Running Very Rich

Hi everybody. I am having a problem with my 1982 650 Maxim. I finally got the bike to run, after sitting since 2001. I completely dismantled the carbs, cleaned them very well, and bench synched them. Now that I have them put back together, the bike starts very well with no choke. It runs very, very rich and will blacken the plugs in less than 5 minutes. I have actually turned the pilot mix screws down to 1/2 turn out, and it still runs very rich. Does anyone have some suggestions on where the fuel could be coming from? I checked the choke cable, and it has a little bit of slack when turned to off. Also, the "choke" plungers move up and down freely. There has to be something here that I am missing. Please Help!!

 

Floats not seating right, floats stuck, float levels not correctly set. Check all and see if that helps.

1/2 turn out is wrong, it is not the problem.

 

Could you tell if the Jets were all Stock ... or, did it look like somebody slipped a Jet Kit in there?

Somethings not right.

You're getting more gas than you need ... and its got to be coming through the Carbs ... one way or another.

Hows the Pistons ... free and free-falling?

 

Air cleaner cleam and air cleaner box free of mice?

 

Air filter is brand new, box is clear of obstructions. As for the jet kit, how would I know if they're not the OE jets? Also, floats are free and moving. Would you guys try setting them too low on purpose, to see if it fixes the problem?
Thanks for the suggestions!

 

no...set them right, so they are within spec. If you still have too much fuel, I am willing to bet the jet is allowing too much fuel to move from the bowl into the airstream. This sounds like a jet problem to me, but make sure your float bowls are not too high.

 

You need to look on the bottoms of all your Jets and write-down the Number etched on them.

If the carbs have been Cleaned recently ... please do a visual on the Upstairs Air Jets ... under the Diaphragm and little plate (if so equipped)

 

Did you happen to forget the washers under the main jet. The washer holds the emulsion tube down and makes a seal for the main jet.

 

That's good they are all moving freely.

Did you check the level with a tube on the drain method before you put them on the bike?

Did you check the float needles are closing completely?

No don't set them low, that will cause other problems further along.

Might be time to take the carbs back off and double check all the jets are in the right place, the 2 top jets (under the diaphragm) are not reversed as the Haynes manual shows the wrong way, with the bowls off and the rack upside down blow (gently) through the fuel line and make sure the float needles are sealing.

If all checks out we can go from there. Sometimes having everything "at bench" then going for a ride frees everything up and gives the bike a chance to clear it's throat so to speak!

When you say blacken the plugs is that 5 minutes idle or riding?

 

has this problem been solved yet ?? I am having the exact same problem with my 1982 maxim.....word for word .........

 

Have you gone through and checked everything is set right as per the previous posts?

Has the motor been synced and mixtures set?

Any modifications eg., pods 4 into 1 pipe?

Havew you taken the bike for a ride and seen what the plugs look like?

Tried a new set of plugs?

Correct Octane rated fuel?

 

Problem:
Way too RICH.
Why?
"Starts right-up from Dead Cold without a problem"
Enrichment Circuit issue ... or,
Pilot Jet issue.

Disconnect the cable to the Enrichment Valves.
Work the rod by hand.
Look to see that the Valves are indeed CLOSED and that the Forks aren't bent or incorrectly positioned keeping them open some.

Pilot Jets:
Wrong Jets?
Inspect the Jets and match the Size of the Jets in the bike to the Correct size in specifications section for Pilot Jets.

Air Jets:
Remove the Diaphragm Assembly.
Remove the Air Jet Cover Plate (if so equipped)
Check the Position of the two Air Jets.

Do NOT be confused by SIZE.
(See attached photograph for Correct Position of Jets)

The PILOT AIR JET ... is the LARGE ONE on top.
The MAIN AIR JET ... is the SMALL ONE beneath it.

These are AIR JETS ... not ... FUEL JETS.

The Larger Metering Port is Metering AIR ... Not Fuel.
Although it has a bigger hole than the one below it ... it IS the PILOT AIR JET ... and the LARGER METERING PORT does not mean its a MAIN JET.

 

looks like I am going to take the carbs off again and double check all of the above....I have put in new plugs and drove bike for about 6 miles trying to tweak as you suggested before.....no real luck so I re set pilot screws to 2 and a half turns out..after riding a while checked the plugs,here is the weird thing plug #1 real black.plug#2white.#3grey #4 grey

 

You are getting closer

Have another double check of the carbs, esp. the mixture circuits. The carbs need to be Clean. There might be just a small blockage, it is worth checking. Float levels too.

1 is too rich, 2 is too lean. Could be the effect of the YICS pulling number 2 lean there. Problem is probably with number 1 carb.

