XJ650 Seca 1980 Not working right part 2

Hello again
A while ago I had a problem with my 1980 xj650 seca (carburetor problems).
With your help I was able to dismantle and clean the carburetors and the problem seemed to have been solved ... the bike started to work very well.
However, it started with ignition problems (not all cylinders work). I think it could be a bad battery, but I'm not sure. When the bike is already working, could a battery cause this problem?
Thank you all

 

No, the battery just supplies voltage to spin the starter. If you have have cylinders not firing, either you have a coil/wire/cap/plug;/etc.... issue, or you have a carb/fuel issue

 

Hello.
Are you sure the battery only does that !?
I have a 1980 xj650 seca that comes with a Blackbox Type TID14-02 4H7-10 and I think it gets the battery current.
But thanks anyway for your attention.

 

Yup.
The black box is your TCI

 

Low battery voltage could cause an ignition problem, but not likely if the battery was strong enough to start the bike to get it running. Now if the charging system is not working and you went out for a ride after a while the battery would drain and you might develop ignition problems before the bike just quit running.

It's a very simple check with a DMM to check the battery / charging system. First, start with a fully charged battery and connect the DMM across the battery and measure the voltage with the bike running. It should go to 14.5 +/- .3 volts when the engine is revved to approximately 2500 rpm.

To check the battery start with a fully charged battery, which should measure 12.6 volts after a full charge and sitting overnight. Next, connect the DMM across the battery and while starting the bike observe the voltage - it should stay above 10 volts with the starter engaged.

^^^ This is the most likely issue. Do you have a manual to check the ignition system with a DMM?

 

Thanks for the help ... It was a bad battery and spark problem( wrong plugs). The bike now starts very well but I noticed that cylinder 1 heats up much faster than cylinder 4. After 2 minutes, cylinder 1 is very hot while cylinder 4 is at half the temperature. This is normal? Does anyone have any idea what the problem will be?
Thanks

 

I guess we totally didn’t understand your question..... sorry.
I thought you meant you were have trouble while it was running . I didn’t realize you meant ‘ my bike won’t start ‘

 

My fault.
I had a problem with the carburetors, but it's also solved.
Thanks

 

Yes, the problem will be either :- not enough air, not enough fuel, not enough spark, not enough compression (unlikely), not enough or no valve clearances, or maybe a combination of more than one of these.
The point of my answer is you have to check each of these possibilities on at a time, and if you don't know how, you need to learn - it will be one of the best things you've ever achieved.

 

Thank you for your help.
I will start by seeing all of this.
But what is your opinion? Is it cylinder 123 that is heating up very quickly (after 1 minute) or cylinder 4 that is heating up a little?

 

Cylinder 4 is your problem.

 

Hello.
I have my xj650 working at 75%.
Cylinder number 4 does not receive fuel.
The carburetors were cleaned and the entire carburetor circuit number 4 was overhauled again. Does anyone have any idea what could be causing the fuel shortage?
Thanks

 

If bike is on side stand and fuel flow from tank is poor #4 will get less fuel than needed. Check the vent in the gas cap and the tap itself.

 

Hello.
thanks for the help ... but after diagnosing the problem, i removed the tank from the bike, and i am using an auxiliary tank. so the problem is not with the tank ... and when I tighten or loosen the mixing screw I don't have any change in the engine ... I don't have any ignition in the cylinder.

 

Check the spark plug cap to high tension lead joint on number four cylinder. Cap unscrews make sure you have clean bare wire which can contact the screw type thread in the cap. If you don't have cut the lead back slightly to expose the wire and then screw the cap back onto the lead and try starting the engine.

You could also remove the cap on the intake stub of number four carburettor where your vaccum gauge would fit onto. Spray a little engine start inside, fit the cap and try and start the engine to make double sure it is not lack of fuel in carburettor number four.

 

I have a good spark on the cylinder ... the spark caps are new (NGK).
I bet on the lack of fuel, but I don’t know where? I've disassembled carburetor number 4 many times and I can't find any blockage. Could the valves cause the cylinder not to ignite?

 

I misunderstood. You have a spark but no fuel air mixture being ignited. Valve clearances I would check next it is best to make sure they are all within specifications. A tight inlet valve clearance would make the valve open too early which would not help with combustion of the fuel air mixture.

 

Is there fuel in the bowl?

 

Is there fuel actually getting into that carb? The fuel feeds can become blocked. With the aux tank on, open the float bowl drain screw on #4 to be sure that fuel is entering.

 

Thanks for the help ... I will order the gasket and then I will see the valves.

Yes, there is fuel in the carburator

 

I tested the fuel passages with compressed air and they all seem to be clear.
My biggest doubt is to know why I don't have any kind of alteration in the operation of the engine when I remove the spark cap or close the entire mixture screw.

