Colortuned XJ600 and ??

Today I have colortuned my xj600 1996 and finished with 4 1/2 turns out on each carb.

According Haynes manual factory setting is 2 turns out.
When I try to run on 2 1/2 idle is hunting and misfires on all cylinders. Spark plugs are light gray. Obviously lean...

When I unscrew 4 turns it runs steady but color is light light blue. On 4 1/2 turns color is as it should be according photos.
Yellow occurs over 5 and half turns.

On 2500 rpm and above up to red line, color of flame is correct blue. Also is correct on 2 1/2 turns of pilot screw.

I'm confused. What is going on with my carbs?

 

Sounds like they are clogged a bit. What air filter do you have? If a K&N then you are set right. If not then rich is always better than lean, so keep the 4 1/2 setting. Since it is running fairly well I would then add a can of Seafoam to a full tank and run the tank through. Then check with the colortune again and see if things are richer.

 

I’m iterating through the same problem on a 1985 XJ700 I just traded a friend for. It’s in pretty good shape but it wasn’t ridden or cared for in years. I had to take the carburetors off clean out the jets just to get it started. It ran but still very lean. I noted that the pilot screws were all out three and four turns and anything needing a screwdriver to turn was all boogered up so apparently my friend had some gorilla work on the bike.

Ultimately, the floats were really low (like 1/4” low!), as if the float valves were changed and not adjusted or adjusted completely wrong. My recommendation: check the basics first... clean jets, make sure it’s got the factory jet sizes, and check the float adjustments. A simple check to see if the tank flows gas is to just pull the fuel line off and swing the fuel selector to "prime" for a second (obviously not while the engine is hot and you'll need a rag or cup to catch the gas).

Again, check the basics first.

 

2 BlueMaxim:

She has got stock filter. New one...
Doesn't run fairly well, but superb now
I'dont know about clogged jets because all carbs require same setting i.e. 4 1/2 turns out...?
I'm so happy after colortuning and I can't stop to ride...
Don't laugh at me but what the hell is Seafoam?!
I guess it is some carb cleaning fuel aditive?

2 IllinoisMaxim:

My bike is completely stock regarding carbs, exhaust, electric...
Fuel levels are about (5 mm) and according to Haynes manual they should be 3-5mm. If levels were low shouldn't she run very lean on high rpm?
I have already checked PRI position priming and it is working well. I also tried to put some clear tube between tank and pump to see if fuel is flowing at "ON" position. All seems to be OK.

:?:

 

So everything runs perfect, it's just that the screws are turned out more than expected?

I'm inclined to say "if it aint broke, don't fix it".

Yes, if the floats are low and the screws are turned out to compensate, you will go lean at wide open throttle. Wide open throttle is different that high RPM because you can get high RPM with no load, such as in neutral, with the throttle only a fraction open. This does not truely test the main jets. You need to have it on a dynometer or take it down the highway to check it at wide open throttle.

I'm not trying to say that you did anything wrong (you may have check it at full throttle, I don't know). My point is that if you do go lean at full throttle and don't know it, the excessive heat caused by a lean condition for extended time periods (such as a long highway trip) may cause engine damage, or at the very least excessive wear.

SeaFoam is an engine treatment and is a refined petroleum product. It can be added to gas to remove water, stabilize the gas, and remove varnish. It can be added to crankcase oil to remove moisture. It will clean carburetors. It will grow hair and make you taller (just kiddin').

 

Oh sorry, I should have said:

"... this does not truely test the main jets which are dependent on the float levels for proper mixture levels and are less affected by the additional fuel provided by a richly set pilot circuit..."

"whew"

 

Yep I agree!!! Sorry about the Seafoam reference, you may not have that in Croatia. Basicly is just a carb cleaner that we use in the tank to mix with fuel.

 

Ok, I have done some Goooogling... :lol:
I don't think that we have importer over here for Seafoam. But, I am shore for STP products. What do you think about this? Same stuf?

http://www.stp.com/fuel_cfsc.html

Regarding this lean condition at full throttle... How can I test It? I know that throttle response is same as she was new.
I have colortuned only until red line in neutral.

I agree with IllinoisMaxim when he wrote "If It aint broke, don't fix It."
I just was wandering what could be wrong with my carbs or something else on fuel system... :?:

 

STP and SeaFoam same stuff? Maybe... but nothing replaces actually taking something apart and cleaning it. My primary use of SeaFoam/STP is gas stabilization for extended storage. But then again, why would you want to put a motorcycle in storage?!

Testing wide open throttle: (1) Install new or really clean spark plugs and put your plug socket, wrench, and torque wrench in your backpack. (2) Head immediatly out on the highway, no driving around town (if you have to install new plugs at a rest stop or highway off ramp, do that). (3) Drive at highway speeds, no drafting trucks, wear a big jacket, whatever really loads the engine for several minutes at as close to full throttle as possible. (4) Kill engine and pull over while coasting (no idling the engine). (5) Pull the plugs and check them using the old white=lean, brown=OK, black=rich check.

 

You are probably all-right, but checking for a lean at highway conditions is a bit of insurance.

 

The Colortune "Blue" you got ... ? Did you find a spot where you went "Through the Blue" and then the Blue degraded because the Mixture was too Rich?

That is most definitely what you need to do if you are Tweaking MIKUNI's!

The Pilot system on MIKUNI is more efficient than HITACHI. Primarily because MIKUNI is a higher-performing Carb.

