HELP bike keeps dying on longer rides

Well I opened it up and this is what it looks like. Not sure how it was supposed to work with it being offset?

 

Yep def can see why this isn’t working…

 

That IS the way that the selector lever is supposed to be..........the 1/4-circle recess allows / directs the fuel flow between 2 adjacent holes (passageways) in the petcock body; 1 of the 2 holes is always the "fuel in from tank" and the other hole that is "connected" by the 1/4-circle recess is either the ON or RES(erve) selector lever position. The straight slot is when the lever is in the PR(ime) position, and it bypasses everything and directs fuel directly from the tank input internal passage to the outlet passage.

It's hard to tell from the first picture but it seems as those the rubber "distribution valve" (the rubber disc thing with 5 holes in it) seems to be deformed?

And I think it's safe to say that starter motor need a full rebuild or replacement.

 

That starter has seen better days that's for sure. I'd look for a replacement as it appears the armature has been cooked.

 

Oh was honestly expecting to see the lever to have been dremmled like I had seen on these forums to bypass the vacuum. Was not expecting the distribution valve to simply be offset… everything else was looking fine, excited to give it a deep clean.

 

I was probably going to try to rebuild it first with a kit from @chacal. I just am trying to strip down all of these problem bits and order everything in a big order hopefully

 

The commutator has been overheated and most likely the adhesive holding the copper bars is compromised, one of the bars on the bottom of pic #2 appears to be standing out further than the others.

 

I will give it a brushing off and upload some pics after work today, thanks for pointing it out

 

Oh boy, this isn’t fixable is it?

 

Sorry no it is not, I knew something was up when I saw the one bar standing proud and the discolored insulation. Yeah time for another starter from Chacal.

 

OUCH

 

Alright another update,
I was able to find a replacement starter on FB that allegedly works. I will be double checking and may rebuild.

I tore into own of the carbs and started checking numbers. Everything matches except the main jet and pilot jet.
Main Jet: 115
Pilot Jet: 32.5
I have stock exhaust and a KN filter, altitude 1000

 

The other three pilot jets aren’t marked, is that normal?

 

Sounds like someone re-jetted it at a previous time, although they went the "wrong way" on the pilot fuel jet (stock size is a #35). Of course this assumes they are actually Mikuni jets, which have a funny little "squares within a square" symbol on them. Un-marked jets = aftermarket, and for some aftermarket jets (like those that come with "power" kits), the inscribed sizes aren't really comparable to stock jet sizes, since the aftermarket manufacturers use their own "sizing" specs.

 

The other pilot jets? should only be the two down in the float bowl, for the 750 they are #120 mains and #40 for the pilots from the factory, I've stepped up to #126 for the mains and #42 pilot. There are two jets under the lid/diaphragm that I don't recall having being addressed on the forum. If they have and place back in the carburetors according to the service manuals they are in the WRONG positions, both the factory and Chiltons manuals have them transposed so you might want to check them out just to make sure.

 

Apologies, by other pilot jets I meant the other three carbs. 1 marked as 32.5 and the other 3 with no markings at all. I checked the one under the diaphragm (I only see one) in one of them and that was size 165 which is the correct number for my 550. I should probably check the other three carbs to be safe. But I will be purchasing Chacal approved jets along with all the other parts I need. Going to do a valve clearance check next and hunt down a welder for my collector box. I should be riding again soon. I also just got a new iPhone and might try my hand at making a video of all the things I fix and check

 

Ok so I put it all back together, paper air filter, stock jets, working starter, rebuilt petcock/gas cap w/ inline fuel filter and vacuum hose attached to third carb boot.

once the fuel worked its way through the carbs I was able to get it running with the choke on but it died once that was off. Currently air mixture screws are 2.75 turns out from bottom.

the question is, do I need to mess with the air mixture screws and the idle knob to be able to run it without choke or am I missing something bigger?

 

short answer: yes. They all work in concert.

 

Thanks for the short answer, I figured since the carbs were working as best as they could that it was unlikely they had a clog somewhere, I took them off the bike, drained them and replaced two jets per section.

sequence of tinkering should be: idle screw until I can idle with the choke off, then color tune and synch the carbs to the engine? Repeat until just a smidge above Bunsen blue and manometer levels are all equal

 

Issues with idling attempted to turn the idle screw clockwise.

