Diagnosing #4 cylinder not firing

[videoarizona]

I did pull the TCI out of my parts bike. I have not done anything with it... But thought about Cleaning it up and seeing there was a difference. I looked and have not found directions on removing the coils.... Unless the only way is to remove the whole fairing. I was told to try and switch the plugs and wires from the 2 and 4 and see if the dead cylinder moves or not... So might try that.

 

 

First, I wouldn't think of pulling coils yet. Just look at the wires for corrosion. Pull plug wires one at a time and check ends for green corrosion. Swapping 2&4 wires is good idea.

 

Take apart parts bike TCI and look over the circuit board and connectors. Research tci's here on forum and look at pics of bad boards... Familiarize yourself with bad parts so when you pull yours you can know if it's good. You could also make any repairs on parts tci so you know you have a good spare.

 

Do only one thing at a time then test. You will figure this out. Just need patience and persistence.

[videoarizona]

Ideas:

 

http://www.venturerider.org/forum/showthread.php?127732-Disassembling-TCI-Box&highlight=diodes

 

http://www.venturerider.org/forum/showthread.php?77989-In-regards-to-refurbing-a-TCI-box&highlight=diodes

 

http://www.venturerider.org/forum/showthread.php?120802-Intermittent-spark-one-plug&highlight=diodes

 

http://www.venturerider.org/forum/showthread.php?115528-TCI-repair-SUCCESS-sort-of&highlight=diodes

[snyper316]

What got me on his bike is you could smell gas on the plug it had some black on it. But when we put the colortune plug in it only showed white spark when we would rev it you would see flash of orange. Would have helped if my multimeter wasn't hiding in plain site... Doh!!! Could have checked his TCI like planned. Of course that's the way it goes when your not looking for something it is right there......

 

Sent from my LG-K371 using Tapatalk

[mcompton1973]

Seems like the logical step. Take the #2 plug wire and connect it to the #4 coil, and #4 plug wire to the #2 coil.

If it is coil/TCI related....the 'cold' cylinder would move to the #2 and the #4 would be normal.

If it is carb related....the #2 would be hot and normal and the #4 would show no change.

 

The problem is....I dont see how to get my wires to reach to the other coil.

Would I just need to buy a couple 'universal' wires to make it work? and if so...what specs do I need to look for?

[snyper316]

Seems like the logical step. Take the #2 plug wire and connect it to the #4 coil, and #4 plug wire to the #2 coil.

If it is coil/TCI related....the 'cold' cylinder would move to the #2 and the #4 would be normal.

If it is carb related....the #2 would be hot and normal and the #4 would show no change.

 

The problem is....I dont see how to get my wires to reach to the other coil.

Would I just need to buy a couple 'universal' wires to make it work? and if so...what specs do I need to look for?

 

Ok so here is what you do take the number 2 pigtail and unplug it and plug it into number 4 and visa versa so basically your just changing coils.... but not moving nothing.... just switching power supply to coils...

[snyper316]

Ok so here is what you do take the number 2 pigtail and unplug it and plug it into number 4 and visa versa so basically your just changing coils.... but not moving nothing.... just switching power supply to coils...

I would like to add I think.... not 100% sure but that what it sounds like I could be backwards again today...

[bongobobny]

No, it would mean you are swapping both the inputs to the two coils AND the outputs as well, so now coil 2 thinks it is coil 4, and vice versa. It is the same as swapping the physical positions of the two coils but instead, you are swapping the wiring for both coils. As stated, this will cause the opposite cylinder to go dead IF the problem was the coil and/or TCI...

Jus

t remember to switch the plug wires going to the plugs as well as the input wires going to the coils. There should be enough slack in the harness, but if not then yes just Macguyver a couple of extensions up.

[mcompton1973]

yeah, if I just change the harness wires...it would tell me if there was an issue with the TCI maybe...but a bad coil would not move because the wire coming from the #4 coil would be going to the #4 cylinder still. So it the coil was bad, I still would not know. I do NOT have room to move the wires from one coil to another side...so I will need to buy something I guess. What Ohm????

[mcompton1973]

If you have not noticed...I dont have a ton of time to mess with this bike. Starting to frustrate me. I want to ride. Uggg. Someone wants to spend 1750 they can get it...my parts bike....and my 83 with no title.

 

Ok. Heres the deal today. I tried to swap coils on #2 and #4 . I got a universal plug wire kit. Ran #2 coil to #4 cyl. Ran #4 to the #2 . Could not really get it to start. Didnt make since to me. Figured if coil or TCI was bad...would start and the #2 cyl would be the one not firing right...if it was carb related would start and #4 would stay not working right.

 

Put things back the way they were...still isnt right. Not starting...or will start...idle like crap and die if you try to give it fuel.

 

Recorded a short video.

[BlueSky]

Did you switch both coil leads, input and output?

[CaseyJ955]

I think there will be a comp test. When I had mine on 3 cyl it was nothing like that. It was a little hard to tell there was a problem. I suspect the parts bike may become instrumental in solving this mystery.

[mcompton1973]

Did you switch both coil leads, input and output?

 

I just took coil output from 2 to 4. I guess inputs should have changed because of timing. That said...why is it bad once i out bacj the way it was?

[videoarizona]

I just took coil output from 2 to 4. I guess inputs should have changed because of timing. That said...why is it bad once i out bacj the way it was?

