Yam XJ 600 Diversion coils and cdi blowing

[Guest]

So. bike had been standing waiting for me to fix it for the MOT. Did the work, jump started the bike to find it was on 2 pots, 1 and 4. Coil for 2 and 3 was kaput along with that side of the CDI ... confirmed by cross connecting. Left it another couple of months then got back on it. Coil and CDI from Ebay, all running good. Mile into the run to the MOT it goes on 2 again, exactly the same fault. Bad coil is short circuit on the LT side and open circuit on the HT side. I'm thinking either i have an intermittent short in the loom between the coil and CDI or really bad luck!! Replacement parts ordered from breaker. This happened to anyone else? ATM I'm looking at fitting another £35 worth of bits and hoping it don't happen again. May replace the CDI to coil wire just in case.

[eastanglianbiker]

I would also be checking the pick ups on the end of the crank for shorts or to much play in the plate causing a short

[Guest]

Right. I disregarded the pickups as I thought they would affect both sides not just 2 and 3 but will do that in case, thanks for the input!

[eastanglianbiker]

You have a pick up for each coil hence there being 2on the plate but for it to happen once hot make sure earths are good as well

[Guest]

Ok thanks. For some reason I thought there was just one. Maybe thinking of a different bike.

[Chrissb6]

So. bike had been standing waiting for me to fix it for the MOT. Did the work, jump started the bike to find it was on 2 pots, 1 and 4. Coil for 2 and 3 was kaput along with that side of the CDI ... confirmed by cross connecting. Left it another couple of months then got back on it. Coil and CDI from Ebay, all running good. Mile into the run to the MOT it goes on 2 again, exactly the same fault. Bad coil is short circuit on the LT side and open circuit on the HT side. I'm thinking either i have an intermittent short in the loom between the coil and CDI or really bad luck!! Replacement parts ordered from breaker. This happened to anyone else? ATM I'm looking at fitting another £35 worth of bits and hoping it don't happen again. May replace the CDI to coil wire just in case.

 

Question why did you have to jump start the bike? Was the bike battery disconnected, flat or u/s? If so, your voltage regulator will sense this and give out a very high voltage which could be the source of your problem. Make sure your charging circuit is giving out the correct voltage before you hook up anymore replacements. I doubt very much that the pick up is the cause of the problem.

[Guest]

Yeah battery was flat. Have checked voltage across it which went up to about 13.5v when revved which seems ok, but you may well be right about jump starting the bike. It had occurred to me, but I was half way to the mot station when it broke. Tachometer shooting up and down for a few seconds then bike on 2. I intend to charge the battery next time. Have jumped bikes and run them to charge countless times in the past with no ill effects tho

[Chrissb6]

Yeah battery was flat. Have checked voltage across it which went up to about 13.5v when revved which seems ok, but you may well be right about jump starting the bike. It had occurred to me, but I was half way to the mot station when it broke. Tachometer shooting up and down for a few seconds then bike on 2. I intend to charge the battery next time. Have jumped bikes and run them to charge countless times in the past with no ill effects tho

 

Hi Mate, seems like someone else has experience the same trouble so it could the regulator

http://yamahaclub.com/forums/topic/1186 ... diversion/

[Guest]

Checked across the battery like I said and it seemed fine..will recheck tho. Last thing I want is to fit the bits and have them go for a third time!!!!!