Won't fire after carb rebuild

It's been a fun several months as I've picked away at recommissioning my '83 XJ650K. A lack of, well, any free time has put me a couple months behind schedule where I wanted to be but I told myself from the get-go that I was going to take my time and do it right so that's okay. Thanks to many on this forum for answering others' questions (I've been a lurking, searching, bookmarking fiend), and Chacal for supplying me with just about every part I could ever need, I've come quite a ways on a project that in many ways has been an entirely new experience.

But now I'm at an impasse, and I'm really hoping it's just some dumb rookie mistake I'm making that is causing my bike to not fire up. Here's a list of what I've done so far (or at least what's relevant here): completely dissembled the carbs, replaced all seals and gaskets, scrubbed them down and cleared out every jet and passage (enrichment circuit jets included), reassembled assuring they're parallel/perpendicular to each other, performed clunk test on all 4 carbs, bench syned, wet set the floats (the most any of them vary from the desired 3 mm from top of bowl/gasket surface is ~0.25mm), put them back on the bike ensuring all boots are snug, reconnected the enrichment circuit and throttle cables with them functioning within their desired range of motion, replaced the spark plugs and have checked that the electrode gap is within spec, checked valve clearances and replaced shims as necessary so that all valves clearances are now within spec, and have a brand new battery that is fully charged on the bike.

I have spark across all four spark plugs, and an auxiliary fuel tank hooked up to the fuel rail inlet with fresh gas (87 w/ Techron, no 100% gas available in my area). The float wet setting procedure was smooth as silk so I have no doubts that fuel is flowing. I have no reason to believe that there is any blockage in the air intake. So as far as I can tell, I have fire, fuel, and air... and yet when I turn the key and hold the start button, no matter where I have the "choke" lever, how I play with the throttle, or how long I let the starter crank, the engine just will not fire.

I have all four pilot screws out from bottom 2.25 turns as from what I've read that's generally where they want to be. And yes, their o-rings and washers were replaced.

Can anyone think of something I may have missed? The kickstand is not down, the transmission is in neutral, and the engine kill switch is on run.

The only anomalies that I can think of are the following (whether they would affect the starting procedure I do not know):

- The oil level indicator is currently showing at about half way up the window (not to the top with a small bubble as it should be, I intend to do an oil change once I get the engine running again and can warm up the oil before draining it).
- The headlight does NOT come on when the key is in the On position. It did pop on at one point while I was trying to start it, but after messing with a few things it didn't come on again. Even when it came on the engine still wouldn't fire anyway, so I'm assuming there isn't a headlight-isn't-working-don't-let-it-run safeguard. Everything else electrical appears to work as it should consistantly.
- There is a bolt that I believe helps mounts the air box to the frame, the that is below and toward the front of the bike in relation to the TDI unit, and also acts acts as a grounding spot. This bolt has broken off inside the airbox or whatever it is it screws into, and at the moment can not correctly hold the grounding strap securely to the frame.
- I did rebuild the fuse box with one of the kits Chacal provides, and it's all solid as a rock, as far as I can tell.
- I have NOT run a compression test yet. I did buy a compression test gauge however have not used it yet as I believe you are suppose to allow the engine to warm up before doing so. Knowing the bike ran before it came into my possession (or so I'm led to believe), I can't imagine the compression would be so bad that the engine wouldn't even fire.
- There is a little more slack in the clutch control lever than there should be, however I am still able to shift from first to neutral without the bike running, and with the transmission in neutral, it's my understanding the engine should be able to start regardless of the clutch lever being depressed or not. I intend to lube the control cables and then do final adjustments before putting the bike on the road.

That's all I can think of now; thank you to those that bothered to read everything. Any suggestions would be greatly appreciated!

Furman

 

Did you try attaching that ground cable somehow?

 

How about enrichment lever "choke" to off and a little starter fluid? If you get a "cough" then advance the lever a bit at a time.
Definitely recharge the battery every bunch of starts.

 

Not yet but I will figure out some way to do so just to eliminate that variable if anything.

I have the battery back on the tender now, I didn't do so before the first round of trying to get it starter, so maybe that will help. The starter didn't seem to lack strength, but we'll see...

I'll try some starter fluid as you suggested, thanks for the tip!

