TOPIC:

Here we go again... I don't think this carb has ever been right. I am fouling NGK B6ES and B5ES plugs in under 100 miles. I have an electronic ignition, 2 into 1 pipe without the baffle, and UNI foam filters *without* oil. If anything I should be LEAN! with the stock carb setting?!? The confusing thing is that I live in an area where I NEVER use full throttle, not even close.. so putting around town I'm fouling plugs with the c-clip in the middle position. I got these carbs from wiredgeorge and had smithgpz put in a larger 145 mainjet, but I'm not getting into full throttle so I would assume that the mainjet isn't much of a factor. Another confusing thing is that moving the c-clip higher (leaner) made it sputter like it wasn't getting enough fuel. What in the heck is going on? I am very confused.

Not enough spark? Need a hotter plug (B4ES)??

Post edited by: shawntmartin, at: 2007/03/22 09:04

Post edited by: shawntmartin, at: 2007/03/22 09:06

Not familier with 750 twin but isn't 5es or 6es plugs way too cold? Especially stop and go around town?

If your plugs are dry and carboned... I had something similar. For me the solution was new coils. There was spark but apparently not nearly enough.

Hope this helps. Best of success!

shawntmartin wrote:

Here we go again... I don't think this carb has ever been right. I am fouling NGK B6ES and B5ES plugs in under 100 miles. I have an electronic ignition, 2 into 1 pipe without the baffle, and UNI foam filters *without* oil. If anything I should be LEAN! with the stock carb setting?!? The confusing thing is that I live in an area where I NEVER use full throttle, not even close.. so putting around town I'm fouling plugs with the c-clip in the middle position. I got these carbs from wiredgeorge and had smithgpz put in a larger 145 mainjet, but I'm not getting into full throttle so I would assume that the mainjet isn't much of a factor. Another confusing thing is that moving the c-clip higher (leaner) made it sputter like it wasn't getting enough fuel. What in the heck is going on? I am very confused.

Not enough spark? Need a hotter plug (B4ES)??

First, Bluemeanie, it's the other way around.
Shawn! Holy crap, the 5 is WAY to hot a plug to run. Even the 6 is, I know. You should be running 8.
Have you done the coil-power relay mod? DO THAT FIRST if not. This will get you a nice full spark for you to start with a good baseline.
I had the exact same problem with BOTH of my 750 twins. In the end, it turned out to be a combination of problems: weak spark (so I did the coil-mod), bad coil (so I got a dyna), improper pilot adjustments (because I was trying to compensate for the bad coil and spark).
Also, you didn't mention how many turns-out your pilot screws are - this is very relevant.
And one clarification, you said it shouldn't be getting to the main jest because you're not full throttle; I would argue that you start to open the main jets at about 1/4 to 1/3 throttle, so it *may* matter.

The pilots are 1.5 to 1.75 turns out. I think its a spark thing too. I just use B6ES because thats what the NGK website and the sticker on the bottom of my seat say to use. Can you help me with this coil power rely mod? And where can I get this dyna coil? Did you buy the Dyna coil AND do the mod in addition? I could use some help with this....

I have a Newtronic Ignition if that makes any difference. And do you think a 145 jet is too big of a jump with this set up?

Post edited by: shawntmartin, at: 2007/03/23 14:30

Click HERE ....scroll to bottom. 1st document in left column. Open and print....read carefully. Assemble tools, execute instructions. One coil relay mod......

I think the stock main jet is 125 or 126 ? My service manual is out in the garage ,, 145 seems real big .. Both of my twins had so-so coils on them I replaced them with Accel Coils and then dont forget the spark plug caps as both bikes had problems with them , I replaced those also .. ,,,Z1enterprises.com is a good source for parts also ebay

Post edited by: Shoe48, at: 2007/03/23 17:09

shawntmartin wrote:

The pilots are 1.5 to 1.75 turns out. I think its a spark thing too. I just use B6ES because thats what the NGK website and the sticker on the bottom of my seat say to use. Can you help me with this coil power rely mod? And where can I get this dyna coil? Did you buy the Dyna coil AND do the mod in addition? I could use some help with this....

