HELP! XJ1100 dead!

[bkush]

Everyone, I've been having a weird problem with my XJ1100. Up until a couple weeks ago, it's been a great bike, just purring like a kitten. But, a couple weeks ago it started losing power. As I was going down the road it would lose half or more of it's power. Almost like it went down to 1 or 2 cylinders. I managed to limp home that time, but I had to run it up to 5k and feather the clutch to take off from a stop. And, it was intermittent. The next day it was fine.

Today, same thing happened as I left work. I limped my way towards home, but about a mile from my house, it flat out died! I pulled in the clutch and coasted then let out the clutch and it fired, but when I tried to give it more throttle, it died again. Eventually I came to a stop. When I tried to restart it, it would catch but then die. I repeated this until I used up the battery. Another thing I noticed, before it died, it was backfiring as I limped along. It also smelled strongly of gas. The backfires were not loud, but they kept going, maybe 5 or 6 times.

I'm running stock carbs with the octopus and I'm sure the fuel lines are run correctly. The spark plugs look "normal".

Any ideas?

Bill

[Ken Talbot]

Pick-up coil wires. Check the tech section for one of the most common problems with these bikes.

[Jerry]

Uh, Ken, its an XJ....no pickup wires.

As with all electrical problems, which I belive this to be, there can be a few different areas to look at.

From a recent post:

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The XJ has a few circuits not found in the XS. Two circuits specifically are designed to keep the XJ from starting.

First one is a side stand switch. Designed to keep you from riding off with the kickstand down. This switch is no longer available from Yamaha as a replacment part. Wire from it has 3 connectors and connects to the main wiring harness just behind the tank. I would unplug the switch and connect all 3 bike-side connectors together. This makes the circuit think the stand is always in the up position and will allow the bike to start if this circuit is the culprit. Be aware this will also allow you to put the bike in gear and drive off with the kickstand down, which some of us have done over the course of our riding careers. It is dangerous.

Second circuit is in the clutch lever assembly. Note there are 2 wires that go into the casting; there is a little pin switch in there. Idea was to keep you from starting the engine if the transmission was in gear and the clutch lever released. Work around is to track the 2-wire cable into the headlight bucket, unplug the cable, and put a jumper across the bike-side connector. This makes the circuit think the clutch lever is pulled in, and allows the bike to start.

There is a Search tab at the top of your message screen, type in fuse block replacement and look at the many, many posts on this topic. Going by your description, I would consider the fuse block a must-replace item. It will cause you all kinds of grief until you get a working block in place.

It is very common for a block to look good and yet be bad; the fingers that hold the glass fuses simply loose the ability to conduct electricity.
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If the bike will crank and not fire, check the two circuts mentioned above. Another area is coils; there are 2 of them, each firing 2 cylinders. Would be unusuall for both to go bad at the same time, but your original description of loosing half you power could be an indication of a bad coil. Is your bike firing on 2 cylinders at all when you try to start it?

Have you replaced the fuses or fuse block? Fuses can look good and be bad, same applies to the fingers that hold the glass fuses in place. A bad contact can cause the intermittent problems that you describe. More likely and far more common than a bad coil.

Any more info you can supply would be a help. Good luck.

[bkush]

Jerry, I looked at the tech tip that Ken suggested, and noticed that it looked a little different than my XJ, specifically the two dark gray stationary things (magnets?). I thought about the kickstand relay and the clutch switch, but dismissed them because I thought both of them would kill the engine immediately, or am I missing something?

An update: I recharged the battery and it cranks and starts no problem, but if I give it any throttle, it dies. I was starting it in neutral with the kickstand down. And, as I was testing it, I could tell a difference in the sound of the engine. It really sounds like not all of the cylinders are firing. But then, after I gave it throttle and killed it, I started it again and it sounded normal.

Bad ingition coil?

[bkush]

More info... When it was acting up, I could keep it running, but I had to run it at much rpm's than usual. If I let it go to idle, it would die. I have replaced the fuse block.

Thanks

[trbig]

It sounds fuel related to me. If you get it started.. spritz some water on your header pipes after a 30 seconds or so.. see if they all sizzle equally. You will be able to tell which ones are firing pretty easily that way. Then after you find the ones that aren't firing.. take the spark plug off one at a time to those 2 cylinders and ground the plug to the engine with the wire connected and see if there's a good spark. A bike will pop and sputter like that as it runs out of gas. But it could also be electrical and burning the raw fuel not exploding in the cylinders.... down in the pipes.

If you find it's fuel related... my opinion is first thing... get rid of the octo! That will eliminate a lot of the guess work. After it's out of the way, you can attach some clear lines to your drains on the botoom of your carb's float bowls. Turn your fuel on and loosen the screws and let the bowls drain into a jug. If you seem to be getting plenty of fuel from all four, it may be the other extreme and you may have a float staying open and flooding things... but you would have some black plugs I would think.

Tod

[Ken Talbot]

Originally posted by Jerry
Uh, Ken, its an XJ....no pickup wires.

Oops.

Step 5 of the "engine will not start" diagnostic in my XJ shop manual says to check the pick-up coils for resistance. I just assumed these coils must have some sort of wire leading to the primary side of the coils, and that even without all the flexing of a vacuum plate, they might still be subject to vibration and failure. Maybe a dirty or loose connection instead?

