Yet another tuning issue

Long time follower of the forum. I have learned so much and can't thank you guys enough. Here is my issue:

82 XJ550 Maxim
Purchased 3 years ago and has never ran "right". I am determined to get this bike running the way I know it can (my friend has an 81 XJ550 that reminds me regularly of how my bike is lacking!)

Here is what I've done:

-Carbs Rebuilt - completely broken down, zestfully clean, replaced float needles, bowl gaskets, pilot screw o-rings. All jets are stock (now). Float levels have been wet set (on bike, level left to right and front to back with block under the front tire) 3.5mm below float bowl gasket. One can never be 100% sure but I feel confident in the setup of the carbs.
- Valve clearances checked - I checked my clearances, several of them were too big. I ordered the correct shims and installed them. (Interesting note: After installing the new shims I re checked the clearances and they were drastically tight. I thought maybe the engine needed to run to "seat" the shims in place. This may be an issue)
- Synced carbs with Carbtune and YICS port blocked.
- Adusted pilot mixture using Colortune. This is where things get interesting. Carbs 1, 2 and 3 acted strangely. The color was yellow consistently until I had the screw completely closed, at which point is turned slightly blue (clearly not correct). I can get the bike to a stable idle, but if I add any choke it stumbles and dies (my past experience is that adding choke will increase rpms.) I pulled the plugs and they are black and sooty. At one point Carb 4 was 1.5 turns out and the plug was actually white (indicating a lean mixture).

I have the YICS tool and the Carbtune on rental from Len so I'm hoping to get this resolved soon. My first step will be to go back in and recheck the valve clearances. Any other ideas?? Thanks in advance guys!

 

I ordered the correct shims and installed them. Did you use the correct chart??? I only ask because first time around, I used the wrong chart (Interesting note: After installing the new shims I re checked the clearances and they were drastically tight. I thought maybe the engine needed to run to "seat" the shims in place. This may be an issue) Yes, it will be an issue, Re check valve clearance, motor needs to be cold, room temp
- Synced carbs with Carbtune and YICS port blocked. Moot point until the valves are in spec....
I go to Vegas every year, and I would be willing to wager if you did rebuild your carbs completely broke the rack down, throttle shafts seals and all and was anal about zestfully clean, and have your valve clearance in spec, and then sync and colortune, I bet you will see a world of difference....

 

is the bike exhaust, air box stock, and air filter fully stock ? what jets are in it now and what was in it?
did you do a compression check ?what were the numbers?
when you replace the shims you have to turn the engine over a few times to force the oil out from under them, or run for a day then recheck.
setting for wet set fuel is 2mm below plus/minus 1 mm below carborator chamber mixing body NOT GASKET.
so depending what you mean by gasket your fuel levels could be to low or to high .
which could be why you run rich if set to high
did you install new mixture screws? if you have to almost fully seat them could be worn or wrong part.
are you sure your enrichment plungers are fully down when you shut off the enrichment circuit (choke)? if not this could lead to richness.
when are you turning on the Choke before or after starting? if you are running rich you may not need as much choke to start.
what is your idle set to? is it the same after 10 miles of riding?

was the tip of the insulator of the of plug 4 starting to turn paperbag brown? if so it may have been the correct setting. how long did you run before reading your plugs.
have you done a plug chop yet? I would suggest an idle one as well this will isolate when you start running rich.

 

Fuellevels are a key component to having the correct mixture. A high level will result in being rich. XJ550H gives good advice. Follow it.

 

i forgot something. to check if carbs are level when on center stand check fuel level on carb one to carb one. then check fuel level of carb one to carb four.
after you check levels run bike for a few minutes then recheck levels.

 

Great! Thanks for all the responses. Here we go:

- Exhaust, Airbox and filter are stock (although not originally, PO had pods and alternate jet sizes)
- No compression check - not sure I have the tools to do this
- I have run the engine a fair bit since replacing the valve shims, rechecking clearances is next
- I have attached photos of my fuel levels
- I did not install new mixture screws. Replaced the o-rings though
- The enrichment plungers are fully down when running the bike. The choke "issue" happens when the bike is running. It starts and idles with no choke and then when choke is added the bike dies.
- Idle is set to 1300-1500rpms. I have not ridden it long enough to see if that changes. The bike is difficult to ride as is. Bogs down at low rpms, etc. Plug chops are on the list now.
- When I rebuilt the carbs they were completely broken down, throttle shaft seals and all. I was extremely anal about cleaning them and replacing rubber parts that were worn.
- Jet sizes - Main 112.5, Pilot 35