 

Starter fluid would be good for diagnosis. Have you tried a push start to rule out starter problems? I have a minor float needle problem, so if I leave the petcock (I have a manual aftermarket one) "on", mine won't start--but it will push start. Put it in third, hold in the clutch, run with it, release clutch, keep running, once it starts puttering pull in the clutch and keep pulling back on throttle, keep pushing to help it out.

Small chance, but possible that the kill switch has gone bad, or one of your safety circuits is stuck activated.

Try opening up the screws more, say 3 turns.

Unscrew the bowl drain screws with the carbs on bike just to make sure you have fuel in all 4?

More expanded troubleshooting checklist: Air/fuel, timing/spark, compression.

Air and fuel have to be in the right ratio to 'count' as satisfied, and we can't know for sure (many have *very* thoroughly cleaned their carbs only to find out that they weren't actually clear in the smallest passages, it happens) until the bike is running that the carbs are giving the right ratio, so that's one.

Was the spark strong? It should be easily and clearly visible in daylight.

Timing is basically a non-issue on these bikes if you don't screw with the chain, from what I understand. TCI is the other factor for this and spark.

Is your air filter clean and clear?

Are your boots all on correctly and firmly fitted?

 

Does the bike even fire once (for even a split second)? What's the compression like?

 

The engine needs several conditions to start and run.
Fuel
Compression
Ignition / timing

Pull plugs and unhook TCI check compression dry and then add oil to each cylinder and note change in compression
Plug TCI back in & Install plugs and turn over with fully charged battery. Does it spin over freely or does it just barely turn over?
Spray start fluid into air box and try to get it to fire.
Please report findings

MN

 

Boots are all on correctly and firmly fitted, and air filter is clean and clear; I'll double check though. And I don't think the kill switch is bad, when I put it in either off position the starter button doesn't turn the starter motor on, but when in the on position it does.

Spark seemed strong, I was inside the back room of a barn with windows, plenty of naturally light on a sunny day, and I saw easily visible white arcs across all plugs.

I think I'm going to drain the bowls and try to start from scratch, but I am sure all 4 carbs are getting fuel as when I first got the carb rack secured in place and got ready to fire it up I forgot I hadn't tightened 3 of 4 drain screws and when I open the valve on the gas tank, well, I think you know what happened next! hah

Unfortunately I don't really have the room to trying a running push start, but I will give the starter fluid a go or two.

And I am in no way counting out the possibility that I didn't get every passage in the carbs "zestfully" clean. I'm going to try to rule out as many other possibilities that I can before I go through the process of removing them and getting at their insides again. Although I will say, the process no longer intimidates me like it did the first time I pulled them and started dissembling!

Unfortunately I won't have any time tomorrow for bike work, so this will all have to wait for Sunday. I'll report back then, and thanks again!

 

The very first time I turned the key and pressed the start button if fired for a split second, and then just turned and turned and turned and turned. Some time later after fiddling with a few things, it did it again, but this time only flirted with firing for a split second.

I'll be checking compression on Sunday, at this point it's unknown.

 

I'll give all this a shot on Sunday. How much oil do I drop in each cylinder, a teaspoon or tablespoon? I believe I've read that elsewhere before.

When I was attempting to start today it was turning over freely, or at least I assume so, as the started motor was running and sounded just as it was when I had the bike running before I pulled the carb rack. Maybe it isn't engaging the engine as it should? I'm going to assume this isn't the case for as I mentioned in my previous post the very first time I tried to start it it did show a sign of life, albeit brief.

I think I'm going to investigate the starter, that's one of the few things on the bike that I have so far not touched.

 

Teaspoon of oil in ea cylinder

 

I had the same problem of good spark, no combustion on # 1. I was using a colortune plug and could actually see that there was no combustion. Finally at 4 1/2 turns open, I got ignition and it ran well. Try opening the pilot screws further.

Since my other carbs seemed ok, I have taken the carbs off again and recleaned them, especially # 1, and probed every passage, flooded carb cleaner, and finished with compressed air. hope # 1 works better when I reinstall.

 

Make absolutely sure that battery is ok. Ie load test. If any doubt hook the bike up to a robust source ie car battery and report back please...

 

Im in a similar boat as you.

