Gunson Colortune Issues

So I've been working on my XJ700n for several years and it's been running okay the last 2-3. I don't need choke/enricher to start it and when I do use it, it normally doesn't start. Most times I have to start the bike with a little throttle until it warms up. Every couple of rides it would have trouble starting and seemed to be running on only 3 cylinders because it had no power and was fighting itself. I routinely had (what seemed like) fuel leaks and it was running too rich. I'd take the carbs off, take the bowls, flats, etc. off and nothing seemed to be wrong.

I finally broke down and bought a Gunson Colortune and Carbtune Pro to get everything dialed in correctly (thanks chacal!), starting with the colortune. I warmed it up a little yesterday and put the Colortune on C1. I got a weird yellow/blue color and when I adjusted the air/fuel mixture screw the color did not change. I took it all the way down to seated and still no change, but it did begin to stutter. Same with C2. Didn't have a chance to check the rest of the cylinders. When I cracked the throttle, it would change to bright yellow, then bunsen blue like it's supposed to, but at idle it's a weird yellow/blue mix. (I'll try to post a video if it uploads). When I took the plugs out, they were wet with fuel. I do have white smoke coming out of the pipes, especially when I raise the rpm.

Hogfiddles did a total carb overhaul 3ish years ago.
Valves are in spec.
New petcock internals last year.
I'm going to check for air leaks, but that doesn't seem right since it's running rich.

Only thing that I can think of is that the air filter got fuel on it last time it flooded into the airbox so that might be restricting the air too much and causing a rich condition. But, that still doesn't explain why I have no adjustment in the air/fuel mixture screw.

Thanks for the continued help guys!

 

is your gas old from end of last year? how do you store your bike for the winter?
are you running a stock air filter or the uni or possibly K&N filters?
I do understand your reluctance to replace a 45$ oem air filter.

never having to use the choke does sound like you have extra fuel flowing in the pilot jet circuit or restricted air
are the enrichment plungers fully seated?

may be time to do a spring cleaning of the carbs not a rack splitter but spray cleaner through the jets (remove the mixture screws)

how old are the spark plugs did you check the gap?

when were the valves last in spec?

do you run carb cleaner in the fuel at beginning and end of year?

pull the air filter see if it starts with the choke.

 

The air filter are the paper ones through chacal ($70), where do you find them for $45? (bike came with pods, found an airbox online and that solved so many issues...)

The fuel is old, but I put in new fuel (premium) with Sea foam at 1 oz per gallon. My end of season storage wasn't the best since the bike pretty much died, I limped it home in the fall, parked it, and got caught up with other things, but I did put a treatment in it, but don't think I ran it because it was having issues.

The spark plugs only have a few hundred miles on them at most. Since it's never quite run right (not fully tuned), I've gone through a few sets and whenever I popped a new set in, it would fire up and run well enough to scratch the itch as I kept working towards a tune.

I did take the carbs off and sprayed them down with carb cleaner and brushed them out, but didn't remove any jets. They did look really clean though, not quite hogfiddles eat-out-of-them-for-supper clean, but clean nonetheless. Looking back, I probably should've...

The valves were last in spec within 800 miles.

I'll try the air filter trick and see what happens and report back. Its 37 degrees out right now and snowed this morning so it's definitely on the colder end of operating temps.

 

I do want to note: It's been benched synched, but not Carbtuned to the bike yet because I read that happens last after the air/fuel mix has been done. If I got that backwards, just let me know and I'll Carbtune and then Colortune.

 

there are some who sync after each cylinder is color tuned,
do a sync then do color tune then sync again

 

So I tried the filter/no filter test. I got the bike started with the filter and some throttle. After it was slightly warm it would fire right up with or w/o the air filter in place.

With the filter: zero turns out on the air/fuel mix gave me blue
w/o filter: 1 turn out gave me blue, 1.5 started giving me the yellow/blue

I threw it on the Carbtune and the results are in the photo. This is with all mix screws at 2.5

 

Since the vacuum line is on C3, would that be throwing it off since it's vacuum is lower than the rest?

I'll do a synch now and see if that helps.

 

Update: in the process of doing the synch, I realized that there was fuel in the airbox. Cleaned it up and fired her up w/o the filter, turns out I have an abundance of fuel in the crank so I'll be doing an oil change and picking this all up tomorrow. Hope that helps with the diagnosis.

Then I'll try the running synch again.
Then the colortune.
Then synch again.