I will update with valve clearances in my next post. Here are links to fuel level pics:

https://drive.google.com/file/d/0B47oYEUgDxqfeU9pelZQMzBaMWM/view?usp=docslist_api

https://drive.google.com/file/d/0B47oYEUgDxqfODM2cXpyTVNrSWc/view?usp=docslist_api

https://drive.google.com/file/d/0B47oYEUgDxqfTHlsNHJuRWQ3WDA/view?usp=docslist_api

 

When you cleaned the carbs did you remove the air jets? Did you put them back exactly where they came from?

Your fuel levels look to be a little low.

The bike starting from cold without choke, and bogging with the choke on and the engine warm tells me that you are rich at idle.

Given that the bike had pods, and the carbs were rejetted, and you can't get the idle screws to adjust to a lean mixture, I think that you may have aftermarket idle screws (and possibly aftermarket slide needles)

 

Yes. When I cleaned the carbs I removed everything but the emulsion tubes. I'm confident that everything went back in its appropriate place.

https://drive.google.com/file/d/0B47oYEUgDxqfOXlEOVRBb1YwQ1k/view?usp=docslist_api

Does the screw look stock? I'm not sure I would know the difference.

The confusing part is how could low fuel levels and a rich mixture at idle coexist. I have gone back and forth with this bike. At first it was utter frustration but now it's more like the world's greatest challenge.

 

Updated Valve Clearances:
Intakes (1-4): .127, .076, .127, .076
Exhaust (1-4): .178, .178, .152, .178

I2, I4 and E3 are all too tight. These used to be:

I2: .152 with shim 275 (now 280)
I4: .152 with shim 275 (now 280)
E3: .203 with shim 265 (now 270)

Should I go back to the original shims for those?

 

UPDATE:

- I went back to the original shim sizes on I2, I4 and E3.
- As I was putting things back together one of the plug caps got snagged up and pulled off. This got me thinking about electrical. I went ahead and tested some resistances and fitting the plug caps back onto the wires. I noticed that I have 5K ohms plug caps ... is this correct? I measured coil resistances and they were in spec. I am using non-resistor plugs. Everything normal here?
- Carb synced w/ YICS blocked
- Colortuned - Hard to read the color during the day, but #1, 3 and 4 acted differently this time. Starting from completely screwed in the flame jumped immediately to yellow as I unscrewed. At one point (~2 turns), the yellow went away and it appeared to be blue (although the flame was quite weak). #2 is still the same, constantly yellow unless screwed all the way in.
- Test Drive - Bogging down at low RPMS. Plug Chop - Black, sooty. Classic Rich running symptoms.

In regards to aftermarket idle screws and slide needles ... I can rule out aftermarket slide needles as I have compared those with my buddies 81 XJ550 and they are identical. I took a picture of the idle screws, they don't seem aftermarket to me, but I really have no idea.

What am I missing here guys???

 

Did you re-measure the clearances?

XJ550's should have 10K resistance per cap, but it doesn't matter enough to cause a difference in regards to the problems you are experiencing. Have you considered changing the spark plugs to a new set?

This is not the way it should work. At a fully turned in position, there should basically be no fuel coming thru the pilot circuit, so the engine will either stall or be REALLY lean (white). As you gradually turn the mixture screw out, it should become blue, and as the screw is turned even further out, then the flame color will go yellow (rich).

If turning the screw out just slightly from bottom (fully closed position) results in a yellow flame, then you have a problem either with the fuel levels being WAY too high, the jets being WAY too large, or the choke being partially open ALL the time.


My guess is the fuel level is too high, or the choke system is constantly leaking a small bit of fuel. Have you inspected the ends of the choke plunger valves for any deformities, bent/broken tips, damaged rubber "seat", etc.?

 

Thank you for the response.

- Yes, I re-measured the clearances and now they are all in spec.
- I thought those caps were not right ... what would the symptoms of having not enough resistance be? Could that contribute to rich running conditions?
- I posted photos of fuel levels and another member thought they looked low if anything
- The jets are all stock, verified side by side with the carbs from my friends 81 XJ550 (which runs well).
- I have not done an in-depth inspection of the choke plunger valves. I can pull those out and take a few photos. They all appear to be seated fully when the choke is off.

