Yamaha XJ 550 4V8 Trouble Starting Motorcycle (Philipp's ongoing troubleshoot)

Hey there people,

Just a quick introduction before I get to the actual dead end I'm finding myself at:

My name's Philipp, I recently bought a rather neglected Yamaha XJ 550 and I'm currently in the process of breathing some life back into it. Even though it's been sitting for only a year or so, the previous owner did not treat his motorcycle with the same tender love as I'm used to, so there are a lot of small things to repair/replace.

Also, as a kind of quick disclaimer: I'm actually German, but because the German equivalent of this XJ forum is dead and I can't even register because I'd have to be accepted by an administrator ( ), I'm turning towards you guys for help. Since English is not my mother tongue and I haven't figured out all the English technical lingo yet, I'd appreciate if you could, should motorcycle specific terminology arise, use the most general expression for it so I can look up the German equivalent. Also, please try to spare me with acronyms, I'd only have to waste your time even more by asking you to elaborate


So, now that that's done, here's where I'm at:

The foremost problem (of which I'm sure there'll be plenty more for you guys to enjoy helping me with ) is that the engine just won't start. I can have the starter motor turn the engine as much as I want (in intervals of course, wouldn't wanna melt the starter motor), it just won't fire.

Now, even when I'm turning the engine until the battery runs out of juice, the spark plugs stay dry as bones. To me, that means that the fuel/air mixture doesn't find its way into the cylinders, eh?
I can only see two reasons for that:

1. There's a vacuum issue between the cylinders and the carbs that prevents the gas to be sucked into the combustion chamber
2. Something with valves and stuff.

I feel like this is the point where I should mention that I did work on run-down motorcycles before, but I never had to deal with valves and valve adjustment. I know that there are intake and exhaust valves, and if I understand it correctly, misadjusted intake valves could be a reason why there's no fuel going to the combustion chamber even if all other criteria for a successful start are met. Does that sound about right?

I am going to measure valve clearences as soon as I can and get back to you with the results, but I want to get as much input about possible issues as I can, so that I can check them off the list.

A few other things I already tried/took into consideration:

- Disconnected air filter box from carbs
- Tested all spark plugs for spark, all there (even though I can't evaluate if the spark is 'good' or 'strong' enough for the engine to fire)
- Even when using... starting spray (proper expression?) while turning the engine, there's not even the slightest pop
- Pulled and cleaned the carbs twice by hand (with the help of break cleaner) and replaced the jets
- Fresh fuel is going from the tank through a filter to the carb bowls without a problem, so gas availability shouldn't be a problem
- intake manifolds aren't the prettiest, but nearly not hard/brittle enough for vacuum leaks
- The engine is turning; after pulling the spark plugs, you can feel the air pressuring out from all four spark plug holes while turning the engine
- Didn't have the chance to check compression yet, but I ordered one of those testers and I'm going to update you once I know more. Still, as far as I know, even bad compression should be enough to at least make the engine cough with the help of starting spray
- I ordered an ultrasonic cleaner (always wanted to have one, found a 10l cleaner for a bit over 100€ ), I will clean the carbs again, this time properly


I hope that gives you a general overview about my situation. I was trying extensively to look up similar problems online, but I couldn't quite find any other approaches as the ones already mentioned.
Again, the only possibilities I was able to come up with are vacuum leaks, possibly a weak compression, clogged carbs or troubles with valve adjustments.

Are there any other things that come to your mind that could cause this/ that I should try?


Thank you all in advance for taking the time and for actually reading through this all, I know it's all rather unorganized but it's hard getting all the things that I already tried and the things that I found online in order

If there's anything else you need to know, please do ask. Also, I'm always happy to learn, so if there are any misconceptions about all this on my end, please feel free to correct me!


Cheers and Danke,


Philipp

 

y ou own a 82 XJ550 euro version.

first thing to test is your battery. do a voltage drop test. hook volt meter to battery and crank the starter if voltage drops below 10 volts bike will not start. Transistor Controled Ignition (TCI) needs 10 volts to fire ignition.

ohm out your ignition system Ignition coils , spark plug caps (caps unscrew from plug wires) and pick up coils.

the ends of the spark plug wire may be corroded so trim 6 mm off each end.
spark plug caps may have a screw inside where spark plug goes tighten it if needed.


do the spark plugs get wet when you try to start bike?

it should fire with starting fluid or at least back fire.

do you have glass fuses? you should replace with blade style fuse block or inline fuses.

enrichment circuit may be clogged and the wells in the carb bowls that the tube goes into if you are not getting any fuel

 

intake manifolds can be coated with Black RTV fuel resistant gasket sealer. this will eliminate them as a issue

 

Yes, re do the battery health, first, even a GOOD XJ electrical system can have a somewhat 'weak' spark.....

