleration pump. I’m on stock jetting and running great.

Thanks-- that's interesting. Can you tell me what kind of exhaust/baffle and air box/pods you've got, and what your jet sizes are?

Vance and Hines 4-1 with untouch baffle, APE pods, 17.5 pilots, 115 mains. Dyna S ignition. I installed idle air correctors that a member here offers. They compensate for higher air flow caused by pods. Simple mod that works.

Mikaw, thanks very much. I'm thinking I may need to revisit jetting, then.

I jetted up as far as I did, because anything less than this had serious preignition with my pipes and pods. I do not have (and have never heard of) idle air correctors, and the preignition I was experiencing seemed to be primarily in the idle jet range.

What do these idle air correctors do, how do they work?

Also, I did a Google search for Vance and Hines untouch baffle, but didn't find anything? What is that? Just trying to get a full sense of how your bike is set up, so I can compare it with mine while trying to figure this out.

Contact Zed1015 direct.
He is the member who markets and sells the air correctors
He can answer all your questions on them
Dave