81 xj550, lots of trouble.

Hello everybody,

I have a few questions for you seasoned veterans about my 81xj550, I will list them as follows and hopefully somebody can help:

1. Sometimes start button will not work and have to turn key off and turn key back on again for it to work, and recently it has not been starting at all and says oil level is low?

2. Bike will only run with the choke on, which is indicating a vacuum leak correct?

3. Does anybody know what the spark plug gap should be?

4. Also, I recently replaced the intake boots with new ones, and I thought it would help but did not. I was messing around yesterday and finally figured out that when I spray starting fluid towards the engine side of the carbs, it revs up! So, I am sucking air somewhere, question is where could it be leaking besides the intake boots?

Thats about it right now, some help would be greatly appreciated and if your in the Milwaukee area beer would be traded for good advice.

thanks,
Nick

 

1. "Low oil" light is normal if bike doesn't start. This is generally part of a set of symptoms connected with either a flat battery, or a fusebox/solenoid/wiring issue. The "low oil" lamp in and of itself is not a great concern (as long as you have oil in the bike.)

2. No, it means you need to clean and service the carbs. See #4.

3. 0.6mm~0.7mm; or .024"~.028" since these bikes tend to be hard on plugs, I usually go with .025" since they only get wider.

4. Throttle shaft seals. See #2.

Oil level is checked with the bike on the CENTERSTAND and the motor having been off for at least 10 minutes. Level should be above the top line but with a slight bubble at the top. You will not see oil in the sight glass if the bike is on the sidestand.

Save me a whole lot of typing and "cut and pasting" and read: http://xjbikes.com/Forums/viewtopic/t=32762.html (another new 550 owner.)

Welcome aboard; hope this helps. Before anything else: REAR BRAKE http://xjbikes.com/Forums/viewtopic/t=15874.html then get after the fusebox and install an inline fuel filter.

 

Thank you for the info, I am going to start going through the list. I noticed that the oil light only comes on when you push the start button. For experimental reasons I just have been arcing the solenoid which is probably not a good idea for long term use but I want to ride this beast.

 

1. Your battery is weak. As soon as the bike tries to fire, the headlamp will kick in and suck up the rest of the juice needed to finish ignition. turning the key off turns the light off and resets everything so you can try again.

2. No, it doesn't indicate a vacuum leak. It indicates that your carbs are plugged and only running on the enricher circuit.

3. Don't know

4. Make sure that you put the black caps back on the intake boots. Make sure that they are seated tight against the manifold. make sure that the clamps around the carb ends are snug. Make sure that the airbox to carb boots are ON the fronts of the carbs ALL the way and that the clamps are secure and snug. If you're still getting a vacuum leak, my bet is the throttle-shaft seals.

Dave

 

Yeah I am leaning towards just bringing the carbs somewhere to get rebuilt. Thank you for the heads up and I put the battery on the charger so we will see if it does that later. Thanks again

Nick

 

Don't be trying to "ride this beast" until you've inspected the rear brake shoes for delamination, and at least replaced the brake fluid up front.

Quite honestly you should attend to everything on the list before trying to ride it otherwise you'll only be riding it in short spurts anyway.

 

Rebuild the carbs yourself and save a lot of money. It isn't that difficult. The writeups on here are excellent too. Bigfitz is the master of the XJ550 on here. Any help he gives you, you can believe he is right.

 

Test your starter circuit in a methodical manner until you find and eliminate the fault (there may be more than one) ...

http://www.xjbikes.com/Forums/viewtopic/t=32483.html

Provided the level is ok, the oil lamp should go off when you release the starter button whether the engine starts or not ...

http://www.xjbikes.com/Forums/viewtopic/t=32609.html

Then tune up per the excellent information on this site, check your running gear as suggested, tyres, brakes, etc. and enjoy !!

 

Flat battery was the issue, charged it up and it fired. Next step is follow that bench syncing process that is one this site, then seal up the boots with some rtv. I just got new boots last year. Then we will see what happens. Hopefully it will work, I am being optimistic but the carbs probably need a rebuild.

 

1. battery-- we told you so

2. carbs - we're telling you they DO need to be redone, not Probably do. And yes, you CAN do it yourself. I refused for the longest time to believe that. I finally tore a set apart COMPLETELY and rebuilt the rack. Now I have NO fear of these carbs. I still can't believe how simple they really are. YOU can, too.

dave

 

Tune up in a methodical manner and think about the big picture as you work through the process.

Internal combustion engines only need three things to run, compression, ignition and fuel but they need all three. Address them in that order or you will chase your tail.

I've lost count of how many apprentices I've watched trying to tune the miss out of an engine by fiddling with mixture when it was a crook plug lead or a riding valve. After a while they finally figure out the logical order of things and realize that engines too follow the laws of physics.

Compression test ... set the valves clearances then test wet and dry, only when you have high and balanced compression, move on.

Ignition test ... make sure you have good reliable spark on all 4 lungs, then move on.

Now you KNOW it's neither compression or ignition, any remaining issue has to be fuel, so give it the RIGHT amount and it will run ... sweet as.

Fuel variables ... fuel quality, tank cleanliness, petcock issues, carb issues, manifold leaks, etc, etc. Check them all until it runs the way the engineers intended ... like a startled gazelle !

 

Just a quick note regarding the carbs.

You Can Do It!!!!!!!

I also approached the task with a small amount of hesitation. The information on this site, along with moral support, will get you through with NO PROBLEMS!!!