You could even try a truck/car battery.....repalce your XJ battery leads temporarily with 'jump start' leads from a known good ( heavy duty) battery....I always take my XJ battery out of the equation completely,( disconnect leads) to use this method, then use 'jumper cables' from the car directly to the disconnected leads + and -

Are you able to see ANY sparks, when grounding out the plugs to the head ( night is best, obviously)

It does sound like you still have NO fuel getting though though, although with copious amounts of starting fluid, you should at least get a 'backfire' ( its not really a backfire, but you know what I mean)

Are you able to 'drain' your carburetor float bowls ( screws) to make sure you have gas/petrol in them??

 

Hey guys,

Thanks for the input.
I tested my batterie, after fully charging it and putting it in, it breaks down to about 9,5 volts while turning the engine for an extended period of time (about 7-9 sec).
It might be worth buying a new one, but I know that my current battery must be working because a friend of mine put that same battery in his bike, and that one fires.

The ignition coils, pick up coils and spark plugs along with the caps have been replaced, and there is a visible spark coming off of all spark plugs when grounding them to the cylinder head.

Even if the spark wasn't strong enough, as I said before, the spark plugs remain dry even after cranking the engine for a long time. They should be soaking wet eh? I feel like that's the bigger problem I gotta tackle first.

The float bowls definitely get gas, I checked that.

I'm going to use my cars' battery to take my bikes battery out of the equation, just to get that off the list.

I hope I can work on the bike today, I'll get back to you with the results.

Any other things that come to mind?

 

550 is harder to start with a low battery. if battery works well in another bike. you want to clean ground cable from battery to motor and frame.
clean the positive cables from battery to solenoid and to starter. your starter may be drawing to many amps. starter may need to be rebuilt.

did you bench sync the carbs when you cleaned them?
set mixture screws to 2-1/2 turns up from soft bottom?
did you check the wet fuel level?

Setting the fuel levels

dry spark plugs


Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

 

Sorry for the late reply.

I have yet to try starting the motor with a car battery attached, but I did manage to check valve clearances. Here's what I found:

According to the manual, Intake Clearance should be 0.11 - 0.15 and Exhaust Clearance should be 0.16 - 0.20.

Cylinder: 1 2 3 4
IN 0.04 0.05 0.05 0.03
EX 0.06 0.07 0.06 0.04

All valves are obiously way too tight, so that's something I need to address. The question is though: Could that be a reason for why the bike won't start, even when spraying a bit of brake cleaner into the intake (cylinder side) ?

@ kerriskandiesinc : I'm gonna try that with my car's battery, but I somehow want to address the issue of the dry combustion chamber first...

@ XJ550H : I didn't sync the carbs, I'm gonna have to take care of that as well at some point. Also, I might be horribly wrong, but... is it possible that my set of carbs doesn't have any mixture screws?

 

Yes, if those valve clearances are correct, as posted that could make her a lot harder to start......basically, she can't breathe properly

 

I'm actually glad to hear it. I feared it might have been something worse.

By the way, I forgot to mention that I checked the compression. It's about 95-110 psi for all cylinders. Not great, but not bad enough for the engine not to fire. Adjusting the valves should improve the compression, right?

There's a special tool in order to get the current shims out, right?

 

compression should go up with new shims. 10 psi is a nice tight spread between cylinders
we have a thread on shim check and replacement there is the tool way the wire tie way and house wire way

Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

the tool that is sold needs a little grinding on the sides to fit properly unless you find a yamaha brand tool

 

Amazing guide, thanks a lot.


I still can't quite wrap my head around it. With a very tight fit like that, shouldn't the lobes open the valves even more than they're supposed to? If so, then why is there no fuel going through?

 

open more and maybe not letting them close enough

 

Alright I'm gonna try adjusting the valve clearances, it's gonna take me a few days to get all the materials.