I have a Newtronic Ignition if that makes any difference

Heck yeah, I'll help!

First things first, replies to the points in the post:
- 1 1/2 turns out is good, in fact it will be likely lean after you do the mods.
- The B6ES *was* listed as original equipment on the '78+ twins. Oddly enough, it is contradicted in the service manual. I posted a whole bunch on this in the old forum archive. To the point, get and use B8ES, especially after you do the coil and coil-power mods.
- You can get a coil in many places, I got mine at z1enterprises.com. *If* you should go with a Dyna, and since you have a Newtronic, you'll need one of the Dyna Dual Output 3.0 Ohm Coils DC1-1 . It's $65+, which is not bad.
- I did the coil-power mod FIRST while troubleshooting my poor running twin. It breathed so much life into the old girl that I thought all my problems were over (I've since gone over the harness and cleaned up and re-soldered much of the wiring). However, once the coil had good power, the "stammering" problem that was mild before was more bothersome. Turned out to be a mis-firing stock coil. You know what *should* have been a clue to me? While setting the timing, I noticed that the light didn't always blink at every revolution. I thought, "that's odd", but I never put it together in my head.

So, to get the ball rolling, buy these things:
12VDC BOSCH RELAY SPDT 30A
12VDC 5-PIN RELAY SOCKET
...and of course, solder and iron, heat-shrink wrap for wiring connections, and wire cutter/stripper, etc...

Once those arrive, we'll pick it up and I'll give you color-coded wire-to-wire connections and some tips. Of course, you *might* want to wait on the new coil to see if the problem is just the power... but that's up to you...

Let's get that thang feexed!



EDIT: I forgot to mention, you also need an inline fuse holder... make sure you give a good look at the "coil-power mod" doc and make sure I didn't niss anything...

Post edited by: Biquetoast, at: 2007/03/23 21:46

shawntmartin wrote:

The pilots are 1.5 to 1.75 turns out. I think its a spark thing too. I just use B6ES because thats what the NGK website and the sticker on the bottom of my seat say to use. Can you help me with this coil power rely mod? And where can I get this dyna coil? Did you buy the Dyna coil AND do the mod in addition? I could use some help with this....

I have a Newtronic Ignition if that makes any difference. And do you think a 145 jet is too big of a jump with this set up?<br><br>Post edited by: shawntmartin, at: 2007/03/23 14:30

I did the coil power mod, and before I did it, my spark reminded me of a cigarette flipped off the Golden Gate Bridge, just before it hit the water. Now it looks like the aurora borealis on steroids, or maybe something from the Frankenstein movie!

125 is the stock size jet for the 76-79 (probably the 80 also, but I don't remember), and 145 does sound huge.
But I know SmithGPz, and he does know what he's doing, and he has (or at least had) a dynamite KZ750 twin.

So if he said a 145 will work for you, then I'm not going to argue

Does anyone know if this coil mod is specific to KZ's or can it be applied fairly easily to other bikes?

beardking wrote:

Does anyone know if this coil mod is specific to KZ's or can it be applied fairly easily to other bikes?

I would think it would apply to any bike with a coil...


Gotta be careful here though.

Remember that the idea of the coil mod is to gain you a slight advantage in power to the coil, by feeding power straight from the source instead of going all the way through the harness.

On bikes where there is a considerable loss of power, it would be worthwhile to add an additional step to the process: spend some time to find out *why*.

It is possible that there are failing or corroded connections somewhere inline that should still be addressed! It might save you from having to replace a stator of regulator...

Remember, in the mod, the old power wire is still the trigger for the relay, so it still needs to be...at least... reliable, if not strong.

My point is, do the mod anyway, but you might really want to know *why* you needed it...