I am unsure if my petcock is working properly. It will pass gas when on prime and doesn’t when ON. Which to my understanding means it is working. But as I have been trying to work on the idle problem the fuel doesn’t appear to be filling the line while “ON”

 

Thought it was flow in PRIME but needed a vacuum signal (taken from #3) to actually open the valve in the ON position. I'm running an aftermarket fuel petcock (ON/OFF/RES) as my original was leaking and I didn't have the patience to rebuild it... someday I might as it's still in the bottom drawer.

 

#3 as in carb manifold 3? I thought so too but in my clymer it referred to removing the vacuum hose from the second manifold.

 

I think I may just have to test for leaks on the boot and then take the carbs off and give them a cleaning I took them to church a while ago and replaced all the seals and o rings. Clean the passages with carb cleaner and wire let the jets soak overnight, compressed air all that jazz. Should have just cleaned them before putting them back on!

 

Ok so I took out all the jets and gave them a cleaning with carb cleaner, water, water/pinesol bath in an ultrasonic cleaner. Used an air compressor and small wires to gently clean the passage, same with the carb rack but I did not break it apart. The pinesol/water ultrasonic did cause some of it to rust. I used a wire brush and wd40 on the rusted parts until they moved without sticking or creaking.

petcock looks good since it was off the bike and didn’t leak a drop

I have the air mixtures at 2.5 turns out and the bench synch looked pretty consistent between the 4

I now have the opposite issue!!! I initially had to get it to start on choke but now it doesn’t need that. HOWEVER!! It instantly turns on and revs to 4-5k rpm!!! when I rev the throttle it responds and doesn’t hang but I keep turning out the idle screw and not feeling like it is working too well. It’s possible some of the wd40 was on the carb boots. I had to take them off when I realized I forgot to attach the gas line

 

So I got restless, took the air compressor and sprayed off all the excess wd40 and let the bike run. It came down eventually and now wont idle without the choke.

so either:
1. there was excess wd40 within the system that eventually used itself up
2. I did not readjust the idle knob and it is completely backed out causing the fly’s to be completely closed
3. Air leak somewhere… manifold or throttle shaft seals, both of which have been replaced during this project

more to come later.
I know I am so close to cracking this!!!

 

https://youtube.com/shorts/wap9CuOmXCs?si=-ZDJ1xKu6mw5QIW-

Why is my bike sounding like this?

 

Sounds like an exhaust leak at one of the front ports. Grab a 2-foot length of garden hose or similar and hold one end to your ear while moving the other end around the front pipes & ports with the engine running listening to the crackling and popping sound, it will stand out when you zero in on it.

 

So I had forgotten to tighten the nuts of the exhaust to the head, torqued those to 10n/m as the clymer stated. I will test again tomorrow and update

 

So the bike is definitely not as erratic, still can’t get it to idle with out choke. I plan to turn the mixture screws out a half turn (3 full turns total) and try again tomorrow. I ran into an issue when priming the carbs that gas leaked from the air box. I assume a float must be stuck, I reached in and it was only coming from carb 1. I stopped priming and gave it a couple of whacks with my mallet. Hopefully that fixed it. Bought some starter fluid to test for air leaks as well

 

Ok so carbs are off and currently hooked up to a free flowing source and not leaking gas all over my garage. When I took them off and looked inside number 1 the float was freely moving but the metal wire of the float needle that interacts with the float tang seemed askew so my guess is that was the cause. I took 2500 grit sand paper to the pin that holds the float and the area it passes through just incase it was catching. Feels a lot smoother now and I bent the tang responsible for how far it drops not the one that sets the fuel level. Letting it sit for three hours to make sure it works, then back on it goes.

 

It's the light at then end of the tunnel.........!