When riding at even throttle is there any hesitation? Any back fire?

For the Black plug wipe it clean with a rag then Burn the carbon off with one of those $10 butane pencil torches, being carefull not to burn your self and giving it a while to cool down when you have finished. Heat it till it looks like number 3 and 4 plug playing the flame round the bussiness end of the plug while you work. Great way of "saving" plugs while you test.

 

Is that #-1 ... dry soot or oily black?

 

Are your needles adjustable??

I had the very same problem and it turned out that my needles were adjustable... I moved the clips up 2 slots (one at a time) and it sorted it out.

Guy at the bike shop told me that the mixture screws only affect mixture up to around 2000rpm and the needles take over from there.

So what does it do when you're riding it on the open road? Splutter when you're cruising at over 2k rpm?, Only run well when your opening the throttle? Any backfiring?

 

even throttle seems to fire ok its when I hit the throttle hard it hesitates.back fires a bit. bogs a little isnt bogging nearly as bad as before .....the #1 plug is a dry black soot.not oily at all..

 

Dry black soot = rich, oily = burning oil.
Dry soot is better as problem is not worn motor!

Dirty spark plug will also cause hesitation and/or backfire/rough running. Clean or replace sparkplug. Wipe sparkplug clean then burn off remaining carbon using butane pencil torch (works for me).

Symptoms show rich on number 1 or maybe number 1 sparkplug not firing (replace sparkplug if in doubt).

Recheck and clean number one carb.
Re check 1 and 2 carb sync by bench sync.

Why I asked if hesitation at even throttle (say 5000 RPM on the highway in 5th) is I had 1 plug lead breaking down under load causing the bike to hesitate then surge then hesitate at even throttle. Also caused the plug to soot up. Bike was also hard to start, bog down and would backfire under load as sparkplug would sometimes fire igniting the unburnt fuel in the exhaust.

Check also for leak at exhaust gasket where it joins head. This can also cause backfire under load.

Try changing (swapping) number 1 coil lead to number 4 sparkplug and number 4 coil lead to number 1 sparkplug to see if problem changes to number four, if problems still persist after carb one has been cleaned and reset. This will prove sparkplugs, coils and leads are OK or not.

 

just wanted to give an update....I have double checked everything posted above..the floats were really the only thing that needed adjusting...put everthing back together..still starts right up cold with no choke..give it a bit of choke after starting ..engine dies...thats as far as I have gotten today...was reading the "on budget"post..is that maybe what I should try next??..is there a link for that ??thanks guys .....

 

Doug:

If it "Starts" ... with NO Choke ... It's already RICH enough to Fire Cold.

Adding more Fuel ... by opening the Choke ... only "Floods" it and it's WAY too RICH to Fire.

There are only 3 thing to troubleshoot ... because ... we know IT RUNS.

Fuel + Air + Spark = Fire

We KNOW its getting spark. Remove Spark from troubleshoot.

Fuel + Air +OKSpark

Fuel ... It runs Cold. Starts Cold. Fuel is present and is RICH enough to Start the bike Cold.

Air ... You Double-checked the AIR JETS.

That leaves FUEL Supply.

1. Pilot Mixture Screws are too far OUT ... Pilot Mixture Way too RICH.

2. Pilot Mixture Screws are NOT too far out ... but, Pilot Mixture is RICH.

CHORUS:

PILOT FUEL JET = Incorrect
(Factor in: Hitachi Carbs -- Main Jets and Pilot Jets can get "Confused"

I can see the light coming-on over everybody's head ...

Is there any possibility that you might have ... Oh, how do they say in America ... Fogged-up the placement of the Pilots and Mains?????

 

If the jets are all ok, how do you make 'em run less rich? What needs adjusting? Float levels?

 

The Pilot Air Adjusting Screw ... Better known as Pilot Mixture Screw
On the Top Front of the Carbs.
Just to the side of the Enrichment Valves (Choke).

Generally, that Little Brass Screw controls the Richness of the Mixture for:
Idle: The Correct setting allows the bike to Idle and run after the engine is warmed-up and the Enrichment Circuit (Choke) is closed.

It continues to supply Fuel when the Throttle is Opened ... supplementing the Richness as the Throttles are Opened and the bike brought Off-Idle and accelerated.

The correct Mixture allows the Bike to Idle smoothly ... and, continue to supply -- just enough Fuel to maintain the correct Air-Fuel Ratio during the brief time that MORE Air enters the Combustion Chamber until the Fuel from the Main Jets gets drawn-in by that increased Air Flow.