When i got my XJ550 a month or so ago, the carbs had fuel sitting in it for months. It was stinky. I charged the battery and tried to start and it would only turn over. Long story short and quite a few carb pulls and half-assed cleaning attempts, i was finally at a point where i could get the bike to start on first try every time, but it would only run for a total of 5 mins or so and would refuse to start again. I suspected float needles were getting stuck.

I pulled the carbs and cleaned everything again, this time pulling emulsion tubes, dry and wet set floats, replaced pilot fuel jets, pilot o-rings, needles and needle seats. I replaced the carbs on the bike and it completely refused to start without the use of starting fluid and when it did run, it ran terrible with high idle, etc...

Someone suggested to replace my throttle seals. I have them on the way now. Since i was breaking the rack apart, i went and bought some carb/parts dip and have let them suckers soak. I have been impressed with the results. I have used extra carb cleaner and compressor to make sure ALL jets, circuits, orfices, etc have been cleaned and flowing. Ive also just changed my oil/filter and spark plugs today.

Anyways, hopefully ill get my throttle seals tomorrow and ill be able to re-assemble my carbs, bench sync and try them back on the bike. Im really hoping this extra effort will really help

I know ive rambled on about my dilemmas, but sounded similar to yours..

This place has been a great resource and i have learned so much.
Im curious to know the outcome of your efforts. Putting the effort in, and it still isnt running, its easy to get discouraged.

Good luck to you

 

2.25 Turns Out on Pilot Screws isn't enough to run the Bike.

2.5 was the Factory Preset ... (Lean)
2.75 was the 500 mile reset ... (still lean).

+3.00 is the Colortune era setting.

Open the #-4 drain and ck to see if the Bowls are filing.
Do a Starting Fluid "Pop" Test.

See if she'll fire after given a gulp of Starting Fluid.
Yes.
Fuel delivery problem.
No.
Ignition related problem.

Get-a-hold of a ColorTune Plug.
Colortune the Idle.
Fine-tune from there.

 

I couldn't help but give it another shot real quick before heading in to work this morning. I adjusted the pilot screws out a half a turn each, putting them at about 3 full turns out from bottom. The battery charger was showing a full charge, so I hooked it back up to the bike, opened up the fuel tank valve and the enrichment circuit, turned the key and hit the start button... and it fired up immediately!

It revved high, settled in at 4k with no throttle, I backed off the choke and it started to calm down but then slowly wound up as it continued to warm up. I'm pumped to tune tomorrow, and I'll still run a compression test and probably pull the starter for a possible cleaning. I almost wish I didn't have a music festival to go today, hah!

 

Sounds like you're ready for your vac sync (with YICS blocked.)

 

Yeah buddy, I have my YICS tool, CarbTune and Colortune at the ready. After a brake fluid bleed (oye!) and oil change I should be good to go.

And for those who would warn: rear shoes have replaced and the entire front brake system has been rebuilt with stainless steel lines.

 

How's this all coming along....?

 

So far, so good. I wound up not having much time to work on it Sunday. I did fire it up again, though, and let it run for a few minutes. It warned up enough that it was running with no choke, but was still taching high (somewhere around 3k). I started to adjust the idle speed stopper out to slow it down but once I adjusted it the engine started to slowly climb in speed. I didn't do too much beyond that.

In my spare time this week I'll be doing some odds and ends: brake bleeding, control cable libe, checking torque on various fasteners. This Sunday will be carb day, I have a buddy who is more experienced in these things who is at the same stage of an '82 Goldwing rebuild, and were going to team up and tune them then.

Thanks again for all the insight everyone, I'll definitely update this thread as I get closer to finishing it!

 

Edit: double post, see below

 

Edit: please forgive the typos, I typed all this on my phone on my lunch hour...

Sunday wound being a wash, the bike was being a bit of a brat and wouldn't start half the time, and when it would run it was taching high still. We Pulled the starter and regreased the internals, cleaned the brushes, etc. as we were concerned because every once and a while while cranking th starter would a pretty nasty grinding noise. Put it back on and it works fine, but still makes a periodic grinding sound, I'll have to record it and ask for opinions.

