only firing on two cylinders

hey guys,

rebuilt my seca over the winter, couldn't get any spark at all so i rewired the whole thing using the minimum wiring diagram.

now i can get it to fire on 1 & 4 only, no spark on the other 2 cylinders. if i swap the orange and grey wires to the coil packs, however, 2 & 3 fire instead. i have good continuity on both wires from the TCI to the coil packs, have tried a replacement TCI, and checked that both pickup coils will move the needle of an analog voltmeter.

please help me. i want to ride this beast. hearing it run on 2 only makes it worse.

joe

 

SLQGuy wrote a nice long ignition troubleshooting guide.

From his guide and your description, it looks like it could be a bad coil. You seem have eliminated the other potential issues, the pickup, and the TCI box, so that's my guess.

Chacal sells high performance aftermarket coils, but they are expensive and require modifying the bike to fit. I don't know where one would get OEM replacements. In any case, try SLQGuy's guide to check the coils. He seems to know what he's doing. I myself am just going by his guide, I haven't dealt with anything like this myself.

 

Vonder, Cam is right that Chacal sells the performance coils but I have the same bike as you and didn't have to modify anything. do yourself a favor and do one Final check. Leave everything where it is and just swap the coils. I agree with Cam that it's the 2/3 coil but swapping the Coil Only is the last thing you can do. While you're doing this troublshooting the non firing plugs are getting real dirty. I had One bad coil and chased my tail a bit from the dirty plugs. if you want to read my similar problem just search my threads. It was about 3 weeks ago (i beleive it was called confirmed confirmed and confirmed), you'll also see the Ohm values you should be seeing. the thing was, my coil pack Ohmed out Ok but was failing under load. Good luck

 

Swap the coils and give it a try

 

Right off the bat you know your coils are good. Swapping the coil input tells you that either your TCI isn't getting the correct input to fire off of or the TCI has a bad channel.

Since you have checked your pickup coils for an output, you have at least gone half the way on checking them. Can you tell if you have approximately 650 ohms across each of the pickup coils?
IF you have the correct resistance (should be ok up to 780 according to specs), your TCI is the main suspect.
I do offer a TCI refresh/repair service if this becomes neccessary, provided the TCI can be opened.
Let me know if I can be of further assistance.

 

Oh know I get it. Swapping those wires doesn't swap which coils fires which cylinders, it swaps which signal gets sent, right? Sorry for the bad advice then, vondeckerstein. Learn something every day.

 

hey guys,

I had tested the pickup coil resistance, and checked signal afterwards, trying to make sure that something was coming out of them.

I ended up driving an hour and a half last night down to weston, MO to highway 50 cycle, a salvage yard, and picked up ANOTHER tci. The more I'd checked the output of the two TCI wires, the more i was convinced both had one channel that was gone. They both gave strange output, one leaving +12 DC across the coil with the ignition on, heating the coil to skin burning hot before i caught it.

So, it fires on all 4 now(sometimes only 3), sounds sweet in the top end, but seems to bog easily down low and won't idle. It sounded real sweet around 3k or 4k but it seemed like cylinder 1 would drop out below that. I took it for a spin around the block last night to blow out the cobs before resigning to carb cleaning.

This is where the plot thickens.

The front forks, wheel, and brakes were replaced during the rebuild with the front end of an '87 honda hurricane. Initial impression of the steering is much better, but the brakes drag slightly, and during my test ride, the dragging got worse and worse, until i crossed into gravel, not realizing how bad it was, and the wheel locked immediately.

So, first thing will be these brakes, then hopefully I can get it to run for an hour or so around the country here and then see if the carbs need to be gone through.

Thanks for the help so far.

 

ooooohhhhhh yeeeeaaaaaahhhhhhhh

 

Swapping the coil inputs helps determine if the coils or the rest of the system is at fault. If you are firing 1-4 but not 2-3 and you switch the coil inputs, there are two results possible. Either the 2-3 input will fire the 1-4 coil pack with a no-fire result on the 2-3 coil indicating a bad coil pack, OR... the 2-3 input has no effect upon the 1-4 coil pack, indicating a problem further upstream. Either the TCI or the pickup-coil is at fault.
A quick resistance check of the pickup-coils (your use of an analog meter to observe the output is a VERY good idea to determine linearity of the pulse) will tell you if the problem is the TCI input or the TCI itself.
On occation, the TCI can give trouble with poor solder connections that the common layperson can repair themselves easily by reflowing the joins.
Good luck all!

 

or in my case. the chip went bad in my tci.

 

Sorry to butt in but how do you test the TCI to see if it is good?

 

Swap it into another bike, or swap with a known-good one.

It's about the only blasted component on the whole bike you can't really TEST test.