Because the plug fouling and strange colortune behavior is occuring on most/all of the cylinders it has me thinking of more global issues like ignition (weak spark), etc.

I'll go pull those choke plungers!

 

did you ever change the air filter? take it out and have a spin around the block

 

https://drive.google.com/file/d/0B47oYEUgDxqfNTgyMXlvOG8zM0U/view?usp=docslist_api

https://drive.google.com/file/d/0B47oYEUgDxqfUE9SY2ZmX2dOdWM/view?usp=docslist_api

Choke plungers look good to me. Fully seated.

Welcome Polock! Interestingly, the PO had pods installed. I purchased a stock Airbox/filter and installed it. The air filter is currently relatively clean. I did your suggestion and the bike ran poorly. Still bogged down at low rpm and stalled once.

What else?

 

PO also mentioned that he replaced the TCI. Is this one correct?

https://drive.google.com/file/d/0B47oYEUgDxqfUEdrbkZqbUJjLUE/view?usp=docslist_api

 

I don't see how you can get an accurate float setting with the carbs on the bike. The carbs have to be perfectly level and I found that somewhat difficult off the bike with leveling rig I made. I had to tweak my floats several times and run gas through them several times before I could get a consistent reading on each float. I'm betting your float levels are off.

 

well without a air filter it should have run leaner. now to the pods and richness, i'd have a real close look at the jets to be sure the po didn't drill them

 

I took some photos of the fuel levels and posted links. Another member mentioned he thought they might be low if anything.

 

Yeah that's what I would have thought ... more air = leaner. Not much apparent change on the bike though.

The PO had different jets installed (Main 117.5 and Pilot 45). The jets in the bike now were purchased new.

 

I agree with chacal...the fuel levels are too high causing the rich condition. The fuel should level right about equal with the top of the washers. Cameron, a shim is 2mm thick.

Gary H.

 

Thanks Gary! I'm getting some conflicting info on fuel level. Did you see the photos? The top of the washers is 5mm below the chamber body. I've always read that spec is 2mm +- 1mm. Also could you go into more detail about the shim ... not sure if I follow.

Here is a video: I'm noticing a tiny amount of play in the enrichment plungers when the choke is off. Is this normal?

https://drive.google.com/file/d/0B47oYEUgDxqfNHpMRk1xRzB5MTg/view?usp=docslist_api

 

Yes.

 

Looked at the photos. The levels look correct. Dis-regard the "level with the washers comment ". I was wrong. 2mm +/- 1mm is correct. Also disregard the shim comment.

Gary H.

 

Thanks guys! Keep the good ideas coming.
The fuel level issue is a mystery. Big Fitz was preaching fuel levels 3 YEARS AGO:
http://www.xjbikes.com/forums/threads/running-rich-not-sure-what-to-do-next.38602/
This bike has never run well for me, made even worse by the fact that my friend has an 81 XJ550 that rides on wings. The float heights are set exactly like his. I used a digital caliper to measure them dry and their are photos of my current fuel level. Is it high or low??

 

Ok, now we have 1 vote for low and 1 vote for ok. Either way ... why am I running rich? Also, did you watch the video of the enrichment plungers?

 

Make sure that the slide needles are in good condition. I had one with a bent tip. That broken tip caused that cylinder Der to run mega rich, no mater what I did with the carb.

 

If you measured the levels and they are within spec they should be fine. I don't want to confuse you with unnecessary information. On that note the emulsion tubes do need to be cleaned. Imo if the enrichment plungers are seating all the way down that play shouldn't be the problem.

Gary H.

 

Also as k-moe advised...check the location of the air jets. Make sure the fuel needles have the stock part # on them. Iirc the 650 stock needles are y10.

Gary H.

 

but this is a 550 i thought? i make the choke cable have extra slack when the choke is off so the fingers are kind of pushing the plungers down.
did you ever do a compression test? How's it run towards top end?

 

Thanks for the idea. I have inspected the needle tips, they are all straight and in good condition.

The emulsion tubes are the 1 part of the carbs I couldn't get out. I didn't want to risk destroying the carbs to remove them. If it ends up being those, that will be the mother of all irony.

Here is a photo of Carb #4:

https://drive.google.com/file/d/0B47oYEUgDxqfUm5XckwyT21rbUU/view?usp=docslist_api

The jet that is in the lower left of the photo is #165. That should be the Pilot AIR jet correct?

I checked the needles. They are 4GN15 ... is that correct?

