Limped home tonight

Hi there, I searched for a similar post but couldn't find anything relevant.
I was driving along and the bike suddenly died. It would idle but the rpms wouldn't go over 2000. After a couple of miles of doing 30 mph it would pick back up and would work normal for a couple of miles and then do the same thing. When I got home I started it and tried the spark on each plug. all plugs had spark but when I gave it throttle the motor would stumble and I would loose spark. The tach wouldn't even work.
The valves were just done and the carbs were synced and cleaned. The battery is new and fully charged.
This seems like a problem in the electrical system before the coils since all cylinders are loosing spark.
Any ideas??? Possibly the stator??? Thank you

 

Seems more like a fuel flow problem. I would inspect the petcock and the fuel shutoff diaphragm, check the vacuum line and fuel line for kinks and cracks.Rreplace or rebuild and parts that you find questionable. Also check the fuel cap, there is a vacuum check ball in there that can get stuck and prevent fuel from flowing.

 

Sounds like a loose connection. Makes contact sometimes but just enough wiggle to not make all the time. Start at the battery and carefully check the tightness of the connections. They don't have to be loose, just "not tight enough". The trick is to not go too tight and break things. Glass fuses sometimes have the soft wire inside come loose and not always make contact. Try rolling them gently in their contacts. Corrosion is insidious and sneaky and hard to detect lots of times. Methodically work your way thru checking, wiggling, tightening and rechecking. Maybe something as simple as wiggling the key in the switch or the kill switch. There are numerous finicky interlocks to wiggle as well, the sidestand, the clutch lever. When you find it it will seem simple, frustrating until you do.....

 

TCI starting to fail when it gets hot enough.

See if it does it when the bike is cold and you start out for a ride. Does it start after awhile (as in.....long enough riding for the tci to get hot enough to start breaking down) or does it happen right from the get-go in the morning when the bike is cooled right down?

Dave f

 

Wow! Three responses and three different diagnoses! Welcome to the reality of your symptoms being multiposed.

Considering the fact that it ran fine after the issue cropped up the first time I would rule out fuel issues (unless you don't have an in-line filter or you have bad gas (or both)). I would bet you have electrical issues as well, and first place to look would be your coils, since you can easily test them with a primary and secondary resistance test. If they check out, suspect your TCI. It wouldn't hurt to go through the whole system and make sure you have good contact everywhere

 

As mentioned earlier...check for loose connections. Paricularly battey leads.

 

Thanks so much for all the ideas.
I'm quite confident its an electrical problem due to the fact that the plugs were soaked from holding the throttle wide open all the way home. I'm going to do some testing after work and I will report back.
I've had an on going problem with this bike since I got it in the spring with it not wanting to start when hot. I was assuming it was a gas problem and did everything the forum suggested. I had always suspected it was electrical from having old snowmobiles which did the same thing. 340 Olympics were famous for coils. lol

 

And cross "stator" off your list. Alternator brushes do wear out; but the bike runs off the battery. The charging system charges the battery; below 2200rpm it's all on the battery.

Do you still have your original fusebox?

 

No fuse box, several in line fuses under the seat

 

might also pay to have a look at the plug connectors and caps, slight vibration when running could also cause similar problems as described if caps not screwed on tight.

 

I hope you may have the answer. I found 2 caps that were very loose and it appears that 2 caps are bad. Sometimes I can get a good resistance of 4.5 ohms and later I will try and get nothing, meter will just show 1. I tapped them on the floor and tried again, this time 4.5 again. I'm going to pick up a couple of new ones tomorrow.
I tested the coils and they are both showing around 12k without the caps.

Here's a question though. Are the plug wires meant to come out of the coil body?? I was getting readings all over the place on one when I would move the wire @ the coil so I figured I had nothing to lose. I pulled it out and saw corrosion inside on the pin. I cleaned it up best I could because it is in deep and re installed the wire. Now I have a good stable ohm reading and it seem tight. just wondering.

 

Oh, I also took every connection apart on the bike and found a lot of corrosion. I used electrical contact cleaner on them. Any one of these could have played a part with my problem.

 

I came across the same problem with my bike, but it was also causing overcharging issues. It pays to re-crimp the connectors with new 6.3mm spade terminals. That way you have eliminated a future electrical problem for another 30 years.

I had good luck with Cycle Terminal's 16-20 gauge tin-plated connectors or you can contact xj4ever.

Crimping howto: http://www.xj4ever.com/crimping%20my%20style.pdf

 

Hi Jay; OK, the plug wires are NOT supposed to come out of the coils. If you actually pulled one out, more power to you; I hope you lopped a few MM off before re-installing so that spike could get a fresh bite. If it can be gently pulled back out, do so and then "glue" it back in with a smear of RTV on the outside of the wire, after carefully slicing 1/4" or so off the end of the wire.

RE: banging the plug cap on a hard surface and it suddenly changes readings:

INSIDE the plug caps are resistor cores that screw in. If you look in the hole where the spark plug goes, you'll see screwdriver slots on each side of the hole. You can use these to gently tighten the resistor core in the cap; they tend to work loose. You can slide the rubber boots off the plug cap to get a better look.

The plug caps themselves have spikes that screw into the center of the wire; so before reinstalling a plug cap lop a couple MM off the end so that the spike gets a fresh "bite" into the wire.

 

Jay,

follow fitz's advice with caps, cleaning all electrical connectors is also a good starting point.

Most of these bikes have sat in a yard for some part of their life! So corrosion is found where ever you look.

Good luck and keep us updated as it helps others in resolving their problems as well.

 

:evil:
Well I was really hopeful the two bad caps were the problem so I finally made it to the closest shop which is 100kms away and picked up 2 new caps that I probably didn't need if I had of read the comments before I went. I didn't know about the resistor in the cap. Probably just needed to be cleaned and snugged up. Anyway I installed them and took it for a quick blast and it worked great as it always does when you're only a couple of minutes from home. Called my buddy to head for a spin and got my wife geared up to come along and off we went. I got 2mins down the road and it cut out again. I whipped it around and took it home. It immediately started working when I pointed it towards the house!! I guess I need to do some tests on the TCI and will report back.

 

Just eliminated another couple of possible causes, I disconnected the side stand relay which had some water in it and went for a shot. First 15kms were great and then blaaaaaaaaaa, same thing. I turned around and after a short distance it reconnected and was fine to get home.
The second thing I eliminated was my wife being a jinx, she wasn't with me this time.
I saw on another forum that when the break down happens, the bike keeps running but the tach goes crazy showing 0 rpms even though its still running and jumping up and down. They thought this was a sure sign that it was the TCI.
Any thoughts on that one???

 

Took the cover off the TCI and it had corrosion on the bottom of the circuit board. So now I'm working on finding another one.

 

Don't throw that one out. It might be able to be saved. Clean the corrosion, retouch all the solder joints, replace any caps that are bulging or leaky (better to replace them all, but it's time consumng). In any case, save it for later salvaging.

 

I bought one on ebay, just need to wait now.