 

One thing I've learned about bikes is nothing is as it seems at first and the Yamaha XJ is no exception. I've been around bikes all my life having been on 2-wheels before kindergarten (1975 on a Rupp) and the one thing I've learned is to think outside the box, the service manual is only food for thought. When I picked up my SECA last February it was in a number of milk jug crates and the first thing I bought for this mess was the factory service manual. Lots of pretty diagrams and exploded views but nothing on the church of clean, that one I had to learn on my own the hard way. Every nut & bolt was turned by my hand, every spade connector extracted from its shell and scrubbed with 400 grit wet & dry. I've had Honda Scramblers, a KDX-175 enduro, a KX1000 with flat cams and the big-boy CBx Sport and while they're all Asian made most everything was unique about each of them and you start the learning curve all over again adapting to the brand on the tank. The smallest of details are so easy to overlook in the big picture, missing the little assist wire on the end of the needle is one I've done a few times myself.

Over the past 8000-some miles this year I've split half a dozen carb boots, mashed the bowl gaskets to the point of useless and ended up making my own from gasket material. Had numerous hung floats from trash getting past the chinesium fuel filters and getting stuck between the needle & seat and an enrichment needle rack finger getting bent upwards holding the needle off the seat and driving me nuts trying to balance the carbs. In short it's been an adventure. What I got in return was turn-key reliability with a 1/4 turn of the enrichment lever. It spanks 1200 Harley Sportsters and rides quite well. The only issue I had that got me worried was a partial failure of the TCI module and that was solved with new capacitors and resoldering. I trust this bike to go anywhere without a worry or large collection of spare parts, just light bulbs and a tire repair kit but it didn't come easy and I never once thought about trading up to something else and I'd do it all over again just for the fun of it.

 

Now, I haven’t checked the fuel levels, the mechanic I took it to said he had done that and honestly I didn’t notice it being an issue when I was able to ride it during the whole petcock and wrong jet fiasco that the mechanic did. I had done it myself with the pvc pipe/ clear tube but since I have the carbs off I might as well be triple sure right? Haha

 

Haha, yes you'd better to that! Correct fuel levels are an important part of carb "tuning".

 

Ok glad I checked the levels!
1st carb: 3mm
2nd carb: 7mm
3rd carb: 5mm
4th carb: 4mm

I believe xj550 maxim is 2mm +/- 1mm

 

How do most people measure the fuel of the middle two? I used the bottom part of where the air intake opening is. It was the same distance on the side of carb one and the land marked just mentioned. Figured I could extrapolate that to the middle two

 

If your rack is mounted on a jig and leveled left to right and front to back, you could probably check the level of the center two against the outside two bodies. If in a jig and leveled, why couldn't you just check levels against their own bodies?

 

Well I was under the impression to do it in the middle of the bowl, but like you said if it is level then the corners should be fine. Thanks for the simple logic haha

 

Fuel levels set, bench synch, air screws 2.5 turns, rechecked spark plug gaps and it still isn’t starting. Granted it was probably ~35-40° F in the garage. Got it to start for a second with starter fluid and choke on but it skyrocketed the rpms and I turned off the choke and it died. Double checking the battery I noticed it doesn’t look to have any fluid in it. But when it is plugged into the tender it recharges to the point the light turns green

thinking of just draining the carbs filling the tank with gas. buy a new battery and do an oil change with new filter in spring. Probably too cold to work on it properly right?

 

Honestly I'd work on my bike at 20F if I was that close but then again many question my sanity including myself. When my 2-ltr of Dew freezes over then it's time to call it a day.

Seriously you have to be the judge of when to say when even with the bike. Given the what you've done so far I don't see a reason why it won't run on the carbs if they have the proper level of fuel in the bowls. I'm going to run thru a quick checklist here just to run thru it.

Got fuel coming into the bowls right? Petcock isn't blocked up or anything? From there you've double & triple checked the float levels to the book using some plastic tubing on the bottom drains with the carb rack on the square and level surface? Battery is a suspect in that it's dry and they don't charge well without electrolyte. There's a 50/50 chance it can be saved by refilling with distilled water and properly charging it with a real charger not the Tender. A cold engine will crank slower but if there's enough power to roll it over near the "normal" warm weather speed it should fire as you've confirmed with starting fluid.All the top vacuum ports are covered?
So how are the valve clearances? Intake boots good and not cracked around the edges? Correct coils firing the correct plugs and always receiving power? No intermittent connections right?
I know it all sounds redundant but sometimes a checklist and a few moments can reveal that one gremlin even if it's only the tail.