 

 

Couple of possible reasons.

 

By not changing both inputs and outputs, you may have done something to motor. Doubtful as the timing didn't change just ignition. Ie, never mind.

 

In making the swap you damaged an already damaged part just a tad more...like a plug wire. By moving it around, if it was bad to begin with, it could be worse now.

Or one of the wires isn't in the coil all the way. It needs to be pushed in and then held in by the rubber o ring and finger nut. Or it's broken at the plug cap. Or green with crud on the end. Plug caps can and do go bad as well.

 

If you haven't changed wires and caps in a while that would be my next move. I bought a set online that fit perfectly and were the proper resistance for our TCI. Think they were tested at 5K ohms. Said so on the package.

 

Coils do go bad but not that frequently. If you live in a wet area, pull the TCI out from under the coil area. Lots of cable to let it sit on the air cleaner. Search the older posts...lots of pics and info on cleaning and checking the TCI. Including posts on how to get it apart and check the diodes. There is a diode for each cylinder that can get grungy and die.

[mcompton1973]

I did not think about the wetness. I actually had the false gas tank cover off the bike and it got rained on this weekend. Wonder if that could be part of the problem. Also possible from your post that I did not get the wires put on the coils properly. I kind of assumed that as I screwed the cap on it would pull the wire into the coil enough, but now that I look at it a little closer I see that would not be the case. So I probably need to redo that experiment completely after few hot dry days. I'm also going to go ahead and get a compression tester and check compression on All 4 cylinders. I think those two things will give me more information.

[bongobobny]

Every time you pull a plug wire from the coil, you need to trim about a quarter of an inch from the wire to ensure a good connection from the coil to the wire...

[mcompton1973]

I got a compression gauge from Autozone today. This weekend I will pull wires again. trim ends. Make sure that I am getting good connections at the coil, and swap the coils again and the leads going to the coils.

 

BEfore I do that, I will make sure I can get good compression on all 4 cylinders.

 

Thanks for the help, I will keep you posted later this weekend

[mcompton1973]

Pulled the wires off the 2 and 4 again. Trimmed them...did what I could to make sure they were actually connecting at the coil. No difference.

 

Now...I DID have the bike parked for a week with the fake gas tank off, and it rained once. All the fuses, main fuses etc all look fine.

 

I have a charger on the bike because the battery was low from trying to start it so many times.

 

One thing I noticed today. There is no Tach. Is that significant? I had tach working fine before. My last ride the odometer was not working...but the tach was fine. Now even when I do get it started, there is no tach...and it sounds just like the video I posted last week.

 

I want to get it back to running on the 3 cylinders at least the way it was so I can do compression test, and then if that is OK, I will go back to TCI?Coils as a possibility I guess.

[videoarizona]

Tach not working. Driven off of cyl #2 . Then #2 coil not working or bad connection to coil, or connection loose.#2 is left front.

[mcompton1973]

OK. That makes a lot of sense then. I must not have gotten the # 2 hooked back up right still. I will go mess with it some more.

[mcompton1973]

Tach not working. Driven off of cyl #2 . Then #2 coil not working or bad connection to coil, or connection loose.#2 is left front.

 

Is it possible that I messed up a coil just by taking spark plug wires on and off? I went out and tripple checked that I had good connection to the #2 . I used a different cable. I am getting no spark through the #2 now. That is what is causing the hard start. I am basically running on only 2 cylinders now.

 

TCI? Or Coil? or what would you do/check next?

[bongobobny]

OK, the tach is driven by the input to coil 2, specifically coming from the TCI to the coil. So, even if coil 2 went bad it would not effect the tach. Check for corrosion on the connector on the TCI...

[mcompton1973]

OK, the tach is driven by the input to coil 2, specifically coming from the TCI to the coil. So, even if coil 2 went bad it would not effect the tach. Check for corrosion on the connector on the TCI...

 

OK. I have another TCI, it came off a parts bike so I do not know the overall condition of it. I am thinking that I could remove the airbox, remove connectors to the TCI and mount new one on top of airbox (which everyone says I should do anyways.) Do you guys typically just put some velcro tape on it and on the airbox to hold it in place or what?

 

Like I said, I did not ride it in rain, but it did rain when the fake gas cover was off, so maybe got moisture in it???

[bongobobny]

You may have to cut/break one mounting ear off to get it to fit. I used a self-tapping bolt and bolted it down on my airbox...

[videoarizona]

Is it possible that I messed up a coil just by taking spark plug wires on and off? I went out and tripple checked that I had good connection to the #2 . I used a different cable. I am getting no spark through the #2 now. That is what is causing the hard start. I am basically running on only 2 cylinders now.

 

TCI? Or Coil? or what would you do/check next?

 

 

Mr. Bongo has it right. It's the input to the coil...the little wires that come from the TCI. The problem will either be in the TCI, the connectors at the TCI, the wires going to the coil from the TCI or the connectors at the coil from the TCI. That is the drive for the tach. No ground pulse from the TCI to the coil, no spark. (think that's right) Little fuzzy in brain tonight. Got back home after a long weekend away only to find the air condition dead....no air handler fan. Poor compressor was running for I don't know how long....doing nothing. 88 degrees in house....going to be a long night...

 

Ugh...