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Fishfearhim2

XV535 Electrics/smoking CDI unit

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Hi, I've just bought a 1994 XV 535 Virago. The bike has sat used for 5 years in a garage. I collected it on Sunday when the seller proudly announced that he had managed to get the bike running. He had put some fresh petrol in the tank and jump started it using the battery on his car (not sure that's good thing to do?). He said that the bike was running for over 20 minutes as he trying to get some charge back into the bike battery. When I arrived the bike battery was totally flat, so the seller connected jump leads to his car again and with full choke the bike started. I seem to remember being told it's bad to run a motor with a battery of much higher amperage connected, so I disconnected one of the jump and the bike immediately cut. Upon re-connecting the jump lead each time the ingnition switch was turned on it immediately blew the 15 Amp ignition fuse, a few more attempts were made until we ran out of 15 Amp fuses. When I got the bike I removed the battery and tried to charge it overnight to no avail, it's had it. To try and start the bike today I connected an old bandit battery that I had, but it wasn't fully charged so the engine would turn over. The indicators worked but not much else. It was then that I noticed smoke coming from the plastic chrome RHS cover. Under that cover are a few relays an an odd looking thing in a small sealed see through plastic bag? (what is it?) and the CDI unit which still had smoke coming from it? I turned off the ignition and removed the battery. The 15 Amp ignition fuse hadn't blown, but perhaps this is due to the weak battery?

1. Is the CDI unit now toast (was it fried by the car battery yesterday?)

2. Has the rectifier been fried by the car battery, thus allowing to much power to the CDI hence causing it to overheat and smoke?

3. Have both been fried?

4. Can a rectifier and CDI be checked without specialist equipment.

A new and correct battery is now on order, but I fear by connecting I'll fry the CDI even more?

Any help, suggestions or similar problems with what you did to solve will be gratefully received.

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Firstly its the car and not the bike that could be damaged due to the jump starting. The ECU could receive a voltage spike that can damage it - done it myself and had to have the ECU repaired which was very expensive. Lesson learnt don't jump start modern cars (or a bike from the car).

If the cdi is smoking its not likely to be caused by being jump started - there must have been a fault there already.

I know these CDi units do burn out as we just repaired one for the XV100, the diodes get extremely hot when they fail.

You can test the regulator/rectifier with a multimeter. The CDi you need specailist equipment (which we have).

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Thanks for your reply. Is the CDI unit repairable? In your experience, once the CDI is repaired or replaced do you think it'll overheat again? e.g. is there something else causing this problem? Thanks again.

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If you are sure that smoke came from the ignitor (CDI), then it is officially a paperweight. It is not repairable. Don't be concerned about frying the unit even more-once it's done, it's well and truly done. If you are not sure the ignitor was smoking (You have a question mark at the end of that sentence.) examine the ignitor for blacked areas and/cracks.

No cracks or other visible damage? Test for spark by connectiing one of the sparkplug wires to a grounded sparkplug (ie: with a jumper wire end either on the threaded portion or the ground electrode, other end to engine..) then crank the bike while observing for spark. A shady/indoors location makes spark more easily visible .It's important to ground the plug with a jumper wire, otherwise the ignitor can be damaged by this test.

While the was bike running, did you at anytime NOT have a battery connected? That could damage the rectifier or regulator unit.

So once you have a fully charged replacement battery** installed (and likely you need a ignitor too, ouch!) start the bike and measure the voltage at the battery terminals. You should see about 14.5 volts. Less than 14.0 -the regulator or rectifier is defective. More than 14.9- the regulator is faulty and will eventually damage your battery..

** should measure 12.5-13.0 volts disconnected from the bike.

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Dear Berniebee, thanks very much for your reply. Are the regulator and rectifier together in the same sealed unit? I removed the plastic chrome cover on RHS (O/S) of the bike this revealed the CDI plus a relay, which I think is headlight, a flasher unit, a small unit that's possibly a ballast resistor or capacitor and something that looks like a one pound coin connected to 2 wires which is incased in a thick sealed see throught plastic wallet - any idea what this is? A friend suggested it might be a solenoid ? With all these bits now exposed I turned on the ignition switch again, and within a minute smoke starting to come from the CDI unit with the smell of burning circuit board lacquer....not good! I'll get another CDI unit.

I don't know for sure if the bike was run with a battery not connected? I'm fairly sure it wasn't and when I initially saw the bike it started and ran for a few moments whilst being jumped off a car battery, before it started to blow fuses. We did disconnect the bike battery and connect the bike directly to jump leads attached to his car, but again the ignition fuse blew immediately the ingition switch was turned on.

I've had the original battery on charge now for 24 hours, using my optimate charger, which indicates the battery is weak, so I'll get a new one. I've never had much luck with flat batteries. Once they die that seems to be it?

I'm now hoping that when I fit the new battery and CDI, that there isn't a fault somewhere that results in the new CDI being fried again ??

Thanks again ... any idea what the pound coin thingy is ?

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Rule of thumb with ignition units, if they are potted in resin they are virtually impossible to repair. While we have chemicals here at the speed shop that strips the resin off in an hour, they also damage insulation.

If the box is not potted it can be opened. If its smoking it a fault on the power side. Providing the board has not been badly burnt and the microprocessor not damaged they can be repaired.

If the the unit is easily available a replacement would be the way to go, if not a repair would be worth paying for.

One point to note, more often then not owners taking the box apart to have a look themselves turn a repairable item in to scrap. There are components in there that will fail if subjected to the static charge that builds up on your clothes.

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