 

I love a good checklist!

-drained fuel from all bowls
-Clear tubing from petcock to carbs able to fill with gas when primed and not leak when “ON”
-checked float levels a couple times and all were 2mm +/- 1mm. No noticeable gas leaked from airbox when carbs were on prime so no stuck floats I assume.
-I will just buy a new battery, the old one is from 6/22
- ports 1, 3, and 4 all have caps and port 2 has the vacuum tubing which is new.
- valves are all in spec based on my last check earlier this year. Bike hasn’t been ridden since last check.
-Intake boots look fine, no noticeable increase when using propane to check for air leak.

how do I check the last two?

it also probably needs an oil change (might have some gas in it and I don’t see any fluid in the front brake as well. The oil shouldn’t be an issue when starting and getting it to idle right?

 

Gas in the oil won't have any effect on it starting but it surely will on the longevity of the motor. Obviously it will thin the oil A LOT and will wash the oil off the bearing and everything that needs a coating. Change it first. Oil is cheaper than motors or rebuilds.
I have a fuel level question for you..... you wrote that it is "+2/-1 mm". My question is where are you measuring from? The reference point should be the seam between the float bowl and the carburetor body.

 

That seam

 

Yes, that is the place to measure from for your fuel level. I just did not see any mention of where you were measuring from and thought a point of reference would help all of us help you. The battery can also be an issue. The TCI on these bikes will not work when the battery is supplying 10 volts or less. The bike will turn over on the starter but the TCI will not initiate a spark. You said you were going to get a new battery so that should be handled. Have you done anything with the fuse panel? Just checking. A few years ago I replaced mine on a XJ650 RJ and with the new blade fuses I thought I had a new bike it ran so much nicer. Just saying.... Good Luck!

 

I deeply appreciate you asking the background questions! I missed a very simple thing when I first got this bike and it caused me to go on a goose chase for years! I’m hoping the battery is the issue. I took it into batteries plus this summer and the guy said it was great and nothing wrong with it. I now question that assessment after no seeing fluid in the battery haha. I had it attached to the tender religiously and brought it in over the winter. Replacing the fuse box with the blades was one thing that I did.

 

There, we have eliminated some of the possibilities. If/when you get it to run put a voltmeter across the battery terminals and make sure it is not overcharging as well as that could be the reason for no water in the battery. At about 5000 rpm there should be not more that 14.5 to 14.7 volts. Any more than that would boil the battery. These things have a very good, robust charging system and problems with them are usually limited to low charging due to the alternator brushes being worn down. Sometimes a rectifier/regulator will go bad but not common.
Still, as the issues you have previously described it sounds like a fueling issue. That is most common with these bikes. When they are "right" they are really nice and tend to stay that way.... if we don't screw with them too much!

 

Not sure if you have jumper cables? Jumping with a good car batter or stand a lone batter that has good amps is always a great idea. Don't have the vehicle running but us the batter and jumper cable to make sure the bike has good power to help it start.

 

Worn brushes or dirty commutator surfaces (on the alternator rotor) can cause undercharging, but the #1 cause of OVER-charging is corrosion on the wire terminals that lead to the rotor.....corrosion increases resistance, which reduces voltage, and makes the regulator "think" that the battery is undercharged, so it steps up the output current of the alternator system and thus overcharges the battery (and boils the water/electrolyte off, and eventually kills the battery). The rectifier/regulator rarely --- very rarely --- goes bad.

If the plastic connector shells holding the green/brown set of wires (running to the alternator housing) or the 3 white wires running out from the alternator (and to the regulator within the large 8-cavity connector shell) are hot, or seem to be melting, that's a sure sign of a charging system problem, and usually due to terminal corrosion within those connector shells.

 

I will throw this one out there; if you get to the point of total frustration, send me your carb rack and I will mount it on my motor and do what it takes to work the bugs out if you cover the shipping. No BS or games and you can just pay it forward. This way it gets set up on a known running motor and I will work everything to the book, doesn't mean it will be exact to your motor but it will be close enough to dial in. PM me if you're interested.

 

Ignore this. Sorry