[Jerry]

Ken:

Could be a bad pickup coil, but would be a rare occurance for one of these to go bad.

Bkush:
Another thing to look for is something Yamaha called the Boost Sensor. On the XJ, the boost sensor is a small black box under the gas tank. It has one vacuum line going to the #2 intake manifold IIRC and a 2-wire connector that goes into the wiring harness. Purpose was to convert a vacuum level into an electrical signal that the 'black box' (TCI ignition) used to determine the spark advance. However, from personal experience, the 'fail' value, even iif you take the sensor out of the circuit, will allow the bike to run but with a loss of power. It won't cause the bike to quit. Check the vacuum line for breaks or leaks (same with all vacuum lines, btw) and make sure the wires are not crossed or shorted. If you replace any vacuum lines, make sure you get vacuum hose, not fuel line, for doing the replacing.

On earlier XS11s, and the tip that Ken mentioned, there is a mechanical advance under the left-hand engine cover, The constant movement of that plate eventually breaks the fine wires Yamaha used in the assembly, thus is a known problem with the mechanical-advance mechanism. In '81 and '82 Yamaha replaced the mechanical system with an all-electronic version. While the later 2 systems are not the same, both depend on a boost sensor to, in effect, provide an advance signal to the ignition system.

I would check all your fuel lines. As they age they swell internally, shutting off fuel flow. Different stuff is available; I happen to use a light-blue snowmobile fuel line as it has a smaller outside diameter and seems to fit better in the cramped spaces between the tank and the 'octopus'. You might also want to change the lines between the octo and the carbs as well. Any good quality fuel line will work; the synthetic stuff is more expensive but is more flexible and less prone to kinking.

The Octopus is a safety device. It uses engine vacuum to turn on fuel flow to the carbs; when the engine is off no fuel should flow. It was assumen that in an accident or lay-down the engine would quit,. fuel flow would be shut off, and there would be less chance of a fire or leaking fuel on the engine. The petcocks have a "PRI" position which bypasses the octo, try setting both petcocks to this position and see if the problem goes away or gets better. If the problem remains then the octo is not your problem.

Another area which some have reported to be a problem is the kill switch. A bad wire or dirty contact can cause some strange problems.

I am leaning to fuel delivery problems if the bike starts and runs OK at idle. I would try replacing your fuel lines and using the PRI setting on the petcocks to see if thing improve. One note....the routing of the fule lines is a bit strange. Either tag the old lines or replace them one at a time to make sure you get them correctly routed and attached. There is a routing diagram unther the XJ seat that may help.

Let us know what you try and the results.

[bkush]

Another update: Today, I got it started and let it run for just a minute or two, then killed it. The two outside pipes were too hot to touch, but the two inside pipes were just barely warm. I removed the two spark plugs on the left side (as you're sitting on the bike). The outside plug was black around the outer rim but whitish tan on the eletrode. The inner plug was black and wet everywhere. I was able to give it some throttle, but it was flaky. I got it running at about 4k and took off the choke and it died.

Does this confirm carb problems?

[John]

It's looking like a coil, coil wiring connection, or a pick up coil are at fault. #2 & 3 are fired by the same coil, and they fire at the same time.

[Jerry]

Actually it indicates an electrical problem. On these bikes, #1 and #4 fire from the same coil. #2 and #3 fire from the other coil. It sounds like one of your coils is bad, or you have a wiring problem with the coil that fires #2 and #3.

It is possible that 1 bad cap can also cause problems. If you do a search on Coils you will see many, many threads on this subject. Two in particular that you should read:

How to replace your stock coils with Yamaha XS 650 coils:
http://www.xs11.com/forum/showthread...ighlight=coils

Then there is the Coil FAQ:
http://www.xs11.com/forum/showthread...=&threadid=583

You can 'swap' coils and see if 2 and 3 are hot after running and 1 and 4 are cold. That would be almost 100 percent proof the problem is a bad coil or plug wire.

[DELL82]

Had a similar problem and found the 5K resistor in #2 and #3 were bad and being jumped around( arcing/carbon), very poor and intermittent spark. Replaced resistor with brass rod same length and diameter. problem solved. Since then I (using a Dremel with dentist bit) replaced #1 and #4 by routing out the resistor and jumping around it with high temp solder( 900 degree). Spark improved dramatically with resistor out.

[bkush]

Okay everybody, today, I was going to take the tank off and check and possibly switch the coils. I started the bike up, it sounded ok, and all pipes were equally hot after a couple minutes. I turned off the petcocks to dry up the fuel lines, and now, 5 minutes later, the bike is still running?!! I have both petcocks on OFF. How can this be?

Bill

[John]

Originally posted by bkush
Okay everybody, today, I was going to take the tank off and check and possibly switch the coils. I started the bike up, it sounded ok, and all pipes were equally hot after a couple minutes. I turned off the petcocks to dry up the fuel lines, and now, 5 minutes later, the bike is still running?!! I have both petcocks on OFF. How can this be?

Bill

They are leaking?!

[Jerry]

Takes longer than 5 minutes at idle to burn all the fuel out of the carb bowls.