Refuses to Idle

My XJ550 just came out of winter storage. Was running perfectly last season, ended last Oct. Now the bike starts on choke, runs on choke, revs normally on choke, but as soon as choke is shut off, bike dies... even after running on choke for 5 mins, engine nice and warm, still when choke shut off the bike just dies. It never did this before, carbs were extensively cleaned last season and ran perfectly.... could it be sticky petcock? electricals are all fine..

 

How well was it prepped for Winter Storage? This is the question!

That's going to tell us what need to un-stick, un-clog or reset. That it needs all that ENRICHMENT to keep-going ... something is clogged or closed or set wrong and the bike's not getting enough fuel.

Do an experiment:

Adjust the Pilot Mixture Screws OUT to 3 Full Turns OUT from Bottoming-Out. Try it.

If it runs good ... leave it until you can do some fine-tuning with a ColorTune Plug.

If it's idling too fast ... Run the Screws back-in ... as if the 3 Turns Out spot is 12 O'Clock and you want to adjust the Screws back-in ... "A minute or two at a time" ... across the board.

Tweaking 'em back-in slowly will bring the Idle DOWN ... eventually!
Don't be surprised to have none of this work and the Carbs yanked-off for a going-through!

 

To answer your question rick
I confess - I have 3 seca 550's , they sit in my garage all winter (gets cold in Toronto) - i usually drain the fuel tanks , pull the batteries out and store them indoors, leave all three on center stands, and hope to God the kids dont smash another rear lens with hockey sticks. I dont put oil in the cylinders etc, but if it gets warm enough I often pop out and grease cables and check tires , and generally fiddle etc. - PS the cars sit in the drive getting the winter treatment - at least I have my priorities right !! 8) ... I havent yet had to adjust pilot screws on any of the carb sets. My gut tells me its vacuum related, fuel flows in OK with richer mixture from choke - but not enough flows on idle? Petcock sticking - should I try the coke bottle check? I will try adjusting pilot screws.. BTW I wish it would warm up here - its still -4C and cold all week.

 

She if she'll run on PRIME

 

if my bike wont rev up should i try those screws too? should they be all the way in normally? could them being all the way in be my prob?

 

If they're all the way in ... Yes, that's a problem.

Try 'em at 3 Turns Out and see what happens; there!

 

are those the screws on top of the cabs closest to the engine or are they the big ones inside the carb that are brass colored? i know the ones inside are all the way in.

 

Quick hint........check your air filter box for mouse nests. Don't ask how I know.

 

Could leaky manifolds from the carbs to the engine cause those symptoms too? I'm not entirely clear on the whole process, but that would mean too much air getting in, and using the enrichment system would counter it, right?

 

oddly enough my abilty to rev the bike seems to be getting little by little better the more i run it?

 

Just don't turn the sync screws between the carbs. Your mixture screws are on the top front of the carb body, they may be under silver cap covers the factory puts in place, they have to be pryed out. Carefully turn them all the way in until they stop, (Don't force them) then back them out 3 turns.

 

So I thought I would respond to a few of the great posts here. My problems are still there , I adjusted the pilot screws out 3.25 turns and it made no dfference. The bike runs well on choke (5000 RPM) and will run at that rpm till warmish - but on pushing in the choke the bike drops from 5000 RPM to zero and conks out, doesnt even try. I have replaced the vacuum tube to the petcock, the carb manifold rubbers are all brand new, the air filter is perfect and clean, I checked the main fuses and cleaned them and they are all fine, I checked the voltage regulator according to the haynes manual,, as well as the alternator brushes. I ran the bike on main, prime and reserve and all are the same. I can switch the choke off if I rev the crap out of the bike, and keep it over 4000 RPM - but let go and it just dies.
Am I dealing with an electrical issue? Bad coil? Bad Ignition unit?

 

Also - Battery>?? - I replaced it 2 years ago - but - this kind of behaviour seems potentially related to sparking or lack of it, and insufficient juice from the battery at lower RPM would create this symptom. I will also double check the negative lead from the battery.

 

I starting to lean toward a "Fuel Supply" related issue.

It's getting enough Top-end from (a limited supply?) in the Fuel Bowl ... because it's sucking-it-up OK through the Enrichment Circuit.

But, when you close-off the Top-end Supply ... you lose fuel supply.

Float height.
Good float height -- but, Floats sticking closed.
Float Valve Filter Screens blocked.
Supply Line from tank kinked; blocked -- routed above Gravity flow.
Inline Filter "Air Bound" causing "Vapor Lock" type symptom.

(There's AIR in the INLINE filter that becomes a BUBBLE wanting to GO somewhere. Can't go down to carbs ... wants to travel UP to tank ... can't because incoming fuel blocks passage. The Bubble becomes compressed above atmosphere and the Gravity feed reduced in volume.)

Foreign matter stuck in the Right Angle of the Petcock Outlet.
Pull off the Hose and probe the Outlet back to the Valve Body.

Valve Body Rubber Disc not positioned properly limiting flow from Petcock when Vacuum Valve is open.

We got to be able to shake this out ...
Leave the Gas Cap open for a test ... too ... rule-out Vacuum issue.

 

Sounds like your choke circuit it working, but the choke circuit is different then the idle circuit, you may have to remove your mixture screws completely and spray out the passage down or up through the immulsion "brass looking" tube that sits down in the fuel bowl

The idle circuit requires that immulsion "brass" tube clear for that cylinder to idle as that's what pulls the fuel up threw to the top of the carb and past the mixture screw. Set the mixture screws generally about 3 turns backed out is a general rule of thumb for a starting point depending on if you have to test for emissions.

Keep pluggin away, you'll get it.

 

Are you sure your pilot jets are clear? A bike can run OK in mid-to-high range but idle like crap (or not at all) with plugged pilot jets. Just a thought....

 

So in the end it turns out that a complete strip down and cleaning of the Carburettors fixed all my issues, the bike is now running better than ever, idling perfectly and purring like a kitten. I bought a can of Yamaha Combustion chamber cleaner that did a great job of cleaning all the little parts and holes in the needle valve assemblies etc. My local Yamaha dealer said that the guys in the shop always use it as opposed to the carb cleaner. So advice to all, and I think Rick has said this earlier, strip the carbs and clean every little part thoroughly