non-running xj550

okay, im about ready to push it to the curb...

i got the mikunis back from Rick, finished them up (fasterners and such) and mounted them...

had the headpipes hanging on it, the air filter out and fired it up. it started right off the bat with no choke or throttle needed. it raced to 6,000 rpm and i hit the kill switch. it jumped right up there 3-4 times until i got the idle adjustment turned down to about 1,200 rpm. adjustment of the pilot jets resulted in NO change in idle or throttle response which was poor. the bike ran really rich and would start to bog down with the slightest increase of throttle...

i finished hanging the collector and the mufflers and popped the air filter in...

the bike would then sort of run, sometimes requiring the throttle to be cranked wide open i realized i had the throttle and choke cables backward. regardless i had lots of troubles with the idle and starting...

i swapped the cables to the proper connection and tried it again today. the bike did not want to start. it cranks just fine (thanks to the new battery) but it wont fire with any regularity. i pulled the plugs and cleaned them and checked for spark. all good. i decided maybe they were too worn so i bought new plugs...

the guys at the shop said they were gapped from the factory so i popped them in. still no start. at least not like it was before i put the mufflers and collector on. sometimes it would fire off but would run like it wasnt getting any fuel and the idle would just dwindle to nothing. it would start out about 3,000 rpm so thats a little bit lower than without the exhaust...

im thinking of parting this thing out...

any ideas before i dump the parts on ebay?

d

 

Need some more info. What type of exhaust, 4-1 or 4-2? What type of air filter, stock or other? Did you have all the air box boots in and tight as well as the intake boots tight? What size main jets?
You stated that the bike was running rich and would bog down with the slightest throttle increase. That is more indicative of a lean mix than rich. So I would do this: screw all pilot mixture screws in and back out to 2.5 turns. Make sure all boots are tight and that the exhaust is tight also. See if it cranks like that with a little choke.

 

factory exhaust
UNI foam air filter
all air box boots and intake boots factory tight
main jets are proper as far as Rick and i can tell
all pilot mixture screws have been turned to 1.0, 1.5, 2.0, 2.5 and 2.75 turns out at one time or another...

if the bike was running lean, the plugs would be gray and not soot black would they not?

d

 

are the floats adjusted correctly?

quick way to check for leaky float valves:

take intake boots off. apply fuel to carbs (leave petcock on PRI). watch through the carb intakes and see if fuel starts puddling around the needles and/or gushing out.

you may have to use a thin wooden dowel to raise the diaphragms so you can see better.

if you have a leaky float valve or a sticky float, your carbs will run very rich. this happened to my 550.

are all 4 plugs equally sooty?

 

Put it to the Propane Gas Test. See if it will FIRE with your Propane Torch Gas being the Fuel Supply.

Turn on the Gas and let the Gas from the unlit torch enter the Airbox Inlet.

If the Bike FIRES on the Propane ... the Problem is Fuel Supply
If it don't ... there's something else we need to look for.

Somebody who has the 550 Manual needs to supply us with the Pilot Mixture Factory Preset for 550.

In the mean time ... do the Propane Test and see if she'll run!

 

Y'all will LOVE this. . .taken from page 137 of the yamaha xj 550 service, repair and maintenance manual. . .
"Caution. When cleaning the carburetor assembly, do not turn the pilot screw, as it has been preset at the factory. Changing the basic setting will actually decrease engine performance. Carburetor adjustments which can be performed are described in Chapter Three."

Chapter Three states:
"Carburetor Idle Mixture. Idle mixture is preset at the factory and it is (in angry looking italics) not to be reset

Hopefully I'll be able to find something a little more helpful for ya. Till then don't give up hope!

Trev

 

Sorry RickCoMatic, the 550 manual ( courtesy of the XJCD ) only states "preset", here's the clip......

 

Oh, no ... not that!

OMG ... We are the ones responsible for Global Warming.

Look ... if that is the case ... could everybody tweak a little-bit richer. I'd like to have it in the High 50's ~ Low 60's this winter.

I'll be going to Prison soon. I removed that Label from the mattress and I did it on purpose.

