White spark plug ceramics?

Why are the inner ceramics of my spark plugs white?

I know they are supposed to be tan.

Btw, I checked them after riding it for 5-10 minutes, NOT after the bike sat idling.

Would it be running too lean or too rich? I actually adjusted the pilot screws clockwise(lean right?) to try to solve low rpm bogging and performance. I think it helped... Now they are all approximately 2 turns out +/- a few degrees on my 1993 XJ600. I had them at 2.5 turns out like someone else suggest and ran like that for a while but my engine wasn't idling perfectly.

 

2 turns is probably too lean, start with them all at 2&3/4 turns from bottom, give the bike a good run, let cool a bit, pull the plugs, can you post a good close up picture of the plugs, so we can all have a good squiz at them?

 

Don't be running too long if the Plugs are that clean!
You are better off having the Bike be Rich
Lean can cook you out of an engine before you even know what hit you.

The bike LIKES to run lean.
The bike is fun to run lean.
There is explosive power and performance.
Meanwhile the lean burn is heating-up a situation that can't possibly be air-cooled.
Somethings got to give.

Don't get caught that way.
ADD some Richness to that bike and KEEP adding it until you see some coloration on the Plugs.

Until you know for sure that you aren't in the Critical Lean condition ... presume that you are damaging the engine and act accordingly.

If you don't know what to do ...
Check the Plugs time and again.

Keep turning the Pilot Mixture Screws OUT the width of a Nickel until you have achieved coloration on the Plugs.

 

Why would the engine run more smoothly and transition from idle to the mid and high rpms better?

What else can I adjust to make my bike idle better?

There is and adjustment knob in the middle of the carburetors that I believe is called the throttle stop. When I adjust that, the idle rpms go up like 200 rpms and then it idles ok. But when I get on the gas and the release it, the rpms stick at 2000 for a few seconds...

 

There seems to be 9 different ways to set-up the pilot jets on our bikes:

1) Initial set-up- - where the "book" says 2 3/4 out or so.
2) The factory gas analyzer, that nobody has. . .
3) The $50 colortune plug
4) Reading the plugs with multiple tests and tweaks.
5) ear method- - lean a CYL until it stumbles, then add 1/2 turn, or so
6) Manifold vac method- - tweak a CYL for best vacuum reading. You would need to combine the 4 VAC ports on our bikes.
7) RPM method- - tweak for max RPM and smoothness, similar to ear method.
8) Exhaust pipe temp reading- - un-tested method requiring a heat gauge. Max heat = max efficiency. Same heat = same set-up. More work needs to be done on this one.
9) A RickOMatic idea of finding a CYL with a good looking plug, that carb is set-up right. Drop a glass fuse on the Pilot screw, draw a line on the fuse, use that to set-up the other 3 carbs, then final tweaks with plug reads.

Soon, I will combine my 4 tube Manometer, with a VAC gauge at the bottom of the rig, giving a perfectly steady reading, with the Colortune method and the RPM method at the same time. Then do plug reads.

Here's a graph of ideal combustion efficiency:

I think we are shooting for richer than stochiometric on our bikes.

 

thanks for the info on the different methods of tuning as well as that a lean situation damages the engine.

I just got home from work and worked on the bike trying to turn the idle screws out 1/4 of a turn at a time and then running it for ten minutes. I got to like 4 turns out I think and nothing has changed. They are still white.

do they affect top end performance?

because it feels like there is a lack of performance but it might be in my head...

 

If you are at 4 Turns Out ... somethings not right!

You have an obstruction(s) in the Pilot Circuit somewhere.
Clogged Pilot FUEL Jet
Clogged Pilot Mixture Screw Cavity
Obstructed Pilot AIR~FUEL Passage(s)
Something?

Maybe even the wrong Pilot Jets.
What have you done Carb Cleaning wise?

 

I have taken them apart completely ad let the brass pieces sit in carb cleaner solution. then I sprayed the cleaner through the passages and then with compressed air. The bike idles great and it seems to run perfect.

I recently readjusted the float levels...maybe i did something wrong?

 

You'll have to test for air leaks.

Unless you are running Pods ... are you?

Then, you need to re-jet and experiment.

 

are pods the high flow air filters? if so then no I am not running pods.

Where could air leaks come from?

would the float level have anything to do with my lean situation?