 

Fuel might be getting sucked right back out!!, before compression/spark has a chance......you still might have other problems, but, 'fix' one at a time, and then see how she responds

 

Will do, thanks!

 

Just lurking some threads trying to figure out my own starting problem. How'd it go with the valve adjustment? Did that help with starting?

 

I can't tell yet.

I adjusted the valve clearances and tried turning the engine over, but my battery was pretty dead, it was cold outside and there was no gas in the carbs, only some starting fluid fume.

I'm gonna try it properly some time next week and get back to you with the results.

 

on your carbs there are small discs covering the screws have mixture screws up on top front of carb
cut away of carbs
http://www.xj4ever.com/inside your carbs.pdf

 

also can be seen in this link for maxim x carbs
Cleaning your Mikuni carbs

screw driver is in the hole

 

Philippe,
The site won't let me respond to you in German, but I'll try using PM.

 

One thing you should try , turn the idle knob in several turns and see if it will start or at least chug, if it is not pushing against the butterfly plates will not open , hence no fuel into cylinder. You have stated you were trying brake cleaner to try to start , starting fluid is best to use. You can also do a bench synch, I take two business cards cut in half , put one piece under each butterfly plates , try pulling card out with slide drag if to much or not enough starting at carb 1 turn synch screw in or out till you get a slight drag ,move on to carb 2 , and carb 4 , carb 3 is controlled with the idle knob . If you do this right , hold carb rack up to a strong light you will see a slight crescent moon at bottom of butter fly plate. From what you have stated to me it is fuel related problem , if you adjusted valve clearance that will help . Good luck.

 

Hey guys,

After a rather long hiatus I finally got back to getting the bike ready for the season - as bad as it is, Corona afforded me plenty of time to work on the bike.

After going over the carbs multiple times and having figured out all the electronics, I finally got the bike to start.
Unfortunately, it revs really high right from the start, around 3000 rpm.
The high revs are consistent, and I can't make out any air leaks (I replaced all the rubbers), and I doubt it's got to do with any clogging in the carbs since I was very minute in cleaning them

@XJ550H I found the mixture screws, but I'm guessing either I or the previous owner screwed up the setting.
What's the standard amount of turns for these, and do they influence idle speed?

 

Okay I just figured it out, 3 minutes after posting this.
Turns out, clever me failed to notice that the idle screw was turned in way too high.

Concerning the mixture screw, I'd still love to know how many turns they're supposed to be out.

Is there any way to post videos in this forum?
I'm noticing a metallic, rattle-y noise coming from the engine, as if a key is touching the vibrating frame.
While the bike is running, the oil level in the lower half between the two lines on the little oil screen below the transmission, so I'm guessing there's enough of that.
The bike hasn't run in well over two years, so maybe the noise is gonna stop once it's all lubed?

I was also thinking valve clearances. I just checked those, but that was before the bike even fired up for the first time, so I'm not sure how reliable those measurements were.

Any other suggestions?

Cheers

 

-Did you ever do a running sync?

Check your collector box heat shields....they can get loose and start to rattle. Also, look to see if one of the relay rubber mounts has broken.if so, it may be hanging down and vibrating against something.

 

Thanks, I will check that.

Here's a video of the rattling, it can be heard rather well around 25s

 

Did you replace shims to get correct clearances yet? ( did you do you clearance measurements with a COLD engine)

Did you do a running sync yet? Sounds like it’s not synced yet....

and from my view, it sounds like a loose cam chain too.... have you done anything with the cam chain adjuster?

also just as an aside, does the sound go away when you shift into gear and let the clutch out?

 

Thanks a lot for the input.

Yeah I already replaced the shims to have the valve clearances up to specifications, but I did that with a cold engine. I knew I would have to redo that at some point, but I wanted to take closed valves out of the equation.

I did not yet sync the carbs at all, I'm pretty sure that's why it's running on the rough side.

Ew, cam chain problems would suck. Does the XJ 550 have a spring loaded adjuster?

Concerning your suggestion with the gear, I'm gonna check that tomorrow, I didn't check that yet.

As a side note, I noticed that there's fuel dripping out of mufflers on the joints on both sides, so I'm assuming it's running fiercly rich. Is there any smart way of properly tuning the carbs without any special equipment?

 

What do your sparks plugs show?