 

This may be a shot in the dark, but is there a possibility of excessive backpressure (ie something clogging the exhaust) or maybe something clogging the snorkel for the air cleaner housing? Just asking 'cause that's what you said you were wrenching on before the non-running problem.

Nevermind, that's a stupid question.

 

I'll make a trip over to the Dealer and consult with the guy I know over there who will tell me:
"It's the Carbs. It's always the Carbs!"

The Pilot Jets are what I suspect. You'll have to see if the New Ones you have in there ... are the same as the ones in the Parts Carbs you'll be getting when the box arrives.

I doubt if that's what it is ... I think, because it was running at High Rev's not long ago ... that it's a matter of getting the Pilot Mixture Screws where they belong!

 

does it start with starter ether? that would be a good check to see if it is fuel delivery, weak spark, etc.

 

i havent tried the starter fluid yet...

after i swapped arcin'-pins (oklahoma for spark plug) i didnt have time to run back out for a can of ether...

ill try the propane thing if i can find a bottle at the house. otherwise its Murray's on the way home from work tomorrow...

i know the collector is clear because i knocked the old gaskets thru it when i replaced them and when it DOES run, there isnt any indication its not flowing thru the mufflers...

has anyone any thoughts on the rich/lean mixture ive got? i say rich but others have said lean. i know that motorcycles are a beast unto themselves but when my buddy's hot rod was out of NO2 if the system was still armed, it would bog down when you hit the fog switch. that was because the mixture was too RICH (i.e. too much gas and not enough oxygen due to an empty nitrous bottle). also in the cessna i fly, the engine runs much better as i lean the mixture. maybe the yamaha engine is different i dont know...

d

d

 

my little yamaha two stroke would do the same thing. It would run stronger when I leaned it out and then (if I went too much) get a distinctive sound to it and let me know to bring it back. And it would run like crap and bog down if it were too rich. That's about the extent of my hands on knowledge though.

Good luck!

 

should i get it started, do i bring the idle down to 1,200 or so with the idle screw BEFORE i start working the pilot screws?

i HAVE been lowering the idle because i dont feel comfortable running the bike at 6,000 rpm before messing with the mixture...

d

 

Personally I think Ltdave deserve the persistance award. The man will simply NOT admit defeat.... sorta like.. "I will land this plane gently on the runway even though there is a 25 knot gusting crosswind... if it kills me."

hehe

 

Yes, lower the idle. If the butterflies are too far open you will be getting too much main and won't have much luck with the idle jets anyhow.

 

Clymer Manual, page 244, Table 11 - Pilot screw setting for 1984 XJ550 UK model is 2 1/2 turns. That is probably a good place to start.

 

There's the stat, LT ...
Bottomm those Screws and bring 'em out 2-1/2 Turns.
That ought to get you close to being able to get the bike running on the Pilot Circuit.
If it's still RICH ... turn 'em in a few degrees ... to something like ... 2-1/4 or a little less.
Then, you tweak for Best Idle and go from there.

 

The Pilot Jets you`got new and we put-in are the Multi-ported Pilot Jets.
They probably ... I can't say for sure ... run Hotter than the Stock ones.

You should turn the Pilot Mixture Screws IN to 1-1/2 Turns Out.
With a charged-up battery.

Give it Enrichment and get it running. Hold the Throttles Open if you have to to get it warmed-up.

Turn the No-1 Pilot Screw out until that Cylinder increases the RPM
(I don't know how far ... I suspect more than two)

Once you get the No-1 Cylinder "Hitting"
Kill it.
Index the No-1 and see what the Value is from Bottom.
Set 2, 3 and 4 to that setting where the Bike is firing on the Pilot Circuit.
Then, continue to bring out 1 listening for the rpm's to rise.

Kill it.
Reset the count of where 1 is on 2,3,&4

Now you can play with it.
Backfire is Lean
Bogging-out is Rich

Tweak it in.

 

any word? If it is running pig-rich and fouling plugs, it is probably a float level issue. I had this issue on one of my carbs when I got the bike.