Sooty Plugs

Hey guys,

I have been riding my kz650 around the neighborhood for the last week, rarely get passed 2.5k rpm. And I had the bike standing for maybe 5 min at a time while doing some fine tuning on the carb sync and fuel mix screws.

Would these conditions of ONLY low speed riding plus idling for potentially too long cause a plug to get all sooty? Assuming all else is fine like the fuel mixture, am I causing the plugs to foul quickly?

If not, and the plugs tend to get sooty, is it worth trying a hotter plug as the manual suggests? Currently running BR7ES and I guess I would try BR6ES?

Rev the engine up. 2500 rpm is lugging.

Don't go hotter than B7, and get rid of the BR plugs next time around. You don't need resistor plugs unless you got rid of the resistor caps on the plug wires.

lakshan wrote: "...........the plugs tend to get sooty, is it worth trying a hotter plug as the manual suggests? Currently running BR7ES and I guess I would try BR6ES?

Below are 4 step that should help. Keep in mind that I have owned my 1977 KZ650 since it was new (March, 1977) and have put more than 61,000 miles on it:

Step 1 - Throw away whatever manual said to install BR7ES or BR6ES plugs. That is totally bogus information and whatever manual said to install those plugs is NOT at all accurate.
Step 2 - Buy a Kawasaki Service Manual that covers your 1977 KZ650. The correct manual is Kawasaki Part Number 99924-1001-01.
Step 3 - Toss the plugs that are in the bike and install ND W22ES-U plugs (these will be labeled "ND", "Nippon Denso " or "Denso").
Step 4 - Stop riding the bike at such low rpm, and take it for a real ride that is a decent distance (more than 50 miles).
Ed

The manual I have:


Plug recommendation:


Advise on sooty Plugs:



This manual has been great so far and I think it aligns with all advise given by you so I don't want to throw it out
The manual recommends B8ES but as you've said before, B7ES runs better and the book has this recommendation as well. Problem is I do not have access to any Non - resistor plugs at all. I have called to get them sourced but they aren't stocked in any local store at all, not even online. IF they find them I would have to special order them. Based on researching, non-resistor plugs would be providing better spark but resistor plugs will also work. Because I do not have access to non-resistor plugs, what would you have me do?

That's why I am currently using BR7ES. And, as my screenshot shows above, the sooty plug condition suggests trying a hotter plug and I guess that would be BR6ES. The book doesn't specifically say to use this plug, I am just trying to figure out my next step.

As I said I had it sitting while doing carb sync so maybe that's why it is getting sooty. Carbs are synced great now so I can avoid this going forward.

I will recheck my ignition timing so I can rule it out.

What fuel do you guys use ? I thought I would use SHELL 91 because it has zero ethanol, but is it better to use a lower octane instead?

Your Haynes manual copied a mistake regarding spark plugs that was printed in the original version of the KZ650 manual (Kawasaki Shop Manual - Part Number 99931-539-01). That first manual, printed April 20, 1976, recommended NGK B8ES or ND W24ES spark plugs. Those spark plugs may have been ok for racing on the track, but they were too cold for street use. The later Kawasaki Service Manual (Part Number 99924-1001-01) that was printed April 11, 1977, corrected that error and specified NGK B7ES or ND W22ES-U spark plugs. Those are the appropriate spark plugs for the KZ650.

I do not understand why you say you cannot buy the correct plugs since they are readily available from a variety of sources. For example, Amazon offers them at:

www.amazon.com/Denso-W22ES-U-Traditional...k-Plug/dp/B0012Q5ZVK

Denso offers them at:

www.densoproducts.com/product.aspx?zpid=10699

If you enter “w22es-U spark plugs” in eBay you will find more than two dozen places offering them.

There really is no reason for you to install the wrong spark plugs in your KZ650, so again I highly recommend you buy the correct spark plugs.

I also still recommend you buy the correct Kawasaki Service Manual (Part Number 99924-1001-01) for your motorcycle and toss out the Haynes manual. If you plan to own the bike you really should own the manual that is specific to your exact model bike. It’s your bike, so do what you think is best, but I’ve owned my 1977 KZ650 for more than 43 years so I have more than a little experience with manuals.

