no spark.

[reece]

iv read threw some of the previous post to make sure this wasn't already covered.
ok so i bought a 81 xs400 and it was not in running shape. took it home cleaned carbs changed oil and plugs new gas. started backfired and wouldn't start again. checked plugs again and i had spark so i checked coils primary and secondary just to be sure also checked wires. then i checked the valves and readjusted to spec checked compression and timing all checked out OK tried starting it again and backfired than no spark went back thew and checked ignition system again and still checks out fine so im suspecting "cdi" any ideas or input?

 

[Scorpio1963]

Check all your fuses and ground wires and connections.

 

[63-Coupe]

Check the battery in case you drained it trying to get it going. You need a battery with a decently good charge or you get no spark on these.

 

[Lou Ranger]

Yes, exactly what happened to me. Unless it stated on the very first revolution, the battery was too weak to supply a spark - even though it would still turn the engine over. For weeks before getting a new battery, I would jump start it from a detached 12v car battery. Lots of juice for a spark, and it would start easily.
Before tearing anything apart or buying anything new, try jumping it to see if it's just the battery.

 

[arfstrom]

So, when you cleaned the carbs, which method did you do? It took most of us 3 times to take off the carbs, clean em, and get them functional again. My method was the boiling lemon juice.
Tobie

 

[reece]

Well the carbs arnt really the issue because i have no spark. But i took them apart and cleaned everything with carb cleaner and set everything to the recommended setting i found on here. And the battery i was using had a good charge..i also went threw and cleaned all grounds and connections and still no spark im ordering a "cdi" tomorrow hopefully will have it running soon. Thanks for the input

 

[16VGTIDave]

LOL! Every other new XS owner has said the same things, myself included! I seriously doubt your carbs are clean enough unless you completely stripped them down, probed every passage with a fine wire, blew them out with compressed air from both directions, and then used an acidic cleaner to remove any remaining corrosion. These carbs are made from a Zinc alloy and corrode very easily. The small passages get restricted or plugged with corrosion.

It is not common for the TCI ignition to have problems. Sure, some TCI modules fail, but not many. You can change as many "cdi" things as you want, but until you actually find the problem, you will just be throwing money at your bike. If your bike was backfiring through the carbs, you have spark, just not at the right time. Or a very lean mixture from plugged carbs. Are you sure you have the spark plug wires on the correct cylinders? Are the spark plugs new? Did you try boosting the battery from a car, with the negative cable connected to your engine? Was the bike in neutral when you were trying to start it? Have you run through the troubleshooting procedure in the manual?

 

[XSLeo]

As mentioned you can through as many "CDI" parts as you want at the bike but not a one will help. Reason being the XS400 did NOT use a CDI, it uses a TCI. Both ignitions but very different.
Leo

 

[reece]

yeah im new to motorcycles but im very familiar with cars / trucks. I have a associates degree in automotive and 3 ase's. i put cdi in quotations because that's how i keep seeing it referred to as. but like previously stated the wires plugs and coils tested fine and the voltage stoped when i back probbed the "cdi" harness but it had power going in. so i wouldn't say im "throwing parts at it". i was just wondering if someone had any helpful incite.

 

[Lou Ranger]

... i was just wondering if someone had any helpful incite.

I was talking just last night to the friend who bought my 1981 Yamaha sr250. He and a mechanic trouble-shot every conceivable thing and finally they came to the component that never fails - the cdi (or maybe it's a tci - I don't know). It had failed. A $50 used 6 connector cdi unit from a boneyard plugged into his 5 pronged plug and the bike runs like a charm.
Hope you are just a lucky.

I can't pretend to have a clue about what they are, but here are some excerpts from a site about ignitions which I found. All I know is that I used to hate points and condensors on my Morris 1100, my VW KarmannGhia and my Kawasaki s1a250 and I loved it when "Breakerless" ignition was invented, whatever the type.
---------------------------

"TCI" is Not "CDI" ... TCI uses transistor switches to disconnect the coils. This causes a charged coil to collapse and "fire" the spark. This is known as "Kettering" or "Induction" effect.

CDI systems use a different technique. While the pickup and triggering is the same, the output from a CDI ignition module is a short high voltage pulse to the coil. In a CDI system the coil doesn't store the spark but instead AMPLIFIES the pulse from the CDI unit to a much higher level.
The higher output voltage of a CDI module produces a much higher cooresponding coil output voltage . So, CDI produces a much hotter cleaner spark. It is the ignition of choice among race teams and now widely used for everything. The "CD" in CDI means capacitive discharge.
The downside to CDI is the short high voltage spark pulse duration. This is better at high RPM but makes starting difficult ... TCI produces a longer spark duration (which some might argue is more reliable).
​

 

[crashcourse]

It's not just checking the coils but making sure you have voltage at the coils. If its not even getting power then a new TCI won't help, but if you do have power at the coils and everything downstream checks out, then the TCI just might be the problem.

 

[16VGTIDave]

i was just wondering if someone had any helpful incite.

Absolutely! But since you aren't answering the questions before you, why don't you put your education to use and determine why you were asked questions. The answers you seek are in the questions...

Posted via Mobile

 

[arfstrom]

I have been chastised about my method of checking for spark, I got lucky, Our raining Dr. Drewpy stops by every now an then an blows us away with simplicity of our problems, I had admitted to testing for spark by pulling the plugs out, and cycling the motor, I had a problem between one cylinder running and not the the other. So I reasoned if I see spark I must be fine, then Dr said, I am going to kill my TCI, Or SDI what ever it is. So I stopped doing it, my fix for that has been New wire, plugs, and cap. I Have been running fine since, (with a few exceptions). so that tends to be the path most of us web base trouble shooters go for,
1. Clean Carbs 3 times. Use more than one method,
2. Protect your carbs, put a inline filter.
3 refresh the cheap stuff, Plugs, Caps 5k, wire generally less than $10bucks. (Trim the wire both sides to get a fresh cut on the old coil/cap connectors) sometimes the plug wires spread out too much, and carbon up I suppose (Guessing)
4. validate wiring. Our bikes are 30 yo, Stator was meant only to last 10 to 15 years till the wire goes to HeII, Starter button falls out after a bit, and then grounding gets bad, just a minor cleaning.
5. Oh yeah the manual is jacked up about the Float settings, validate the right settings by double checking various threads here. Its past my bed time, I not looking it up right now.
6. Practice safety. Most of my troubles was cause by me. being stupid. thankfully I know when to stop, and take a breather.
7. Quick LED update that effects nothing else, Is to swap LED only for the Brake lights. Turn signals going to take some figuring out.
8. don't Kick start your engine with the side panel off the bike. You will learn more that you ever wanted to know about the transmission, and the selector. that is basically everything I have learned with out looking up a thing. Good night guys
Tobie
PS Welcome to the group! Reece, Look forward to finding out what your bike issue is!

Dont forget to check for valve spacing I Forgot the term, it will pop up in a minute, Head valves? exhaust valves, Where you use the feeler guage, Ohh good night