Too far IN -- and there isn't enough Fuel, momentarily, and the bike hesitates (waits for the Main Jet Fuel to start)
Too far OUT -- amd there is too much Fuel, momentarily, and the bike "Bogs-out" from not having enough Air to let the Fuel ignite, and burn as its supposed too.

The Factory setting is: 2-1/2 Turns OUT from the Bottom.
It has been determined that the Factory set-up is a bit too Lean.
Most everyone who does not have the ColorTune device adds an additional 1/4 -to- 1/2 Turns OUT to add Richness and improve performance.

Those who have used the ColorTune device report that 3 Turns OUT or more is where the ColorTune Plugs shows it optimum Richness for the precise Air-Fuel Ratio needed for Idle and best perfoormance coming-off Idle.

If yoou find that the Pilot Mixture Screws are set to 2-3/4 or Less ... make the adjustment necessary to set them to 3-Turns OUT -- temporarily ... until you have the Tools necessary to fine-tune the adjustment for a precise measurement and best merformance.

 

Ok, sounds simple enough. Couple of questions though (and please bear wtih my newbie-ness):

The Pilot Mixure Screws aren't the same ones on the throats of the carbs that you use to synch them, are they? (FEAR! -- I just had it synched at the shop...runs noticably better even though it's rich) Can these be adjusted while the carb is still on the bike, or do I need to pull it?

What's a ColourTune device? Sounds sexy.

Too bad there's not a decent exploded view of the XJ carbs available. The one that keeps popping up here is so grainy.

 

If you have Mikuni Carbs the pilot mixture screws are the teensy weeny ones that sit on top and at the front of each carb. Usually recessed in a tiny hole. If you sit on top of the bike sans tank and look down at the carbs you will see on the top of each one (in front of the chromed cap) the relevant holes. If they have never been touched before (unlikely) they may still have the plugs in them.
See how you go.

 

Check that last. I found a nice clean carb exploded view. Anyone want me to scan it and upload it to the site for general enjoyment? Point the way...

 

Thanks Redcentre. I've got it figured now. Will have a nice leisurely wrench on it this weekend.

Anyone know where I can pick up a new starter plunger for this carb? One of mine is a bit sickly.

 

Just clean it ... its made out of Brass so it will last forever.

Take it apart.
Remove the Rubber Dust Cover
Take the Plunger out of the Brass Body
Set the spring aside
Shine the body of the Plunger with 1500 Wet using WD-40 as the wetting agent.
Roll a small, tight-fitting portion of the 1500 and put a new shine in the Inside Diameter of the Body.

It's like NEW; again!
Put it all together and stick it back in there!

 

Ok, so, have been monkeying with the pilot screws all afternoon. At 2.5 to 2.75 turns out it runs pretty smoothly and responds not bad when I road test it, but still isn't as smooth as it should be...still a *bit* of bogginess on takeoff from start.

Also noticing that the hotter it gets, the rougher it runs on takeoff. Eventually I had to quit with the pilot screws as I was getting bogginess on takeoff no matter where they were set.

I had a local machine shop redo the valves last summer and the guy at the machine shop said that if the valves are buggered it'll act like that -- not bad when cool, but crappy when hot. Valves are fixed now, though (supposedly...).

Any ideas?

 

Sync?

 

"The HOTTER it gets" ... Is this an overheat problem ... or, as the engine heats-up to a normal running temperature for an air-cooled bike?

(Fill-out the "Signature" feature with Thumbs ... so we get important info at a glance, please.)

Are you having to add oil frequently?
Can you run a test on a set of Brand New Plugs?

Will you have a look at the space between the Air Filter and the Boots.
Wipe a paper towel on the bottom of that space, there, and let us know what that situation is.

Look at ... and run a test for ... Air Leaks around where the Airbox Boots are clamped to the Carbs and the Manifolds between the Carbs and the Head.

Move all the Pilot Mixture Screws OUT to:

1. More than 2-3/4 ... but, not quite 3.
Test.

2. Half the distance between 3 -- and 3-1/4 ... (Just a little-bit beyond 3)
Test.

Tell us what you have after you get all this homework assignment done. I think we're "On the case."

 

No, not overheat. Just up to normal running temperature -- or maybe a bit warmer for sitting so much running while I'm tinkering on it, but nothing alarming. It's oil tight, not using or burning oil (has new rings). *Tiny* bit of ooze at the top cam-cover gasket, but not major.

The plugs are new...well, they were when I started this latest set of tests. I'll pick up new new ones tomorrow. Still carboning up at 2.5-2.75 turns on the pilot screws, but not as badly as before. Odd thing is if I turn down to 2 turns, it chokes out...too lean, but still blackens the plugs. The plugs are the ones the manual recommends for the XJ550, so they should be running hot enough, although I'm tempted to chuck in some hotter ones just to see if it makes a difference.

