I'm just about at my wits end with this thing

Have you entertained the idea of a possible electrical problem. There is a lot of old crap on these bikes that have the potential to cause some rather baffling headaches.

It sounds like you have the "fuel" aspect covered, so make sure that you don't have any air leaks (the source of most of my problems). As long as your carbs are correctly bench synced, I would move on to spark and voltage.

 

I've got spark on all four. I'm replacing the plugs with the 8es vs the 7es tomorrow. the ones in there are not all that pretty. I thought about swapping cdi's

 

I switched to champion plugs this year, seems like the NGK's only last 1 year. New plugs always seem to bring new life in the spring (for me anyway)

The cdi is worth looking into, also the fuse block.

How is the battery? What about plug wires and caps?

 

Whoa, ....

25-Percent different.
No.

If the Gas contains 10~12 Percent Ethanol ... allowed by Law.
You're talking ... maybe 6 or 7 Percent.
Not 25 Percent.

 

I've heard a lot of talk about ethynol's poor performance issues with newer cars, but how does it effect our older bikes? It's kinda like an octane boost isn't it. And who know what your really getting at the pump these days.

 

Once the Season gets to where the Sun is out and the roads are dry; I spend as much time on the Bike as I can get.

I don't fool around with New England Summer Regular.
I go the extra Dime and get High Test.

 

Any additional thoughts on what might be the culprit here? I'm beginning to wonder if I have bad gas in the bike (I do regurally as well :lol: ). I'll swap plugs consult the local guru and try different gas. I'm starting to really hate airheads. I've never had this much issue with x's. I've had 2 airheads and they have been total beasts.

 

Hey MC, when you cleaned the carbs did you take the mixture screws out and inspect to see if there's any of the same crap in that circut? I did some carb work this weekend on some Hitachi's. Those little mixture screws make a big difference.
Make sure the Oring at the bottom comes out ,you might have to pick it out with a dental pick. Put it back in this order-screw,spring,steel washer,oring. Turn them all out 2.5 turns.
Don't get discouraged. I do lots and lots carb cleans at work. Which carbs do I have to pull twice...............mine.

 

don't get angry - sounds to my like you fixed one problem and uncovered another problem. it was running too rich, right? with wet plugs and gas in the manifold. now that you fixed that, you've discovered that the carbs really wanted to run lean, but the floats wouldn't let them.

#1 not firing: try swapping the spark plug wire with #4 - that will tell you if it's carbs or electrical.

i had an idea you might want to try - the way the pilot circuit is routed through the carb - it's hard to get the compressed air to go where you want it. i.e. if you blast air into the pilot fuel jet, most of it blows out the pilot air jet and it's hard to block the air jet off to force the air through the port(s) in the carb throat - the tiny tiny holes that you really want to make sure are clean. if you have a spare jet that you can clog up with solder or something - install that as a temporary air jet and then shoot air into the pilot fuel jet - that will force all the compressed air out the fuel port and really blast it clean. i'll be doing this next time i have my carbs off (why do i always get an idea after i re-install??)

 

#1 not firing: try swapping the spark plug wire with #4 - that will tell you if it's carbs or electrical.

I totally forgot about this, thank you. I'll give that a go. Weird thing is that the bike ran on all four rich as can be. Heck, it might just be that the plugs are all fouled even after a cleaning.

The mixture screws were completely taken out in order, and replaced in order. I've had that issue before as well, but nothing was in that circuit. I pulled everything off the carbs without breaking the rack. Guys, you should see these things, they are beautiful. I'm getting a compression guage today with new plugs and I will run a test across the board. I am also going to see if there is a manifold leak somewhere, but I dont' believe there to be one. Desinger Mike is going to be sending me a rack to try off an 86 xj700n and we'll see if it is something there. I'm thinking it is something else other than the carbs due to the fact that everything is correct to my knowledge.

here is what I have on my to do list for this bike

new plugs and plug caps (snipping the end of each wire a bit to expose new wire)
-see if it will run
--if not, swap wire 1 and 4 so see if the problem follows
check for air leak if able
do a compression test

battery is good, mixture is at 2.5

seat and needle rebuild kits coming by the end of the week I hope. Hopefully the new plugs make a difference...

 

compression is at 120, 130, 130, 120. New plugs, new spark cap. New needles and seats on order. Carbs are off. Float levels (funny enough) are at 17mm on 2-4...1, which isn't firing is at 16. Bike runs on all four when ether is injected, then dies as soon as it is gone. hmmm 1+1 = ? anyone? I'm hoping anyway

I just swapped 1& 4 floats, and the float height changed. what in the world? I believe that the needles are toast. you can see a ring around the rubber portion of it where it sat in the seat for some time. I'm going to wait until I have the new needles and seats to go any further

 

644, don't part out the bike! You're so close to getting it going and when you do, you will be a bona fide XJ expert!

I'm really interested in following this thread while slowly gaining an understanding of the intricacies of our bikes (and specifically the carbs). The troubleshooting here is great.

I'm not incredibly technically experienced, so I suppose the only advice I can offer is to actively avoid getting tunnel vision. Don't focus on a single part, that may or may not be the cause of the issue, for too long.

In computer programming, it's common for people to spend way too long on a solution that is less than ideal simply because they didn't take that step back, that 30-minute break to let their brain reorganize and rethink the problem.

More of general piece of advice to anybody solving a any problem, really.

And that is my $0.02. Good luck!

 

shnuffy, this is the first bike to give me this much trouble, and I've owned I think 8 or nine xj700/700x's. I'll offer up one thing, don't overlook a single piece on these suckers. This bike has sat for 7 years and I saw things on it I have never seen before. I'm not parting it out, I was just very frustrated with it. I have every confidence it will fire right over when I get the new parts and on the bike.

 

Good news!

I just started working on mine yesterday after 7 years of (garaged) sitting. Nothing could possibly go wrong...

 

my order for new needles and seats went out today, or late yesterday from NY, that should mean they are hear by Saturday

 

I polished the vacuum slide bores while waiting for my parts. I also put the new needles and seats in yesterday. I reset the float heights 2x to get them right. Bike back talked me a bit, but did start after a few mins.

I've got 0 power from idle to about 4k though, but I believe it is due to needing a sync. I'm also running a bit rich, which I'll TS down today. I took her out for a ride and found that the lack of power was in every gear which tells me carbs.

I went for a 35 mi ride and was very comfortable on her. I love those pirellis and for 200 installed, I can't complain on the price.

A word on the rebuild kits...the needle 'tangs' for lack of a better word, need to be installed and they are a bit tricky to get into the correct position so they'll stay on, but otherwise, the price was right....
Oh, and she MOVES!

 

Did you set the float height with gas and the "clear tube method" or stop after the dry adjustment?

Did you bench sync while you had the rack off?

You're finally learning what everyone learns about these bikes eventually: You have to go through EVERYTHING, front to back and top to bottom, to reverse the neglect and deterioration.

FAILURE to do that; the neglect of one small thing, no matter how seemingly inconsequential, can bite you and probably will.

After fixing all the bites, you end up having done it anyway. I prefer to be the one in charge.