Regarding fuel, I know others may recommend 91 octane, but on the recommendation of the dealer when I bought my bike I have always used 93 octane and have never experienced any knocking or other fuel related problems. Ed

I would love to do it if it was a reasonable option, everything else I have done has been OEM as much as possible.

In Canada, seems the options are limited.

Your Amazon link says it will take 1 month to ship to me in Canada.
That DENSO link produces a forbidden access error for me, and I can't even go through the site manually to find the plugs.

I am relying on the local stores here to source them somehow but it just seems like they aren't readily available.

Kawasaki dealership has also specifically told me that they only sell the resistor plugs and that they will be suitable for my application. I'm sure it's better to go non-resistor, I definitely agree with you to go OEM but you see I am a bit stuck.

My only question now is assuming I cannot change my plugs (stick to BR7ES), and assuming my fuel mix is right, what could potentially cause a sooty plug? I am trying to identify and fix what is under my control.

Noted on your advice about the manuals.

If you have resister caps and plugs you won't get a hot enough spark thus sooty plugs. You can see if they have Champion or some other plugs they can cross reference. BTW, old worn out valve guide seals can cause sooty plugs as well.
Steve

lakshan wrote: .................
My only question now is assuming I cannot change my plugs (stick to BR7ES), and assuming my fuel mix is right, what could potentially cause a sooty plug? I am trying to identify and fix what is under my control..........

Assuming you continue to use the wrong spark plugs you will very likely experience the same results. It seems odd that you are not open to the idea of simply ordering the correct plugs from one of the sources I gave because of the time element. It's hard for me to understand that not one of the 28 eBay sellers, most of which are willing to ship to Canada or other countries, is an option and that every one of them would take a very long time to ship to you. In any event, I wish you good luck with your project. Ed

Hi lakshan,

Go to your nearest Canadian tire store and have a look in the spark plug plug area. Particularly in the Sport/ATV part. This is where i find NGK B8ES plugs and you should be able to find B7ES. You wont find them on the Canadian tire website.. NGK with no R will work fine
I have never seen ND plugs in Canada

Ed,
The ND website is not available from Canada. Error 403 forbidden

Shipping ebay US has become exhorbitant and Amazon at times makes it difficult to use their US site in preference to their Canadian one which offers a smaller selection

Get the correct heat range plugs.
If you can not get non resistor plugs, replace the resistor in the boot with a conductor or get non resistor boots.
Start bike with old plugs and let warm up until it idles with no choke.
Shut off engine. Quickly replace plugs with new. Start engine, No choke or throttle, let idle 5-10 minutes. shut off and look at plugs. If sooty, pilot jet or adjuster screw too rich, choke on, clogged air filter.
Once it will idle without sooting plugs, test mid range. New plugs, Ride at a constant 70mph. Check plugs after 10 minutes.

lakshan wrote: I would love to do it if it was a reasonable option, everything else I have done has been OEM as much as possible.

In Canada, seems the options are limited.

Your Amazon link says it will take 1 month to ship to me in Canada.
That DENSO link produces a forbidden access error for me, and I can't even go through the site manually to find the plugs.

I am relying on the local stores here to source them somehow but it just seems like they aren't readily available.

Kawasaki dealership has also specifically told me that they only sell the resistor plugs and that they will be suitable for my application. I'm sure it's better to go non-resistor, I definitely agree with you to go OEM but you see I am a bit stuck.

My only question now is assuming I cannot change my plugs (stick to BR7ES), and assuming my fuel mix is right, what could potentially cause a sooty plug? I am trying to identify and fix what is under my control.

Noted on your advice about the manuals.

NGK B8ES are readily available at Lordco in Canada. The Denso plugs work better in my '77 KZ1000, so I ordered 2 dozen off of ebay and used the NGKs until they arrived.

Thanks everyone, I am waiting to hear back if they can source out B7ES plugs for me but I sat here calling every store possible and no one sells non-resistor plugs at all.

@BCScott Lordco is in BC and doesn't ship unfortunately.

Just thinking out loud, what is the main issue with using the BR7ES ? It's because it contains a 5k ohm resistor right? Do the stock plug caps have resistors ? How can I check if mine does?

If I swap them out with low resistance (1k ohm or less) caps, it should help right?

My first option and priority is to get B7ES plugs but I'm trying to figure out my next option that may work.