Need to resolve this...

I have a big problem....my xj700 '85 is running high on gas.....you can even smell it...i had to remove the air filter so it can start and run. So I figured that might be a carb problem...you know too much gas coming in and not to much air ... I changed the main jets from #102 to #100 and get worse... do I need to get a set of #95??? I also replaced the diafragms...any advice???

 

Is your bike stock? If so, go back to the stock jets, and a stock paper air filter. Yes, you will have to go through the carbs. When I got my 85 XJ700 it was fouling out plugs and getting about 25 mpg. It was a stock bike but the previous owner had installed a Uni foam filter which lets in a lot more air. I cleaned the carbs--all jets are stock size--, wet set the floats, did a bench sync and then installed the carbs, did a running sync using a two bottle manometer and installed a stock paper filter. The valves had been previously adjusted. I initially set the pilot screws at 2 1/2 and then used a colortune plug to help fine tune the pilots. I did this by closing the pilot screws until I got a lean (white) flame and then opened the pilot until I got a blue flame. Then I installed new plugs and rode the bike and checked the plugs, adjusting the pilot screws (about the width of a dime) as needed until I got a nice brownish plug reading. My pilots are out anywhere from 1 3/4 to 2 1/4. the bike starts and runs well and I get about 42 mpg on the road and almost 40 overall.

 

Sounds like float levels too high or float valve leaking or o-ring on float valve not sealing . Had that happen to my sons zx6 was drowning in fuel until I turn off the fuel and a few minutes later it ran great for another minute then died. A new set of o-rings and presto , it runs fine again

 

I'll check all that Toomanybikes. Tabaka45...I don't know what a color tuning is or how to use it and really doubt I can find it here. I'll go back to jets that were on the bike (a set of #102), but I don't know what to do to make it work with the paper air filter...

 

Float levels. Check your float levels. Like Toomanybikes said.

 

Colortune plug

http://www.ebay.com/itm/Gunson-Colortune-14mm-Kit-colourtune-spark-plug-carb-mixture-/130758004248

Stock paper air filter (Chacal also has them)

http://www.ebay.com/itm/YAMAHA-AIR-...m3a67478f34:m:mGjRWXfyM5b8dW3rCaiLdOQ&vxp=mtr

 

Rod, I know you're remote with limited parts/resources. I'll channel my early farm bike days when all we had was the tools that came with the bike. Sounds like you are running rich. Check to make sure the choke/enrichener is not stuck partly on, this needs to "turn off" completely or you will be rich. Also checking float levels is free if you have a little piece of tubing. Unless something really went wrong/fell apart in the carbs, you probably have a stuck float or three, dirty or bad needle/seat, or the choke is stuck on.

http://www.xj4ever.com/setting fuel levels.pdf

 

jayrodoh...not only far away for a mayor city but all you can find here are mechanics of those chinese little bikes 150 to 250cc...there is a new generation of mechanics that never saw the inside of a '80s big bike...not even talking 4 carbs...so everything in this bike needs to be done by me with homemade stuff, lots of luck, the forum help and pieces of other bikes/cars i can find to match the specs or close so I can work on it...

So back to this problem...this is the latest... I put back the old jets, put back the air paper filter, clean spark plugs...and won't start not even pushing...checked sparkplugs and they are wet with gas and black, that kind of black you can removed with a cloth and the spark shine again. Everyone thinks is the float levels wich I'll check them but How in hell went wrong after 5 years I have this bike?

Just checking out the .pdf you sent I realize I can't get those rulers or the graduated clear tubing, just a tubing, not even mention the replacement parts...I'll read it and see what I can do

 

A piece of tubing with pen marks or a piece of tape on it works. You can kinda eyeball it if you had too, when you put the tube against the side of the carb bowl, put the open end against the bottom of the carb where the bowl mounts (the open end of tube will be level with top of fuel bowl). This will give you an idea if its stuck/set wrong etc. as fuel will come out of the tube.

 

The levels might not be wrong, the float valves (needles and seats) may just be failing. Or some gunk got past your fuel screen/filter and is holding them open.

 

I was just surfing thru and found this thread, I'm having pretty close to the same problem. background is... I'm just about done with a total re-build of the whole '85 XJ 700 (air), Re-done the carbs, all stock jets, cleaned and re-used foam filter that was in bike (never heard anything about a paper filter till now), only change is set of slash cut shorty pipes but conected to the stock 4 into 2 manifold. I am wondering if my header are already starting to color only after several times of start-ups in the garage (20 min. total) and smells rich even though it starts great and idles good and revs real nice. I am woried about it running too rich ? I am asking if the problem could be that I damaged the needles upon install and had to straighten and fine sand them to re-use, how much of my problem could be coming from poor needle seating or incorect taper ( I did do it by hand and eye ) Any help out there for me?

