88 virago 750vx coiling not giving spark

[rayillu ()]

Let me start over..... what I wrote hurriedly didn't make much sense...

My 88 virago vx750 is running on one cylinder.  The coil for the rear cylinder is firing but not the coil for the front.  I swapped the front cylinder coil out with another used one and still no spark.  I swapped my good one for the rear cylinder  with another used one and took my good coil and used it for the front cylinder and still no spark.  I know that coil is good.  I have checked my wire connections and all looks good.  Can anyone help as I don't know where to go from here. Thanks.

Ray

[bstig60]

R U sure you aren't getting spark or is the cylinder just not firing? If you know you are not getting fire, then check the TCI. It could have gone bad. The only way to check it is with replacing it with a known good one. Otherwise, it could be not getting gas or a burned or leaking valve causing loss of compression.

Bill

[rayillu]

yes, it is my other coil which is good.  I switched it over and put a replacement where my good one was.  Is the TCI the ignitior box bolted to the rear fender?  Thanks.

Ray

[bstig60]

The TCI is the igniter box, but I am not sure where it is located on your model. I think it is behind the battery box next to the rear fender. It will probably be a black box with two connectors on it. Don't forget to check the wiring with a volt/ohm meter before you blame the TCI. They are not easy to find and new ones are expensive. Are you sure you are getting fuel?

[rayillu]

Yes, I am getting fuel. For the longest time I thought it was a fuel problem because I know the carbs needed a rebuild. After I had the carbs rebuilt the problem was still intermittent so I thought it was the fuel mixture so I took a long time to get that right but even then it came back and wwas intermittent again. Now it is always firing on one cylinder. I will check the wires with the meter before I invest in the TCI. Someone also suggested that I might have a break or a splice in the harness for that coil that has come loose or got disconnected. Do you think that is a possibility? I was going to open up the harness and have a look. Thanks again.

[bstig60]

Good suggestion! However, it probably isn't necessary to open up the harness unless you have better evidence there is a problem inside it. If memory serves, the Orange wire is the one from the TCI to the front coil. Verify the color on a wiring diagram for your year and model bike. When you determine the correct wire color, check the continuity with your ohm meter. Also check to see if it is shorted to ground by putting one lead on the coil wire and the other on the main battery ground where it it attached to the frame. When you are checking the wiring harness, make sure you have the positive cable of the battery disconnected and both the coil and TCI unplugged from the wiring harness. Otherwise you may get a false reading. Also, try moving the harness around when you are checking it with the meter to see if the reading changes. What kind of plugs are you using? Where is the battery ground connected to the frame on the bike? The reason I ask is 2 fold.......... NGK plugs are notorious for fouling and causing misfires. I advise using Autolite AP63 Platinum's gapped at .028 thousands. There has been a grounding issue with Virago's that has created a lot of intermittent problems...... From the factory, Yamaha saw fit to connect the battery ground cable to the bottom of the Aluminum battery box on some models. It should be connected to the steel frame. This change alone has solved a lot of intermittent electrical problems.

[rayillu]

You're memory does serve you correct. The orange wire does go from the front cylinder coil, which is not working, to the TCI.  I moved the battery ground wire from the aluminum engine block to the frame.  I am using ngk spark plugs and will pick up the autolites.  I haven't done the ohm meter thing yet but hopefully will get time tomorrow and let you know how I make out.  Thanks for all your help.

Ray

[rayillu]

ok, here we go....I'm not sure what these readings me....can you explain....looks like something is up with the gray shorted to ground?  I really appreciate your help.

orange wire is for the rear cyl coil and it has good continuity with a reading of 2.361. When touching other wires on the TCI plug I still get 2.361 readings.
 
orange wire when checking to see if shorted to ground has a reading of 2.363.

gray wire is for the front cyl coil (one not getting spark ) has good continuity with a reading of 2.361. When touching other wires on the TCI plug I get .OL

gray wire when checking to see if shorted to ground initially gave reading of 2.363 but now only gives .OL

[rayillu]

I did cut open the harness where suggested tonight and found the splice that was written about. It looked like it was previously cut open.  The only thing there are no loose wires.  The red and white wires are there spliced together but with a brass ring crimped around them and the ends of the wires sticking out.  There is another join like that and then another join like that with green wires only they are sodered.  All the joins were covered with electrical tape.  They were not the neatest joins I have seen.

Is this the factory wiring?  Even though the joins are solid could this be causing my running on one cylinder problem ( ...no spark coming from the front cylinder coil ) ?

What are your thoughts? Thanks.

Ray

[bstig60]

Ray,
What scale do you have your meter set on? The reading you are getting on the Gray wire, is this and OL or 01? Depending on the scale you have the meter set on, and assuming it is not 0000 or 0001, it indicates an open circuit. I assume you are taking these readings with everything unplugged....... The wiring harness is probably factory....... They did some wierd things. I would suggest soldering all the connections and using shrink tube on them, then tape over that to make sure you have good connections and nothing will get shorted to the frame in the future.

Bill

[rayillu]

It is a digital meter and I have it set on the ohm symbol.

The value I am getting on the gray wire is .OL

Everything was unplugged when I tested it.

It's obvious that I am not an electrical person so I guess an open circuit is not good?

[ViolinARC]

It appears the gray wire may be your culprit.  Get some good wire and try bypassing the gray wire at it's starting and ending point then recheck for continuity.  Hopefully, you will be getting the proper reading with the new wiring...GL again!

[rayillu]

thx very much. Much appreciated.

[rayillu]

Hey, thks again.  Thought I would follow up on my solution.  Ended up being a bad TCI.  Got the contact information for the guy in Illinois who rebuilds them and sent mine out.  Once I got it back from him and installed it....... bingo.  Runs UNBELIEVEABLE.  The best ever.

Ray

[rayillu]

Hey, thks again.  Thought I would follow up on my solution.  Ended up being a bad TCI.  Got the contact information for the guy in Illinois who rebuilds them and sent mine out.  Once I got it back from him and installed it....... bingo.  Runs UNBELIEVEABLE.  The best ever.

Ray