Be organized(I used muffin tins) - take pictures - go slow - be very detailed - patience will be rewarded.

I tore mine down to the point where I had the bodies ultrasonically cleaned. In the end I looked back and said "WOW, That was easy!!!". Now I have absolutely no fear of tackling any set of carbs out there - Very Basic - Very Simple - Time Consuming!!!

Best of luck

Stephen

 

Well you guys are pretty persuasive! I am going to try and tackle it. I am still waiting for my clymer in the mail so I was wondering if there is a valve clearance check guide on here. What kits did you use and are there any rebuild guides on here? Also, any other suggestions while I have the carbs all taken apart?

 

These guys on this website are great, and the information here is correct.
I just did my 82 XJ550 with the same symptoms and found the idle circuits and the emulsion tubes were all gummed up. It was a far more time consuming task than it was difficult after I read up on rebuilding. Its so easy a caveman can do it. I used kits from the oldbikebarn, and after reinstalling the carbs it fired up on about the second revolution. I was so excited I put it together and rode it. Last night I checked my valve clearances and they are all in, so next I'm syncing carbs and riding some more! Follow the order these guys dictate and it'll run good for you. Mine isn't even dialed in yet, and it will pull the front end off the ground easily! (and I'm dam near 50 years old!) 8)

 

Do you guys suggest getting one of those acid dunk jugs or just paying to get the body cleaned?

Thanks!
nick

 

There's a variety of readily available products for carb cleaning. I have had success with degreasing then simply soaking in white vinegar, plenty of people on this forum have boiled them in lemon juice with similar results. I guess the mild acid effect is what does the cleaning. Smells a bit either way but you'll get a pretty good result with just simple cleaning methods.

Read this before you start ....

http://www.xjbikes.com/Forums/viewtopic/t=14692.html

If you want to make them look pretty you can take them somewhere for an acid dip, have them wet glass beaded or set up your own soda blast. For now I recommend you just get them clean and running right, then worry about making them look nice next time around.

 

The carbs are quite simple really, once you get them off the bike of course. I soaked mine in boiling water then hit every hole and crevice with brake cleaner. I had a mechanic tell me to never use carburetor cleaner unless you 100% disassemble the carbs and remove any rubber o rings as carb cleaner eats away at these very quickly, whereas brake cleaner does not.

Mine only idled with the choke half open and quite rich, after doing this simple cleaning, it idled perfect with the choke closed and had a massive boost in power at all RPM ranges.

You can get the bike idling great with only about 1 hour or so of work doing it yourself.

 

Perhaps, that will depend very much on what's wrong with them. The best way to tackle it is to fully dismantle them, thoroughly clean them and rebuild them replacing all necessary parts as you go. You can do it now or do it later but you WILL end up doing it.

 

Exactly. You WILL end up doing everything it's the only way you'll succeed. How long it takes you to realize that and quit "stabbing" at it is up to you.

A few important points:

-removing the butterflies and throttle shafts on Milkunis requires SURGERY. It may or may not be necessary, depending on the condition of the throttle shaft seals. DO NOT dunk or submerge the carbs in anything, or you WILL be replacing the throttle shaft seals too.

-you will need to vacuum sync the carbs once you're done cleaning them and setting the float levels, etc. You cannot do this if the valve clearances are out of spec. Valve clearance check and adjust: http://xjbikes.com/Forums/viewtopic/t=14827.html Addendum: http://xjbikes.com/Forums/viewtopic/t=29209.html

Get the valves in spec and run compression tests as has been recommended; be sure you're not putting a whole lot of effort into trying to make a motor with a soggy cylinder or two run right.

 

Is there a carb kit that you guys would recommend getting? I saw a set of four on ebay for 69 bucks and it came with o rings, bowl gasket, and float valve assembly. That seemed pretty decent, I found a k&l kit for 22 a piece and they have jets too. I am not too sure on which ones to buy.

 

I liked the K&L kits. They have the inlet screens on the needle seats. Not all kits have these. They keep the trash out.

 

Ok, so I took the carbs apart today and it was pretty eye opening.

There were lots of little gooey chunks and the screens were covered in a green silicone type substance. I took the air mixture screws out and one o-ring was broke in half and the other 3 were crispy pancakes. Also, 1 of the washers was replaced with a bigger washer

I have a massive o-ring kit so I am just going to clean everything up and put it back together and see what happens. IF it doesn't work, it was good practice and I am pretty confident not.

The only bad thing that happened was one of the float pins got marred up while taking it out. Is it possible to get a new one?

So I have a couple questions.

1. Would a hardware store carry washers the size of the air mixture ones? and if not where could I obtain them? Also, I could not tell if the washer went in first or the o-ring.

2. Should I just get the kits or attempt the unpredictable and put them together? I have an o-ring kit with all the right sizes.

4. Does anyone know where to get the kit with the screens on the jet and what are the pros and cons of the screens themselves?

5. Also, I need a float pin so, does anybody know where to get one of those?

You guys are awesome and thanks for the boost of confidence, I am pretty proud i even got them taken apart this far.

Thanks,
Nick

 

Don't use parts from the hardware store, an o-ring kit or anywhere else. Go to the top right corner of the page and click on the XJ4ever link and buy the right parts for the job from chacal. He's got everything you could ever possibly need right there in his catalog, they are the right bits, at a fair price.

Or you can put it back together with dodgy bits and be back in a week saying it didn't work.

 

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