 

@Wagy:

Understood, however, Rod has a unusual case because he doesn't have access to tools and such that we do. Please start your own thread. We will help you there.

Gary H.

 

It is also very possible that the slide needles and/or emulsion tubes are worn where the needles slide down into them. This would not be the first time I've come across this. If the needles are worn, or the holes are worn, then excessive amounts of fuel are going to dump right through the main jets.

Another thing to check, is to make sure that all the jets are in their correct places. Some of them may be able to incorrectly fit in the wrong positions.....but I'd start looking at the emulsion tubes, personally.

Dave

 

First of all thanks to pay attention and your time into my problem...Second, yesterday afternoon after my writing in this forum I decided to try and start the bike one more time and yes it start and after a minutes idle too!! So I took it for a ride...everything went right if I consider that I had the paper filter on this time...the response in the throttle above 3000rpm was good, and lower than 3000rpm the bike jerks a little in the same way he used to do it without the air filter. Resuming I'm happy because now is running with the filter...downside is this jerking at lower rpm that I want to get rid off. A car wizard (mechanic) that heard of my problem came to see the bike and told me that probably the problem is the "advance" of the engine. I don't really know how's the term in Technical English but let's say the bike could be out of tune or point? And he ask me is this bike have a electronic advance or a mechanical advance point...someone knows this? Is the first time someone mention me that as a could be problem...

 

BTW...today in the afternoon I'll take it to a shop to remove the valve cover and hopefully this guy show me how to set the bike on the right point...plus checking all the valves clearence...

 

I believe all xjs utilize the tci (transistor controlled ignition) for electronic advance. This is under the left side cover on mine, I imagine yours would be too.

 

Not likely I'm afraid ignition is fully electronic. Once teh valves are checked/adjusted, I'd take the carbs apart and check o-rings on the float needle seat.

 

a100man, i'll do that even I really don't want to...but need it...

 

Any chance that can go wrong a little? or is just those electronics that totally fails or works fine?

 

I really doubt that something could go wrong that would impact only the advance at low RPM's but not beyond. but I am certainly no expert. You can check some things with the TCI, but I honestly don't believe that it is at fault here. From the XJ4ever site:

There are three main problems that TCI units succumb to after years of reliable service:

1) bad solder joints on some of the internal components (known as "cold solder joints") result in the component pieces coming loose from the circuit board, and thus they can no longer perform their function reliably (or at all).

2) component failure......a blow-up transistor, a burned circuit trace, etc. This situation can develop if you have a short-circuit in your electrical system, or hook up your battery or jumper cables incorrectly, etc. TCI units do not like "big blue sparks" in the electrical system (except at the spark plugs, of course!).

3) another common failure of these units occurs if the TCI is continuously grounding the ignition coil (i.e. its output driver is shorted). You can verify this situation with an ohmmeter with the following tests:

- disconnect the 2-pin plug at the ignition coil and measure from the orange or grey wire to the chassis. You should see very high resistance. This should be pretty close on both the working and non-working channels.

- if you read a few ohms of resistance or less, then the TCI is bad. A shorted driver will also make the ignition coil run very hot and may ruin the coil.

4) dirty external terminal connections.

That having been said, my guess would be that the problem lies in the carbs somewhere. You mentioned getting new diaphragms, when you were doing that, did the vacuum pistons pass the "clunk test"? Also, you mentioned that you changed the main jets. what are your pilots at?

 

A clunk test?... I went back to the old jets already on the bike when I got it. All are #102...even manual says should be #107

 

The clunk test is just making sure that the piston moves freely in the bore without catching at all. If you hold the piston at the top of the bore and let go, it should reach the bottom of the bore quickly and with a clunk. Reading back through this thread, did you ever get to check the float levels? If you don't have the tools available to you, maybe your buddy at the shop does? I think that is the most likely culprit. The valve clearances are a good idea, but if you only had time to do one thing today, I would make sure your floats are set correctly. Have you smelled your oil? Please make sure it doesn't smell like gas, if you are running too rich even with leaner jets, something isn't right.

You also got some good advice earlier, like Drew saidyour float levels might be OK, but the float needle got stuck, or is not closing fully because of dirt or other debris in there. And Hogfiddles mentions the emulsion tube (the one that the needle on the vacuum piston goes into) as a potential source of issues, did you check that?