 

i have an 81 650,that i saved.i have done the the lean condition dance.if the adjustment makes no difference to the color of your plugs one of two things are happening,you have a clogged circuit or your sucking air.there is a enrichment circuit with a very small opening at the back of your bowls.it becomes clogged very easily and can cause such a condition.the inside of your carbs must be sterile.as far as air leaks-butterfly shaft seals and new carb boots and gaskets usually fix that.the lean condition rick spoke of is fatal to these bikes,patience and alot of adjusting and you will be on the road.

 

Look for any air leak.
Run the bike.
Probe around the Manifolds, Carbs, Boots and Gaskets with a Propane Torch that is turned on BUT not lighted. Just the gas on.

If there is an air leak ... the Idle will increase.
You can use Carb Cleaner but a backfire might cause a fire.

If there NO air leak ... the Carbs aren't doing it for you!
You have to find-out why the Mixtures are still Lean.

Try re-setting the Mixture Screws to 3-Full Turns Out.
Normally, 3 Turns out would be somewhehre close to where you want to be.

You night also try to put the word out to a Member near you who might have a Colortune Plug.
I have s suspicion that your Pilot Jets or Passages aren't cleaned-out well enough, yet.
You should be getting some gas up there if you have been doing some adjusting.

 

Thanks rick.

Yesterday I set the float levels to 7mm. They were at like 8 or 9mm.

So I fired the bike up today and there was a lot of backfire from the carbs. let it sit for like 2-3 min and then checked the plugs. They were all tan.

After it got warmed up there was no backfire and it ran smooth. So I rode it up and down my street and then let it sit for a few min. The spark plugs went back to the white color. Maybe a little tan.

 

Stay with it!
Keep adding some Pilot Mixture Richness until the Plugs get some color.

Look closely at the ones that have no color on them.
If the Center Ceramic shows signs of erosion or hairline fractures ... you are way too Lean and that can be harmful.

Just continue to Tweak.
Soon enough you'll get the desired results.
Shoot for a nice Tan or Light Brown on all of them.

 

thanks!

Ill keep tuning and then post up my settings and results.

 

Remember!
You're now "Fine-Tuning" with emphasis on the FINE!

Those Screws only need a nudge either way.
Just a hair.
The Mixtures you have right now do not look like they would be the root cause of any popping.

If you finish-up getting the Plugs showing that you are right-on and the Popping persists ... you are going to have to look into Tight Valves and Exhaust Leaks or some intermittent Ignition gremlin.

 

well there isn't any popping fom the carbs anymore. theres only a small backfire from the vacuum hose that is connected to the number 2 cylinder once in a while when the bike is warming up.

The bad thing is that it's still running lean. I've got the mixture screw up to 4 turns out testing in 1/4 increments. performance wise it runs great in the low rpms and throttle roll is smooth.

I think I am doing the actual procedure incorectly.

Basically I turn the bike on let it warm up for like 2 min and then ride it for like 5. Then let it sit for around 3 min and then check the plugs.

What do the mixture screw do exactly? They only control the air/fuel mixture at idle right? Then when I rev passed 2000rpm it goes to the jets?

 

Would you mind filling in the Signature Section with Thumbs about this Bike?
This thread is starting to get very confusing to me.

Signature Section:

Year - Model - Miles - Stock or Mod.

Now, I need to know what the heck we are dealing with. If you have done everything that can be done ... some PO might have stuck the wrong Carbs on the bike.

It happens.

650 and 750 Bikes share the same Carbs; but the 750 has different Jets all throughout. If you are trying to get the Bike tuned using a set of Carbs somebody bought off eBay that don't belong on that bike ... it ain't gonna work.

You'll have to check and see if you have the right Jets for that Bike and that the Jets are all in the right places.

Normally, the problem is running too Rich after a Carb Job.
How you could have no air leaks and have the Pilots out to 4 Turns and not have coloration or fouling is strange.

Do you know the sizes of the Jets you have in that bike?

 

I just updated my signature.

I'm on break at work right now but ill take the carbs apart and check as soon as I get home tonight.

Could you tell me if the mixture screws affect anything after 2000rpms?

 

Yes. They do. That's why Plug Chops are done as close to Wide Open as you can run.
Sure, the amount of Fuel still bleeding into the Full Throttle Mixture probably isn't much ... but, it completes the equation. Without the Supplemental Richness provided by the Pilot Jets ... the Air~Fuel Ratio would be different.

You'll see what a (my-nute) change in the Pilot Mixture Screw will do to the color of the Plugs when you begin an accurate round of Plug Chops.