 

mixture screws set at 2-1/2 to 3 turns from soft bottom.

the 550 has a springloaded cam chain tensioner it is under the carbs a bolt with a lock nut.
you remove the crank side cover left side of bike turn that square nut counter clockwise untill the pointer points at the C mark

losen the lock nut then losen the bolt
you should hear the adjuster pop forward if it was real loose


retorque bolt to spec torque nut to spec replace side cover your done


with oil when bikeis on center stand add oil an ounce at a time untill there is a little bubble left at the top of sight glass and set rpm to 1100rpm this will help quite down the primary chain

 

I’m glad to hear you did them clearances already, and YES, you DO do it when the bike is COLD. So you should be good there, as long as you did it right.

 

@Huntchuks I'm gonna check them later, I'd be surprised if they weren't pitch black. I'm running the bike off a rudamentary gas tank and I could watch the bottle emptying, that's how much gas it was chugging. Are there any other reasons why the bike might spit out unburnt gas?

@XJ550H Great, thanks for the walkthrough. I'm gonna do that later. Concerning the oil, am I supposed to top off oil while the bike is running? I just wanna be careful as to not overdo it with the oil.

@hogfiddles Oh that's interesting, I thought you were supposed to adjust valve clearances with a warm engine. Oh well, I take it


Down the road I want to replace the clutch plates and springs. A shop stated on the most recent service report that the clutch was slipping or not disengaging properly.
Will I have to drain the oil before opening the clutch case, or won't there be any oil coming out while the bike is on the side stand?

 

Bike sounds ok to me but cam chain tensioner adjustment won't hurt (easy too)

Oil level check when engine off and 'rested' 5 minutes.

cheers

 

Okay so I did the cam chain tensioner adjustment, though I did not hear it click at all, and the engine still sounds the same, running.

I'm having trouble starting without starting spray after it's been sitting for a while.
Also, as I mentioned before, I feel like it's eating gas like crazy. I'm flooding the bowls and keep a good bit of fuel in the fuel filter, and after having it run for ~ 30-40s the fuel filter is empty. Not sure if that's normal for that bike.

Engaging the clutch and going into first gear didn't change anything about the sound either.

The spark plugs are not at all what I expected, they're pretty white with a tinge of brown/yellow.

There's also gas still dripping out where the mufflers meet the heat shields after it ran for a while.

 

You stated you have cleaned the carbs well but did you make sure you cleared the enrichment circuit jets pressed deep into the side of the float bowls?

 

I did, I knew I had to look out for them.
Also, playing with the choke does not help.

Does the carb mixture setting affect the cold start and idling of the engine or does it only come into effect when riding?

 

Mixture screw primarily affect the IDLE mix. The enricher enrichens the fuel mixture for cold starts.

once you’re rolling on the throttle you are rolling on to the main jet... and THAT mix is residually influenced by everything else

 

Gottcha, thanks for clearing that up for me. So I'm gonna set the fuel mixture screws at 2 1/2 - 3 turns out, right?

I took the carbs out once more, just to make doubly sure the enrichment circuits were clean.
While I'm at it, I'm also gonna do the bench sync that you advised, @hogfiddles .

 

Yeah, about there for a starting point, then colortune and running sync. The 550 may end up more like 4- 4.5 turns out, too. The 550 is finickier than the 650/750’s

 

So there's no 'home made' alternative for fine tuning the mixture without colortune?

 

There is: ride the bike, pull the plugs, adjust, ride the bike, pull the plugs, adjust...you’ll never get it quite right though.

Trust me: I didn’t want to buy the tool because it was $70, but man does it make it easier diagnosing problems and if you ever go to sell your bike, sell the tools along with it and get your investment back. I just bought the tool 2 weeks ago through chacal and it’s helping me get my rich run I g bike back on track. (Morgan Carbtune Pro helps too but that’s easier to make but well worth the $117)

 

As far as I'm aware the colour tune thing is only relevant for idle. Not sure if ut has significant effects elsewhere. It's not a big issue for me, I set the screws to 2.5 and left them. I felt balancing was more important along with valve clearances.

 

Okay I bench synced the carbs (they seemed pretty sync to beginn with) and cleaned them, and now it's firing right up.



But I still feel like it's running kinda rough, there's still some kind of clattering noise



Any more input concerning that? Maybe the idle speed is just a tiny bit too low? I'd say it's slighty below 1100 rpm

 

Little update:

The bike's firing up nicely now, even though only with choke. If I take the choke off too early, it bogs down and dies. After having it run for ~30-40s, I can take off the choke and it's idling steadily at 1100 rpm. I'd say that's normal.

