Thunderace electrical gremlin

wonkiwheel · Post by **wonkiwheel** » Thu Apr 14, 2016 8:00 pm

Engine rpm dips by 150 when i turn the main beam on, is this normal? my previous ace didnt do this. Bought the bike a few years ago with it doing this but didnt affect performance (even tho engine was shot anyway). So late 2014 changed engines and more recently added a manual override fan switch, all was well. Last week though i got brand new coils and changed the plug caps as the old ones were like 18k ohms, now if i have headlights on and fan on it slowly dies on tick over.
Tested the battery, fine with no load 14.75 volts on tick over
Put main beam on drops 14.1
Put fan on overcharges to 15.4
Put main beam + fan drops to 13.5
Run fine with both on at higher rpm.
Simple grounding issue or something more sinister? All but count out rec/reg and stator as the engine dip was there with previous engine.
Please go easy with wiring colours as im colourblind unless its black or white!!!!!

wonkiwheel · Post by **wonkiwheel** » Fri Apr 15, 2016 11:04 am

Found that the previous owner had added a bypass wire from the alt/gen connector (red wire) directly to the pos terminal in the starter relay that sends charge back to the battery, would this cause a bad ground as it isn't going through the relay box?

oldskoolexup · Post by **oldskoolexup** » Fri Apr 15, 2016 11:45 am

Can u post photo and if possible show on wiring diagram?

wonkiwheel · Post by **wonkiwheel** » Fri Apr 15, 2016 11:47 am

Yea have photos will upload later. Cheers

wonkiwheel · Post by **wonkiwheel** » Fri Apr 15, 2016 4:40 pm

additional wire yellow tape. wiring diagram #2 alt/gen. #5 starter relay im guessing. Even using just indicators or brake light blinks or fades the neutral light.

wonkiwheel · Post by **wonkiwheel** » Fri Apr 15, 2016 4:44 pm

yo4hgx · Post by **yo4hgx** » Sun Apr 17, 2016 4:50 pm

I can't see the pictures but based on information you provided, the lead from the voltage regulator (red) and the battery pos terminal is actually a main fuse bypass and I can't see why somebody would do something like this unless the fuse is getting blown. That would be the first issue I would check, remove the bypass and see what happens.

The reason for a leak to the ground could be a bad insulation somewhere within the wiring, connectors or even the voltage rectifier/regulator. To find it out you should split the circuit until find the area with problems. I should start by disconnecting the voltage regulator (charger) and run it only on battery.

Hope this make any sense to you...

oldskoolexup · Post by **oldskoolexup** » Sun Apr 17, 2016 6:46 pm

Ditto what y04hgx has suggested.......

I too can't see any other reason for the introduction of a "bypass" unless there is a fault elsewhere and this is a way of avoiding it.

Ideally, you should remove bypass and monitor what is happening but realistically you may have to disconnect and check all cables to see where problem lies.

Question. Is there evidence of any previous cable mods...e.g. an alarm fitment that has been reversed etc????

Where are you based?

wonkiwheel · Post by **wonkiwheel** » Sun Apr 17, 2016 10:40 pm

I disconnected the bypass and just ran on the battery, instantly noticed a difference, no dip in rpm with lights fan and indicators on, however no charge going back to the battery, I even changed the starter relay as I thought this may have been the problem as the red wire from the gen goes to it, but no change, no fuses blown, this red wire according to the circuit diagram links into a red wire that comes/goes to the ignition, is it possible that particular wire is fried (cant see signs of this), also no signs of alarm. Cheers

wonkiwheel · Post by **wonkiwheel** » Sun Apr 17, 2016 10:57 pm

Btw in even sunnier Wigan!!

oldskoolexup · Post by **oldskoolexup** » Sun Apr 17, 2016 11:25 pm

Are you saying that with the bypass disconnected there is no charge going from generator to red battery terminal?

It's possible there's a fried or damaged cable but you'll need to confirm if there is continuity between points in the loom where there should be a connection to verify and will need to be sure you have isolated cables to test adequately.

You should also check that points in the cable loom are properly isolated from the chassis, where they should be, i.e. there are no short circuits to what is essentially the negative side of the battery.

Have you got a multimeter or ohmmeter or access to one so you can test for continuity?

The other things to look for are poor connections on the various plugs etc.

Please bear in mind I don't know the cabling on the Ace so I might be just stabbing in the dark but I think you need to confirm that what should be connected is and what shouldn't be isn't and work through systematically.

I can't think of any reason other than a disconnect elsewhere that would prompt the previous owner to have added the bypass......Ideas anyone??

yo4hgx · Post by **yo4hgx** » Mon Apr 18, 2016 9:52 am

For some reason now I've been able to see the pics and it confirm what I suspected in the first place, the extra cable it is actually a generator-main fuse bypass. I can't think why one would do something like this unless a broken wire but however, the connection is on the "wrong" side of the fuse.

The wire thing has to be sorted out before moving forward but as long the engine runs well on battery only, the generator seems to need a check.

Suppose you have the service manual and a decent multimeter, on page 8-27 is described how to check the AC (3 phases) stator coils continuity (0.19-0.21 ohms) and rotor coil continuity (2.76-3.05 ohms). Insulation should be also checked but with regular multimeter could be tricky, for an accurate measurement a megohmeter should be a better choice.

As I said, things have to be sorted out one step at the time and check the circuit by breaking it into loops... but I have the sensation that one AC stator coils is either broken or shorted or leaking to the ground.

I'm in L-pool and if you need an extra hand for tests I could pass by one of the afternoons, just let me know.

wonkiwheel · Post by **wonkiwheel** » Mon Apr 18, 2016 11:25 am

Thank you. I managed to eliminate the bypass wire the red wire from the gen was broken in the loom, however, some of the same problem exists, it is now charging but rpm still dips by 150 rpm (maybe normal somehow doubt it though) I get 14.75 v with lights on but then when the fan kicks in it drops to 12.8 v and slowly decreases to 12.4 and eventually cuts the motor, so a leak of some kind is present. The override fan switch I fitted may be the problem but again I doubt it as I have isolated this and still get rpm dip and everything works fine on battery alone. Could it be possible my battery although tests good is just not holding amperage under load? This again would be odd as everything is fine when running on battery alone.

wonkiwheel · Post by **wonkiwheel** » Mon Apr 18, 2016 11:36 am

Again even though the rpm dip has always been present, the cut out has only occured since fitting the new coils. Old coils measured 1.9v 2.0v on the primary as opposed to 2.6v for the new ones. I'm guessing this 1.3v extra juice is causing the cut out but not the cause of the leak.

oldskoolexup · Post by **oldskoolexup** » Mon Apr 18, 2016 11:42 am

Do you know how old the battery is?
Suggest you have it tested under load in any event, to eliminate.

Have you actually found a break in wiring? If so, there may be another/others, necessitating continuity checks.

How have you overridden fan?