Thanks again guys. If I get this one going it'll be a victory all around!

 

We need 550 to chime in. Idk what the # should be. Hang in there...the members here are good. We'll figure it out.

Gary H.

 

Yes a 550. Is there a tutorial on the forum for a compression test? Have not done one before. When I rode it today it had nice pull from 3k to 6k rpm. 1.4k to 3 k not so much. Good idea about putting slack in the choke cable ... that completely removed the enrichment plunger "play" from the video.

 

this is bad

 

Don't tell me I have to go in and try and remove them! You really think that could be it? I had the whole carb body submerged in Carb Dip ... surely those tubes must be clean.

 

According to the catalog it is correct:

HCP17591 Aftermarket Mikuni main jet NEEDLE, correct for all 1981-83 XJ550 Maxim model carbs (BS28 series), replacement for the original 4GN15 single-position needle. Use 1 per carb. Ring cap, c-clip, spring, and spring seat washer are not included. Each:
$ 21.95

 

Absolutely. The tubes are directly linked to fuel metering in the bowls. The tube and holes MUST be clean.

Gary H.

 

Got any ideas on how to get those puppies out? They were really seized in there. Do they pull straight out or unscrew??

 

If they are seized like that they are definitely a issue. The tubes on the hitachi pull out. Idk about the mukuni. Got any pictures?

Gary H.

 

Wait! I do remember these coming out last time I cleaned. They tapped out. Long brass piece with many holes in it. They were definitely removed. I was confused with the seat the float needles sit in ( which were an absolute bear to remove, damaged so bad they had to be replaced). Sorry for my lapse of memory, I've cleaned these carbs more than I'd like to admit. But the last one was the real deal and I'm 100% confident the tubes are sparkling clean.

 

Is the orientation of the spring, washer and o-ring correct on the mix screws?

Gary H.

 

From bottom to top: O ring, washer, spring, screw. Is that right??

 

Correct.

Gary H.

 

read your factory service manual the only concern is level side to side not front to back. the carbs are not level front to back when mounted on the bike.

cam take that board out from under the front wheel when you check the levels
cam you said When I cleaned the carbs I removed everything but the emulsion tubes. these tubes under the main jets have 16 tiny holes in them that allow the fuel to mix with air before entering the carb throat if the holes are plugged you will suck unasperated fuel into your carbs which will result in a rich condition.

i am not sure how this will affect you at idle it is possible that PO shimmed the slide needles leaving them open a little at idle which would allow fuel to flow before it is ment to .
did you soak the enrichment plungers in carb cleaner? this is not advised as it will affect the "rubber" that holds the pin. when you color tune try pushing down on the plunger

 

the screw goes through the spring then the washer and oring is on the bottom you are correct.
the washer supports the spring and compresses the oring for the seal

to remove the emulstion tubes you go from the top pull out your slides remove the main jets and use a small dia wood dowel inserted from the top of the carb and gently tap them out using a small mallet.
to help loosen any crud spray carb cleaner into the main air jet it is the one on the right side of the carb body when viewed from the carb boot to air box it is nor removable.
this is the inside of your carbs
http://www.xj4ever.com/inside your carbs.pdf

another must have
http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

 

Thank you so much for chiming in. I'm starting to run out of ideas beyond replacing parts like enrichment plungers or jet needles. Any other ideas?? Ignition system?

 

from xj4ever catolog
Original main needle size configurations are as follows:

4GN: used on all 1981-83 XJ550 Maxim carbs.
the original 4GN15 single-position needle.

MIKUNI PILOT AIR JETS:#165 XJ550 Maxim models (1981-83)
MIKUNI PILOT FUEL JETS: #35 XJ550 all 1981-83 models

MIKUNI MAIN AIR JETS: not replacable or removable
MIKUNI MAIN FUEL JETS:#112.5 is used on:XJ550 all models

 

I just had them out. No shim that I can see. But that size is in all 4 carbs

 

Check, check, check.

 

lens catalog is a great sorce of info as well as parts.
i think you should clean the emulsion tubes.
look at the 2 links i posted above
inside your cards is a great visual
have you ohmed out the coils I think you said that you did 5 k resistors in the caps.
ohm out your pickups to you can do that from the leftside tci connector should be a black common wire and a brown wire and orange it pickes up the signal for the tci spark

 

I checked the resistance for pickup coils. It read 2.9 ohms for both. Slightly on the high side ...what do you think?