In the meantime, if anyone has any ideas why it's running so rich I'd love some input. Before I was chasing a hanging idle and we figured out what that was, now I'm chasing a rich-flooding condition

 

So I'm reading about the starter jet in another forum...can someone send a pic with an arrow of what I should be looking for to make sure it is clean...

https://www.xjbikes.com/forums/threads/i-need-some-guidance-with-my-bike.127461/page-4

 

not sure what this means. by vacuum line do you refere to petcock line? if so you do the sync on prime and the tool is all that is hooked to nipples.

 

fuel in the air box would make it run rich as it would be drawn into carbs. the question is why is there fuel in the air box.
may be time to clean replace floatvalve needle assemblies

 

starter jet is the long brass tube in that goes into the well on the sidewall of the carb bowl

 

Okay, that's what I thought they were referring to.

I have the brass needles and floats were wet set by hogfiddles so those are new and/or acceptable from when he cleaned it. Not discounting that they could be the issue, but they are the good parts.

With the fuel in the crank, when I cracked the throttle, it would spew up the vent tube and into the airbox. Don't know if that helps, but it was like a fountain coming out of there.

I also posted a pic of the current state of the filter after several soakings. I won't replace it til I get the rich condition figured out, but then I'll get one. No sense in buying another one when I know it's going to flood again.

 

P.S. how do you know when your starter jet is really, truly, zestfully clean? One of two ways:

a) shine a strong penlight or mini flashlight into the bottom of the bowl, where this jet passage "intake" is located. Look through the top of the bowl down into the jet passage "outflow" passage (this is the passage that the brass suction tube in the bottom of the carb body actually fits down into). Focus your eye carefully on the jet opening and make sure it's clean. P.S. it helps to do all this while in a darkened area.........see the picture "starter-jet.jpg" on page 2 of this forum thread topic for a great image of what you want to see!. It's post #23 by user FinnogAngela...........picture is titled starter-jet.jpg:

http://xjbikes.com/forums/index.php?threads/4050

Because the carbs are over-flowing (the needle valves are not seating properly, worn, or etc.) and that RAISES the fuel level in the bowls (and if nothing resolves their leakage, then eventually the bowls over-fill and the excess fuel goes into the airbox and into the cylinders, past the piston rings, and into the crankcase......even while the engine is off............this also means your petcock is either leaking, or was left in the PR (prime) position).

Even if it weren't over-flowing, a greatly increased fuel level in the bowls will make an engine run very rich.

 

Well the internals were all new when they left here. The rack shouldn’t have any issues other than needing the standard wetset/running sync/colortune routine. I’m wondering if you have an abundance of dirt in your tank that may be causing fuel valves to load up and hang open.

If worse comes to worst, send the rack back and I’ll go in and take a look at things. Maybe something has since worn out.....

 

@hogfiddles Did you wet set it when you did the cleaning, changed the float needles and looked at the floats? I thought you did, but if you didn't, that would explain some of it anyway.

I do have a sintered brass inline fuel filter connected to help, don't know if junk can still get through that or not.

To check if the petcock is leaking: do I just set it to ON and see if the hose will drip into a bowl/paper towel overnight?

I'm going to do an oil change, check to see if the starter jet is clean, and possibly check the wetset. I don't have a float height gauge, so I'll be checking the level based on the actual fuel level alongside the carb. For the XJ700 aircooled, it says 1mm +/- 1mm, so I should basically be right at the level of the lip where the bowl is recessed into the carb body, correct?

 

Correct.

This is the only way to actually check the fuel level; the float height gauge/ruler/etc. is just a method of seeing what "float drop" is occurring, and then using such a measurement to set the other floats at a similar position, the idea being that all four carbs are identical in the translation between "float drop" and the resulting "fuel level" (which is generally true, but not always).

See page 8:

http://www.xj4ever.com/setting fuel levels.pdf

 

Okay, that’s what I thought, just confirming. Got the carbs off the bike and now I’m checking levels. We will see where they’re at.

 

I set the floats to inital dry height. It is the owners responsibility to do their own dialing in. As well as for them to do the colortuning and running syncs.

 

Okay, well they were almost dead on, C2 was just a touch higher than it should be +1 mm above spec, but the others are all dead on at 1mm below the carb body. When I took the carbs off there was fuel in the airbox to carb boots in C1,2,4 but there may have been some in C3 too.

Update: Wet set is done, now I'm working on cleaning out the starter jet passages because they seem to be a little clogged.

Petcock does not seem to be leaking when set to "ON"