I tested it at 3 turns out today already...gets a *lot* more boggy at anything much past 2.75 turns. Want me to go past 3 turns anyway, just for kicks? The sweetest spot I can find is 2.5-2.75-ish, but even there it's not what you'd call perfect. Still hesitates and stutters a bit on take off. Could the hesitation be because of a sticking slide valve? I'm tempted to tear it apart *just* to try the drop/clunk test out of curiosity.

No air leaks around the boots going from the airbox to the carbs or from the carbs to the engine. The clamps on all are tightened right down firm. Also, the boots between the carbs and the engine are new, so no cracks, etc. However, just to be certain, how do I test for leaks here?

I predict that the space between the air filter and the boots will be greasy and black -- a month ago when I embarked on this epic, it was SO rich it was actually pouring gas down into the crankcase past the pistons when it was sitting at rest (not running) and by the time I noticed it the gas/oil mix was puking up through the crankcase blowback vent and into the breather box. What a mess! Set the floats higher and the problem stopped, but then I ended up where I am now -- still rich, but at least it runs for more than 2 kms. Mechanic who synched the carbs thought it might be dirty, so he pulled it apart and made sure the vents were clear (they were...I've got an in-line filter), and said that the floats were sitting a bit high. I told him to leave them or I'd be back to having gas in the oil. Anyway, will clean everything out good and then test it again after it runs a bit tomorrow and let you know what's what.

BTW, KiwiXJ750D, it's synched. Just had it done at the shop this past week -- with fancy tools and such, which I don't own.

Speaking of which, what's a Colourtuning device?

Rick, thanks for being "on the case"! This thing is frustratin' me to death!

 

Float problem needs to be fixed. Float needle and seat not sealing. Float level too high might cause the problem you are having as you have ruled out idle mixture. Colourtune is a sparkplug with a clear fitting so you can see the spark while engine running to set mixtures.

 

Test for Air Leaks using a Propane Torch.
Don't light it.
Just Probe all over the place for anywhere that causes the rev's to spike.

I think you're running lean and burning Valve Seal leaks.

The lean condition is allowing the burn to consume the oil and render it dark ash.

Google: Marvel Mystery Oil ... read about adding-it to your crankcase!

I hope it ain't Valve Seals, Brother.
That just ain't good.

 

Hunting for a leak on your intake is as simple as using a can of WD40. With the engine running, spray the 40 around the junctions of the boot. If the rpm rises, you have a leak that was temporarily blocked by the fluid. This applies if your idle is hunting, it smooths out when you hit the leak.
Rick will probably tell you to use a can of UNLIT propane and listen for the rpms to climb when the propane gas is introduced into the combustion mixture (extra fuel = more RPM). Just don't use this method if you know you have cross over (induced arching from deteriorated plug wires) or other open sources of ignition.

 

Ok, back at last. Sorry for the delay in getting back on all the advice -- last week was somewhat insane.

However, I digress. Here's what I've done since my last posting:

1. Shiny new plugs.

2. Pulled the carb, did a "clunk" test (very clunky I'm happy to report).

3. Raised the floats a bit more (about 1 mm).

4. Double checked pilot screw adjustment all at 2.75 turns while they were
easy to get at.

5. Reassembled and checked for air leaks with both propane torch and
WD40. No leaks.

I think the floats may have done it. Once I got it primed, it started right up, runs smoother, and responds much much better on the road. No bogginess to speak of at the bottom end -- had a tiny bit after I'd sat at a stop sign waiting for a break in traffic for about 2-3 mins, but not anything like it used to do. I'm giving it a minute to cool off and am going to pull the plugs to see if they're any less black and fuzzy than they usually are.

I'm going to take it out for a good run today (if it stops raining) and see how it goes.

RICK: I've got some pics of the inside of the carbs, same view as in your post on June 19. Mine doesn't look the same and would like to post the pic to the forum to see if I might even be running the wrong carburetors on this bike. How do I post images here?

Thanks,
Mike

 

You look above the QUICK REPLY Box and above the Blue Line ... on the Left is "New Topic" and "Post Reply"

If you click on Post Reply ... you get a page that allows you to add pix and attachments.

 

Ok, but it asks for a URL address, and I just want to upload it from my hard drive. Tried to just put in the path to the folder on the hard drive, but all it posts is the actual path, not the pic. Argh?

