Eric, Rich, Check out this plug.

[Masterphil]

This plug (BR9ES) was pulled from my 125SX running 32:1 PumpSluge mixed with Klotz supertechniplate. Jetting 1.5 out 45 pilot, 1469g needle clip position 2, 192 main. Temperature 67F, Relative Humidity 60%, Baro 30.12,Dewpoint 53F, AltitudeDensity 358ft. The dirt was a mixtue, some spots sandy, some loamy, not much hard pack. The color of the insulator is a little lighter than the picture shows, this leads me to believe that the heat range is spot on for the riding conditions today. The thick ring at the base of the insulator (2mm thick) leads me to believe that the main jet is way too rich.

This leaves me with a few questions:
How thick should the mixture ring at the base be? I have previously heard that it should be about as thick as your thumbnail, how small is too small?
How much leaner sould I be able to go on the main, down to a 190, 188, lower??
The rest of the carb circuits feel the same as the main jet, so does it also follow that I should be able to raise the clip at least one spot and lower the pilot one spot and still be safe???
I know race fuel would be a wise addition, but this is what I've got to work with now, maybe race fuel next time.

 

[ellandoh]

im no expert by any means, and would wait for more qualified responses, but i can tell you that a needle position will make no difference on a plug chop but a smaller pilot will slightly reduce the total flow of fuel in a plug chop which could reduce that ring for ya

edit; is that a plug chop or how long did you ride on it??
sorry didnt see the text before the pic til now..... :bang:

 

[steve125]

Heres a link with useful info.

On my 144, the fuel ring is usually jetted in the 1-2mm range. Keep a close eye on the timing(center electrode), when jetting this close to the edge on pump fuel.

http://www.tsrsoftware.com/sparkplug.htm

 

[bclapham]

to my knowledge, unless you put a fresh plug in and do a wide open throttle chop then looking at the plug after regular riding is futile (given all of the different circuits).

my advice is you run the thing leaner and leaner until it pings :yikes: then go back 1 size.

FWIW- i tried the straight section 1469 needles on my RM144 on both the 36 and 38mm PWK and it always pinged at 1/4 throttle- only going to the KTM nozi needles cured it.

Erics advice would probably be go ask Rich, LOL!

i always ran an 8.

 

[Rich Rohrich]

You are at least in the ballpark, so if it runs good as is then leave it alone. It's really important to keep in mind that you can not safely tune razor sharp on pump fuel.

If you want all your bike is capable of, you'll have to buy some decent fuel and tune for it. Otherwise you'd be wise to err on the conservative side while jetting.

No one ever broke an engine from jetting it a little too rich. ;)

 

[Masterphil]

Rich, for the sake of learning, assume that I am using race fuel, although I won't attempt to jet any sharper than I currently am using the pumpsludge. I understand the benifits of using a good race fuel. Each batch is chemically identical, it has the benefit of being stored in a sealed can untill I open it. I would be running U2, but at the time, I didn't have the $$$ lying around to spend on it.

 

[Rich Rohrich]

If this were a PROPER plug chop on a new plug running clean fuel, then it would likely be pretty rich and possibly running at too low a plug temp (too cold a heat range plug). You have to start by getting the plug heat range correct first, then you can move forward to reading the mixture on the plug, and then as Steve pointed out the more subtle aspects like ignition timing, etc.

You have to keep in mind that plug reading is too a large extent learning how your oil and fuel color the plug, how your riding conditions change the look of the plug, etc. You have to learn YOUR setup to really do a good job at this.

The best advice I can offer if you really want to learn this stuff, is to buy a lot of plugs, a notebook, and something to accurately read temperature and barometric pressure. Then look at as many plugs as you can from your bike, under as many different conditions as possible and take lots and lots of notes. Reading plugs is a lot like learning to ride well, it's a cumulative effort over time. ;)

 

[Masterphil]

My next purchase is going to be a quality plug viewer. Thanks alot, Rich.

bclapham, Leaning to the point of pinging sounds like a one way ticket to a blown motor, that's a little to scary for me!

 

[steve125]

The VP U-2 is an excellent power making fuel! But when extra detonation protection is needed, like in the case of my 144. The VP MR-8 is an excellent choice, it makes the same power as the U-2 on the dyno tests we performed.

Last but not least is the VP C-12, its not the power maker like the others, but it will allow you to tune for more power with the needed protection over pump. And is very cost effective to run. :cool:

 

[elf]

I wouldn't go any leaner than 190 main with the 1469G, it needs a bigger main than some of the other ktm needles.