 

Sorry if I missed anything but can you check compression? I’d be interested in the reading and valve clearance.

 

I'll chuck in my two penneth worth.
You say you've blown through the passageways with compressed air, but what about the passageway for the pilot jet, that's the one down at the bottom of the tunnel at the side of the main jet.
That passageway can get a partial blockage and i had this problem on a set of 34mm Mikuni's fitted to a XJ1100. I was positive it was totally clear.

 

And from me - you have to squirt carb cleaner through these, and check you get the same "squirt" out of all four of them - kind of an easy comparison check if you like?
Blowing them doesn't tell you anything or at least everything.

 

With you there mate, i didn't want to say but i put through nearly two tins of aerosol to clear it.

 

Thank you all.
I will try to check everything again on carburetor 4. And as soon as I have the tool to test the compression I will put the results here.
Thank you again

 

With the bike running and the carb to air box boots off, see if you can block off the back of the carb with your hand. This will more or less force gas to be sucked up into the carb. It might, just might unblock anything that could be holding back the fuel. While doing this test and all fuel related testing, make sure you have the bike on the center stand. You said you were using a AUX gas source, but if the bike is still leaning on the side stand the carbs will not be flat and level. Having it placed on the center stand will help trouble shoot the carbs (imho).

You have checked the #4 spark plug by pulling it out of the cylinder and make sure it is sparking as the bike is running? The bike will run on the other three cylinder as you do this.

Keep us posted on how you are doing and what steps you are taking. Carbs are no joke, when they are out, do a really good job on them the first time. I have pulled carbs as many as six times before I got the right. Now I really am careful and take my time to do them right. Using thin wire, carb cleaner ( I use chem tool B12) and compressed air.

 

Lots of good suggestion above - one other possibility is a large vacuum leak from the intake manifold boot because of large cracks or a defective gasket.

 

My XJ would not start, I thought I had cleaned the carburettors properly but at the time I didn't know about the float bowl jets. Once cleaned the bike started. It was on this site I found out about those hidden jets.

 

Well,when I asked if there is fuel in the bowl, and you said there is fuel in the bowl, then there is not a fuel shortage. You need to determine if fuel is getting into the cylinder. Then you need to find out if you are getting spark.

 

This is what I already checked:
I have a good spark in all cylinders;
Fuel reaches all carburetors;
The jets are all open;
When I close the air intake of carburetor 4 by hand, fuel comes out;
The mixing screw was removed and the orifice cleaned;

What I haven't done yet:

Compression test;
And checking the valves

Thank you all

 

Put a direct line of current to the starter so you can spin the engine with no spark. Then Remove spark plug number four To see if the spark plug is wet. If it is wet, you have fuel to the cylinder. If it is not wet, you have no fuel getting into the cylinder

 

I have a similar problem with mine. Cylinder 1 just never fired no matter where the mixture screw was. I think it turned out to be a clogged jet (even after poking wire through all of them to make sure they were clean). There are (I believe) 4 of them and one of them was clogged. I have the carb sitting in my ultrasonic cleaner, and I am making sure all the jets are clean this time. If it still doesn't work, you've got more troubleshooting ahead. I would make sure the electrical system is still in spec and no parts have too much or too little resistance. Then check the valves before compression. Bad clearances can lead to compression tests with false values. Valves will change a lot on the bike, and it feels, pulls, and sounds 100x better with the clearances fixed.

 

NOT A GOOD IDEA!!!

while many of us DO that, it’s very dangerous. If the gas is getting into the cylinder, you are now blowing it (atomized) out of the spark plug hole—- hope the spark from the plug you’re checking doesn’t ignite it!!!!! You won’t have enough time to say “UH-[insert big explosion here]-OH”.

 

Fair enough...sorry for giving advice that could be potentially dangerous. In my defense I was hoping that some common sense would prevail.

 

No prob...... like I said — a lot of us DO do it that way and, yes, common sense SHOULD prevail. But sometimes the desire to get something working, coupled with the frustration of it NOT working can lead to impulsive action. That can blind some common sense at times.

 

Hello everyone.
I come to make an update.
The problem of cylinder 4 seems to be solved (I cleaned the carburetor again) however, although cylinder 4 already works, it seems to be only 80%.
When I turn off the motorcycle, some smoke continues to escape from the exhaust on the
right
side of the motorcycle. Does this mean a possible problem with the exhaust valve on cylinder 4?
Thanks

 

Sounds like either it’s loading up with fuel or excessive oil in the exhaust pipe.

1. Did you do a compression test yet?
2. Did you check valve clearances yet?
3. Did you sync the carbs yet?

 

No,No and No
I don't have the pressure test yet.
Thanks

 

Can someone help me on the wiring please