 

Ran it hard yesterday and the plugs are much improved. #1 & 4 are black but not fuzzy. Around the contact points they're burned clean. #2 is perfect -- nice and grey. #3 is almost as nice as #2, but has a bit of wet-looking carbon on it.

I've turned back the pilot screws a quarter turn. Will run it again tomorrow if it's not raining again and see what the plugs look like.

I think I may have a pulse here. It's alivvve!

Muahaha!
Mike

 

Once you get it "In the Ballpark" ... you don't do them ALL "Quarter-turns"

You concentrate on the Holes that are obviously needing adjustment one-way or another ... and,

Begin Tweaking like you are adjusting the Second-hand on a Stopwatch!
You add or subtract a little bit of Tweak one or two seconds at a time.

Use a Fine-line SHARPIE to mark the spot you are adding or subtracting from.
Then, if you find-out you've gone too far ... one way or another ... all you need to do is look for your MARK and Tweak to it.

As the situation IMPROVES ... wipe off the Mark with a Kleenex wet with Carb Cleaner and make a NEW mark!

 

I don't know where you ended up to see it asking for an URL!

If you look down at the bottom of the thread, just above the solid blue "Quick Reply" bar, on the left side, you should see the "New Topic" oval, and "Post Reply" oval buttons.
Click on the "Post Reply" button, a fresh screen will apear with "Subject" on the top, the next line is "Message Body" with the different formatting features available, then the actual mesage area to type in, followed by another solid blue bar labeled "Add an Attachment".
In that lower section you will see "Filename" with a "Browse" button off to the side of it, if you click on the "Browse" button it will open a window of your hard drive. Locate your file, highlight it and click on "Open", this window will close.
You have to click on the "Add Attachment" button before it will actually attach to your post. NOTE: picture file must be 500 x 480 to be added this way.
Finally, click on "Submit", wait for it to do it's thing, and you've just added a post with a picture in it!

You can also get to the "Add an Attachment" section via the "Quote" button that's on the top right side of each persons post.

Hope this helps.

 

Yep, I'm definitely an idiot and someone should take my wrenches away before I hurt somebody. 8O

I was looking above the message body window where there's a button (looks like a little mountain in a box) that says "insert image" rather than looking down at the "add an attachment". D'oh!

So now that we've got that sorted out, here's a view into my carbs (#3 & 4). Note that there's only the one screw in air jet and the other is just a hole. No threads in that one at all, so nothing is missing. Are these the right carbs for an XJ 550, or am I working on Frankenbike here?

Thanks for any insight.

 

A 550 Owning Member will have to verify that.

The only 550 I've seen around here; is one abandoned by it's owner at a Garage in a nearby town.

I bought it.
I doubt it can be restored. I'm sure it's been vulture-attacked and vandalized.

There's a good engine and few other parts. Once it gets delivered, here, I'll see who wants what.

 

that's exactly what mine look like. the Mikuni BS28's.

 

check the intake side inlet. There may be a pilot screw in there. I can't remember, but that may be the second air pilot screw.

 

Where's the intake side inlet?? Must check my schematic...

 

what I meant was the opening that the rubber boots connect to the carbs from the airbox. Look in there and you might see a little opening with a pilot screw in it. I'll probably have mine off this weekend, so I will look at my 550's Mikunis.

 

Oh man...that's gotta be a pain to adjust...

 

not as bad as the floats....damn I hate that setup. And I have to raise mine...perhaps tomorrow. I'm tired.

 

ok, so I cleaned and re-set my floats today. There is no pilot screw where I thought there might be. Only ones I found to remove were the two in the float bowl, and one up under the diaphram.

I also found that when I pressed out the emulsion tubes, there was a lot of grit and corrosion on them. So I soaked them, scrubbed them and wiped out the bores. They installed very easy without all that crud in there. It's odd because it was running rather well before, now that it is actually clean...who knows.

 

On the 550 ... The Main AIR Jet is under the Diaphragm. There, it should be fairly protected from contaminant entering the Main AIR Passage which supplies the Metered flow of air surrounding the Emulsion Tube.

On the higher displacement bike's running MIKUNI's ... The Main AIR Jet is located on the Inside Diameter of the Carb Body Main Intake.

The Main AIR Jet being located there is susceptible to contaminate from the CRANKCASE.
Since the Crankcase Vent is routed to the Airbox ~~> INSIDE (After) the Air Filter ... Oily gases can be drawn-up into the AIR JETS contaminating the Air Passages.

If you are experiencing problems with Low ~ Medium Power-band Acceleration and Find the Emulsion Tubes Fouled on the Outside Diameter of the Tube ... Flush-out the Main AIR Passage with the Emulsion Tubes Out of the Carb.