 

You do NOT have an ignition problem... if your carbs are not fully synched it will cause problems at various low rpm while higher rpm it smooth's out I.E. if it is off wrong amount of fuel delivered to cylinder . If you can ride it for a few miles , pull plugs see what they look like , black sooted up plugs is an indication of this. Or idle mixture screws are not set properly .

 

TheCrazyGnat yes it passed the Clunk Test. We're pretty sure that is some of the valves in the 4th Cil that are the problem. Yesterday I removed the carbs, checked the float needles...they are ok...and once we connect an auxiliary gas tank we started play a little bit with the mixture screws. The screw on the 4th carb was unusual sensitive and still running rich. So tomorrow we are going to open the valves cover to see if there is any valve bothering. The oil is used but the only smell it has it's kind of a smoke...meaning time for a change with filter.

Jetfixer...yeap, the sparkplugs are black within a few miles riding...

 

OK, well, if the oil doesn't smell of gas, your needles are probably OK, I think. I would still think the float height may be off or, as hogfiddles mentioned, there may be an issue with the emulsion tube.

Going further down to more unlikely causes, maybe the large spring under the carb hat is weaker than the rest? Is there any chance that the jets in carb 4 were drilled out a little bit or otherwise opened? There are also two different kind of idle mixture screws, one with a finer thread than the other, is it possible that the 4th carb has the less fine thread, making adjustments more dramatic on that one?

It is never a bad idea to check the valve clearances, etc. if it hasn't been done before.

 

Valve clearences was checked a couple weeks ago and exhaust in the 4th cil was pretty close, not sure if the fixing was done right that's why this time I'm present in each step. The jets weren't drill or no sign of it at least. What I meant by playing with the mixture screws is we were playing with the ones on to top of the carbs beside the hat. To add one more thing that might be relevant and didn't mention before is that when I tried to push it to get her start got it 2nd gear and it was heavy as hell just to push it...after a few tries got lighter to push...I don't know if really matter but it feels like the engine was stuck...which also point me to valves...I guess

 

Valve clearences was checked a couple weeks ago and exhaust in the 4th cil was pretty close, not sure if the fixing was done right that's why this time I'm present in each step. The jets weren't drill or no sign of it at least. What I meant by playing with the mixture screws is we were playing with the ones on to top of the carbs beside the hat. To add one more thing that might be relevant and didn't mention before is that when I tried to push it to get her start got it 2nd gear and it was heavy as hell just to push it...after a few tries got lighter to push...I don't know if really matter but it feels like the engine was stuck...which also point me to valves...I guess

 

Ok...guys...The mystery is resolved...even seems weird but the TCI is failing. Yesterday afternoon opened the valve cover, check every valve clearences, everyone except one were within specs, which putted back within specs. So I decided to check the TCI, pulled out, unplugged, clean it, plugged again and started the bike...and I have to tell you that bike was another bike... Took it for a ride and indeed I was riding another bike, very smooth from 0 to 2500rpm were before was rough as hell. The thing was bothering me from beginning is that is carbs were failing can't be all of them at once it's the same with valves...so why I was getting all the sparksplugs black?... So I'll move to the thread of the guy that said had problems with the TCI... and read the links on that...Thanks everyone of you guys...

 

You can't know this unless the TCI is tested.

Sounds like the TCI is ok. If you don't follow the step by step format for resurrecting your bike you'll be chasing problems for a long time.

Gary H.

 

After cleaning the contacts it was ok... really don't know inside I'll have someone to look at it... But I follow every steps as far as carbs and valves. Thing seems little weird since all valves cannot fail at the same time, same with carbs...all sparkplugs getting wet with gas...can't be all the needles stuck at the same time.
So far all valves were within specs, except one...there is no more to check there, right?...and Carbs were clean, levels adjusted, needles cleaned, diaphragms changed, clunk tested, jets cleaned, mixture screws adjusted, and forget to mention something I did on that for sure... Point is, cannot fail everything all together right? that's why start looking at the tci... Can't think of every thing else that can mess with everything and make it look like a carb problem

 

Right.

Right.

Got a multimeter? Electrical issues on these bikes have to be resolved by process of elimination through testing.

Gary H.

 

You are right...that's why I decided to check the TCI is the only one electrical component that can fail and make all the spark plugs black within 1 mile ride or make them wet with gas by sending a out-of-time signal to fire the sparks plugs...since I'm studying automotive electricity I'll take the TCI to my teacher which is also a electronic teacher and see If he can test it...right know I have a problem with started switch...one of the pins broke...tomorrow I'll buy one.

 

Open it. The wiring may not be soldered + dirt/corrosion at the contact. You can rebuild it.

Gary H.

 

It seems it was open in the past. I'll open it on monday when I get the starter which caused me a lot of trouble making me think its a battery problem...