The mufflers are still leaking fuel though. Both have little rust holes right at the clamps where the mufflers meet the collector box, so that's where it's coming out. What I'm confused about though is the amount - I don't think that much unburnt gas is supposed to be delivered to the mufflers.
Any thoughts?

I'm also about to make a little test run as soon as I bled the new steel-braided lines, but first I absolutely wanna make sure both the wheels and also the chain are aligned as they're supposed to be. I had both tires off and installed a new chain. From strictly eyeballing it I'd say it's fine, but I don't wanna risk anything.
Do you guys have any input on how to properly do that?

Cheers

 

This is what a few rounds up and down the street and quite a bit of idling look like (all straight out of cylinders without cleaning)

Cylinder 1: https://www.directupload.net/file/d/5809/fjoefr7i_jpg.htm

Cylinder 2: https://www.directupload.net/file/d/5809/9ff5sgvm_jpg.htm

Cylinder 3: https://www.directupload.net/file/d/5809/uvui25dj_jpg.htm

Cylinder 4: https://www.directupload.net/file/d/5809/rjd54jaj_jpg.htm

It's probably running rich, but it's also a bit more black than I'd imagined.
Does this look ok to you?

 

1200 rpm is better fot the 550 it keeps the primary chain tensioned and reduces the slap.

mufflers have a little drain hole at bottom often confused with a rust hole.

are you sure it is fuel?
if it is you have an issue with your carbs wet fuel level or float needle s not sealing

 

Got it, will adjust the ilde then.

Concerning the mufflers, I'll have to take a close look wether it's a rust hole or a drain hole. Given that it's on both side in exactly the same spot, drain holes would make more sense.
I would suppose it's fuel - when starting the bike after having in sit for a few days, there's a few splash spots under the mufflers as if one had flung a wet paint brush, both that and the big spots under the supposed drain holes evaporate fairly quickly though.
If there was a problem with float needles not sealing etc, wouldn't I notice that in other places too? Like overflowing carbs/ gas coming out of the overflow, or maybe a drenched air filter box?

Cheers

 

Plugs look ok but really you need to take a look after a decent run and the motor is good an hot. As said exhaust drips are more likley water than fuel. Check your mpg (or km/l) after a ru if it's close to 45 mpg (UK galls) you're doing OK.

 

It may be just water. Water is a biproduct of combustion. Take a tissue and soak up the mystery fluid and try to light it with a match. You will know quickly if it is gas or water.

 

Or smell it

 

Cheers guys.

I tried smelling it, it doesn't necessarily smell like gas, but it has the yellow-ish color to it. I'm just gonna ignite it, see how it goes.

I pretty much put the bike together completely now. There's just a few things I would like to run by you before I'm gonna have to deal with licensing the bike with the German Technical Inspection Association.

1) I completely overhauled the break system and bled the new steel-braided lines, there is not a single air bubble coming out. It does break nicely, but only after half an inch or so of pulling the lever. The real breaking force only kicks in when the break lever is almost completely in. There are no leaks, and all the lines are bled. Is there a way to 'tighten' the break lever so the force sets in earlier?

2) When the bike is mounted on the center stand, and I spin the back wheel (to lube the chain for example), at a certain point during the rotation of the wheel it slighty scrapes the ground. A few degrees further, and there's no friction anymore. We're not talking inches here, just a noticable scraping and then no scraping. That, obviously, can't be good for the bikes stability when riding.
What is causing this, in your opinion? Maybe a worn bearing?

3) As I mentioned before, from strictly eyeballing I'd say the chain seems to be properly aligned. But when turning the back wheel or pushing the bike, there's a slight 'clicking noise' noticable, coming from the chain. I do believe that kind of chain noise is normal, I just wanted you guys to confirm it.

4) As far as electronics go, after tinkering for quite a while I got it all to work, safe for the tach/speedo back lighting, the high beam indicator and the oil pressure light. The wiring diagramm in my repair manual was a vital help, but after checking all the cables for continuity, I can't seem to make out why those three things are not working. The bulbs are all fine, and given that literally everything else is working, my guess is that there's just one single thing off.
Do you have an idea what might cause this? Is there a common denominator between the three?


Cheers