My friend rode over on his 82 XS850 and we vac synced it with my CarbTune. I must say, the layout differences between his bike and mine make me really glad I bought an XJ! At least I got some experience in synching. We called it a mitt and I once again put the battery on the tender, and backed off on the idle adjustment screw because I had more room to work with letting it out than I thought. My friend also showed me how to use the idle adjuster on the throttle cable up on the handlebar.

Once again, it fired up immediately the next morning, and this time due to the adjustments I had blindly made the day before it idled at a much calmer 2500 to start, and as it warm-up and engine speed increased I was able to coax it down to a more acceptable idle around 1400. Unfortunately I had to leave for work so I wasn't able to do much beyond that, but I was pretty pumped about it all day!

Left work and went on-call at my part-time evening gig so I could get back got the bike, sure enough had it idling at 1100 in no time. So I three in my YICS tool after cleaning the 4 small passages in the YICS channel and hooked up the CarbTune. The bench synch did wonders, they were all relatively close, and after some tweaking I got them all pretty darn close to even.

Next came the ColorTune, which I used to check all 4 cylinders, but I didn't tweak anything, they all looked blue to me and the bike was running great so I didn't want to push my luck. At this point I was considering test ride...

However I noticed a few things that kept me from doing so. One being that from time to time if I made an adjustment for the idle adjuster on the throttle cable, or blipped the throttle, the engine would fire up more than it should have and then hang there, slowly climbing its way down to where it was originally. I'm thinking the throttle cable could use some lubrication, and I'll pull the throttle grip and check that everything involved is as it should, greased, etc.

Even more concerning: with the engine at idle around 1100 I depressed the clutch cable and put it in 1st gear (on center stand, rear wheel up) and even with the clutch lever in to the grip the rear wheel was spinning, and not just a slow spin, but as if it was in gear. I left out the clutch lever and the rear wheel's speed didn't change, so I'm thinking my clutch cable needs so major adjustment!

I removed both throttle grip and clutch lever over the course of my recommissioning, so I'm sure I just didn't put hem on quite right (or so I hope).

So that's here I am now. I won't be able to work on it tonight but tomorrow evening is promising. If I fix those cable concerns I'll probably get for ale it for my first ride (albeit short) so as to warm up the final drive fear oil for a drain and replacement, and then an oil change and I should be good to go!

Also, does anyone know where I can find a fitting for an air pumped that will fit under the handlebars so as to top off the air pressure in the front forks?

 

Re: Your vacuum sync: If the bike wasn't FULLY warmed up (20+ mile ride) beforehand, you may not have gotten as quite an accurate sync as you thought. This would explain the "hanging idle" once it IS warmed up.

Float levels accurately wet-set?

You may also need to "tweak" the mixtures, then re-sync. These things have to be pretty much "spot on" to return to idle as quickly as they rev up.

 

Floats were wet-set and fuel levels are right where they should be.

Make sense to me, I'll definitely continue to tweak once I'm able to take it out for a good warm-up run. The only thing stopping me now is the clutch adjustment, a process I seem to be failing at.

I had it running again last, started right up and very quickly settled in to a nice idle around 1200 or so, maybe a bit higher than desired by the owners manial's standards but right now I'm contributing that the fact that I may be running a tad lean right now. When I take the idle to around 1050 it feels like it's about to bog down and die.

Anyways, clutch issue: with the engine running, if I pull the clutch lever in and shift into first, the rear tire begins to spin, and not just lazily spinning, but really going for, so the clutch is engaged regardless. However, if I apply the rear brake, the rear wheel stops without much of a fight, and engine continues to run as if it's in neutral. I don't recall if I tried this last night with the clutch lever out (clutch supposedly fully engaged), because if I did and the engine didn't die, I'd think I'd have a serious issue because in that case the engine should stall.

I tried adjusting the cable length at the clutch cover and at the lever in both directions with minimal effect. Also, I've now lubed the cable twice and still if I apply the clutch lever fully, and let it out slow, it typically sticks and stays near the grip. I have to let the clutch lever out rapidly in order for it to spring back. While I admit to inexperience and could be doing it wrong, I can't imagine cable adjustment is that complicated and fear that there may be something going on with the clutch itself that's causing this.

Thoughts?

 

Your clutch issue sounds like a cable with some broken strands in the inner cable somewhere, hanging it up. I'd start with a new cable.

 

Sounds like a plan, I'll give that a shot.