Bonneville America Forums Forums Technical Forums General Tech Need help with electrical/ignition issue

Can't figure this one out...

Symptoms: one morning, bike wouldn't fire on the right cylinder. I checked and it was getting fuel, but zero spark. That night after work I went to work on it and still no spark. I changed the spark plug wires at the coils and there was now spark on the right wire, so it isn't the spark plug wire. I then changed the spark wires back and changed the wires going into the coils and there is spark, so it's not the coil.

I checked for loose connections throughout and cannot find any, and then suddenly it starts running again on it's own. I foolishly road it to work this past week and at lunch it's the same issue again, not firing on the right cylinder. That night I drive my car back to work to try and fix it and voila it's running before I've done anything but push the starter.

I've done a continuity check on yellow/black and yellow/blue wires running into the respective coils and found them fine. The red wires I cannot tell for sure with the poor diagram I have where they lead to to check them, but this doesn't feel like a wiring issue.

Any suggestions??

I hate to say it but it appears your CDI unit is starting to fail. It appears that you have checked the coils and wires by swapping things out. The only other thing that might cause the bike to run on one cylinder is the pickup coil gap being set too high. It should be .8mm but the early models were set to 1mm. Another thing to consider would be the wire running from the pickup coil. Pat mentioned earlier in another post that the wire has a connector under the seat. Single wire. Check the continuity there also.

Good luck.

wow, reading around it seems to be a common issue but one I've never heard of before. Is OEM the only way to go, or are there aftermarket CDI units that may be better and/or less expensive. any advice appreciated ...

thanks

That's pretty much how it went with me, running fine one day and on one cylinder the next. I bought a used OEM unit from Pinwall Cycles because there was no alternate igniter to try. ProComm now makes an aftermarket replacement (that unit has recieved mixed reviews). If you go for an OEM replacement be sure to check which motor it's for, igniters for the 790s are different from the 865s.

Wendy's lost 1 cyl in Niagara but the it came back and was fine all the way home even in the pouring rain. Mine quit twice in the rain, first time that ever happened to me and I have ridden in much heavier rain in the past many times. Wendy's quit in warm sunny weather but came back. I hear the procom has problems at low RPM and that bothers me since I may be in the market soon. So I am interested in alternatives too. My question is too those who have cut out in the rain, is that the beginning of the end of my CDI or are they OK once dry again?

Funny, in all my browsing I've never heard of this issue before, but when you look for it, there is a lot out there about it. I've got a Procom in the post due Monday, so hopefully that works.

oh, and thanks all for the advice. You're a great resource as always.

John,

Keep us posted on the outcome