xj 1100 running problem

Hi to all forum viewers.
I am looking for hep to get my '83 xj 1100 running properly. I have so far replaced the plugs,coils,ignitor box,air box-damaged when purchased,exhaust gaskets-all.
I have it running but it seems to be not firing properly on cylinders 1 and 2. no load operation is good and response is there. I took it for a ride last night and it bogged out at highway speed and in top 2 gears. I am trying to figure out if it is in the pickup coil or the carbs. The synchro is good and air screws are all set at 3 turns. The other option I am thinking of is the boost sensor not working properly.
Any help to get this figured out would be greatly appreciated.
Trying to get it fixed for Port Dover on Friday.

 

have you cleaned out the carbs and sync'ed them fully? what about mixture screws? did you bench sync and fine tune?

 

I have had them apart and inspected them. No debris found in carbs considering the years of sitting before I got it. I haven't touched the synch screws,visually they both move at the same time. It had #1 slide diaphragm pulled apart when inspected. It is back together and all assembled. I may need to do the in depth carb cleaning and maybe replace the needles and adjust float height. I just don't want to get into it in that depth right now,but I may have to. Could the boost sensor be a cause?

 

I would say that the most likely cause is that your carbs have been sitting and need a good complete cleaning, bench synching, and tuning. also you will need to adjust float levels and mixture screws. you may also have to fool with the idle adjustment screw.

 

I had it running on all cylinders yesterday and had it idling at 1100 rpm instead of the previous 1600 rpm that was needed. I am a diesel mecha nic trying to remember how to get a carburetor sytem working properly!

 

welcome,

testing the boost sensor is pretty easy with a voltmeter. according to the manual, it should read about 2 - 2.4 volts at atmospheric pressure (no vacuum). apply vacuum and the voltage should go down (1.6 - 2 volts at 200 mm Hg). the manual indicates you should jumper the battery to the sensor but if you turn the key on the bike and stick the probes in the connector you should be able to get the same readings (make sure the battery is fully charged). if the readings are incorrect, check the vacuum hose, if it's hard or cracked, replace it and test again.

however i don't know if i would suspect the boost sensor to be the issue since it would affect the timing of all cylinders, not just 1 and 2. what indication do you have that 1 and 2 are not firing correctly? are they misfiring? what do the plugs look like (white/tan/black and dry/wet)? what is the compression of each cylinder (at operating temperature)?

are you saying that it runs fine except when you are at highway speeds/higher rpms? it could simply be a fuel flow problem since you need more fuel at the higher rpms. it may be a vacuum issue with the petcock system (otherwise known as the octy). or your floats might be set too low on carbs 1 and 2. could also be a vacuum leak at the intake boots, diaphragms, etc. hard to say without more info.

you could do a plug chop at highway speed to get some plug readings. run at constant speed and/or throttle position for 30 seconds or so and simultaneously pull in clutch, "chop" throttle closed and hit the kill switch, it essentially preserves the plug condition so you can read them. roll to a stop (somewhere safe, away from traffic) pull the plugs and visually inspect, or even better take a photo and post it here. white is lean, black is rich.

keep us posted.

cheers,

Trev

 

I would say you have carb issues and they need a more indepth cleaning. If it was ignition related the problems would be in cylingers 1&4 or 2&3, you said it was not firing on 1 & 2. The boost sensor sends a vac signal to the TCI to change ignition advance and that would effect all the cylinders.

 

On all the guidance from all I am pulling the carbs off now and cleaning the jets out to see if any are blocked. 1 and 2 cyls were wet after the drive last nite and not firing anymore. #4 seems to be running lean. #3 is good in plug color.Cold cylinder pressures low-130 psi and high 140 psi. spec says 148 psi, so the cylinders seem to be ok. There is spark on all plugs.
Wish me luck!!

 

Update: I have cleaned the carbs and reassembled them. All the floats are set at same height. Started it this morning and runs like a dream-very little choke needed to get it running. Test drive in about 4 hours to see how it performs now,probably a lot better since all cylinders are firing well.

 

Results of testing- Goes like a scared rabbit!!! runs smooth through all the gears and pulls like crazy. i had to be towed home due to trans/swing arm boot getting caught in driveshaft and destroying my ignition,sidestand,oil level,and neutral switch wiring that got wrapped around the driveshaft. New boot ordered and wiring is being repaired and rerouted by starter drive and under the air box to keep away from driveshaft. What a day!
Will still be able to make trip to Port Dover tomorrow.

 

Great that it runs well now. I want to know how the wiring got stuck in the driveshaft. Is the driveshaft exposed or was the u-joint boot missing? Lesson learned the hard way.

 

The boot was old and cracked with no spring retainers holding it on. I guess it flexed enough at speed to get caught by the driveshaft. The remnants of the boot spinning around caught the wiring and ripped it from its location.

 

Ouch, glad it did not get you.

 

It just tapped the back of my foot but didn't hurt me. I was able to get off to the shoulder and call CAA for a tow. I was only 3 miles from home. Should be good now. My neighbor made up a stainless shield to protect me from getting caught in the shaft. The replacement boot will take a few days to arrive. Still going to try for Dover.

 

Gave up on Dover, took car instead. fuel gauge had a bad ground wire and not reading on dash. The #2 carb float level was adjusted wrong and was leaking back to the air box. removed carbs and reset the float level on that carb and reassembled. Bike runs good now with no issues. I had it out on Sun and put on about 100 km with no issue-hooorah!!!

What should be the expected distance on a tank of fuel? 200-250 km?

 

That a trick question!

The answer is: It all depends!

Depends on how well you got her tuned-up.
Depends on if you are alone or with somebody.
Depends on traffic.
Depends on the weather.
Depends on the road.
You traveling in an area that gets revenue from speeding tickets?
Or, ... are you in the right lane of the Autobahn getting beeped-at for running flat-out and still not fast enough to use the left lane?

 

Well, I don't intend on beating it up too bad since it is my first bike and still getting used to the bike. Yesterday I was white knuckling the bars! I need to relax and get more comfortable on the bike. I don't intend on exceeding 110kph until then. My driving is out in the country at highway speeds between 80 and 100 kph. I filled yesterday on the first good run with bike on kickstand and the first bar yielded about 50 km. I hope to make average fuel mileage of 250 km/ tank at these speeds. I proably won't be able to push the 55mpg envelope like my brother's Honda F4i did since it was fuel injected.