You would have had to have done a "Give and Take" Mixture set-up on the MIC'c to get dialed-in right.

As you worked the Pilot Mixture Screw ... adding Turns OUT ... the engine should have begun to increase in Idle ... such that ... adjusting OFF those high rev's would have been done down at the Idle Speed Adjustment Rod.

As each of the holes were brought-up to the Prime Air~Fuel Ratio ... the Idle Rod gets backed-off -- more and more ... until the Pilot System is holding the Idle with almost NO additional air from the Throttle Fly's.

MIC's can be Tweaked easier than Hi-Tots. The AIR Jets are Open to atmosphere ... Not enclosed up in the Carb Body under the Diaphragm with an additional AIR Restricting Plate.

Don't forget that the "Late Model" Bikes ALL came to the USA under the Strictest EPA Requirements handed-down at the time.

To get the Richness that will aid in allowing the Bike to give you its Maximum Performance you can do "A little Modification" that will let the Pilot System get Tweaked -- "Over on the Rich Side."

Use the "Tools" provided in a Very INEXPENSIVE Set of Welder's Torch Tip Cleaning Set.
The Tools fit the Opening of the PILOT JET -- just right!

You can use "The NEXT Tool up" and increase the Opening of the PILOT JET a bit more ... if you were so inclined.

Call it: "Creating your own ENVIRONMENT!"

 

Hey Frappe,

I'm getting similar results with my x550. I've got to turn the mixture scews out quite far in order to get the yellow flame. And BTW Rick, I'm not getting any rpm increase. Rather it runs really rough when I'v got it them screwed out that far.

I set the float bowls earlier this season, but I'll check other fuel delivery areas.

 

2 RickCoMatic:

"The Colortune "Blue" you got ... ? Did you find a spot where you went "Through the Blue" and then the Blue degraded because the Mixture was too Rich?"

Yah. My mistake I had to write this before...
On factory setting 2 turns out, engine misfires on all cylinders every few cycles?!
When I do 4 turns out ignition is regular but flame color is light blue.
At 4 1/2 turns flame color is optimal (darker blue) according to my perception :?
When i hit 5 1/2 flame is becoming blue and orange every few ignitions.
Everything wider than 5 1/2 causes orange flame with spots of blue.

Yesterday I have checked spark plugs after prolonged idling and they were blackish. Not so black but dry and black. That was enough reason for me to stuck Colortune in again. I have reduced all 4 pilot screws by 1/4 turn because that area seems to work still ok. If i reduce to 4 flame color is still darker blue but misfires some times. Lets say every six or eight ignition cycles...

Regarding rpm increase with pilot screws it did happen. Engine did started to increase rpm's a little bit maybe 200 or so.

I'm not comfortable with that idea of expanding nozzles. First I want to check everything else. I mean if 4 1/2 is OK i don't have anything against it. I'm not one of guys:"It must be 2 because it is like that in manual". Just want to be shore that this is normal condition...

2 SalCycle:

How many turns did you have to open to get in orange area of combustion flame color?
What preset do you use now? 3,4,5 turns out?
Which type of carb?

 

Hey Frappe,

I had my mixture screws turned at least 5 turns out before I had orange flame. But my plugs were pretty black with that setting, and it didn't run very well.

Oh, and I've got Mikunis.

 

You are not supposed to run engine at orange flame.
It should be blue.
Which setting do you keep now?

 

2 IllinoisMaxim:

I've done some high rpm filed testing.
You can see spark plugs on photo. It looks like example No.23 or 24 to me.
I realized that I must put some colder spark plug. Tomorrow I will buy CR8E. Anyway according to manual there should be CR8E on, not CR7E which I have now.

I will repeat test on highway...
I'm still burning that STP fuel system cleaner...

Spark plugs examples:

http://www.dansmc.com/Spark_Plugs/Spark ... talog.html

 

I would imagine ... that IF you are exceeding 4-1/4 Turns out and the Mixture is still looking "Blue" ... that there MUST be some additional AIR being introduced in order to keep the Ratio within "Blue" specs.

Where is that Air coming from?

 

Yeah, sorry, Frappe: I turned the screws in about a half turn and got a blue flame, and ran it like that. It ran poorly and the plugs were black and wet.

 

I agree Rick. Where the leaks are coming from, well, I suspect the boots, either before or after the carbs.

I just went for a ride, and on my way home it started running a little rough at idle and low throttle. Something may have worked loose. I'm letting it cool off a little before I go dig in.

 

Here I come again! 8)

I'm done with STP fuel system cleaner.
I have changed spark plugs to NGKCR8E which is colder than NGKCR7E.
After one shot of STP i have done colortuning again.

My initial setting, before STP, 4 1/2 turns had to be reduced to 3 1/2. It looks like this cleaning agent has done some job properly!
Anyway now it looks OK for me (that setting), and for my XJ, and for Colortune :roll:

But of course there is but! In Split we have experienced temperature increase from 25 to 35 degrees Celsius. It is 77 to 95 F. I know that with temperature increase mixture becomes rich. Please give me some expert-experience opinion on this topic.

Is it possible that STP did not affect this idle mixture screw decrease but temperature itself? Am I in "The Dark Zone" still :?

2 RickCoMatic:
I have new intake boots on carbs...
No air leak present at this time... At least I am convinced that way:roll: