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Triumph keeps blowing fuses after tri spark install.

3997 Views 8 Replies 4 Participants Last post by  Tony the torch
I posted this on the britbike board too, figured maybe one of you could help.

Howdy all, I've got a 71 bonneville I installed a tri-spark classic twin ignition with their dual 6v coils, and their 3-phase alternator/voltage regulator kit. Spendy but the way I wanted to go.

I finally got around to putting this bike back together, and it ran fine before when it ran. So now I've got everything wired up the right way, double checked the diagrams they gave me for the new setup, and went through the static timing procedure. Verified TDC and 38 deg. before with the crankshaft notches, and also through the spark plug hole.

It started up on the first kick, and I didn't even have to kick it very hard, but the bike only ran for a few seconds before I blew a fuse(looks like the original Lucas fuse). The motor sounded great those two seconds as well. I'm thinking I have a short somewhere but I'm not sure how to go about finding it, electrics are not my specialty at all. I've got some new fuses, 15A and 20A, but don't want to try starting again until I'm pretty sure I won't damage the new ignition. I'm hoping the symptoms might be telling of a problem.

Here's some pictures of the wiring...The three alternator wires go to any of the three yellow wires of the voltage regulator, and the black and red wires from the voltage regulator go to their respective battery terminals, those are the extra wires on the terminals.

The jumper wire I have between the coils is brown and white, I just scavenged that from some spare wires I had. It's not connected to anything else. There's also a red wire connecting the white/black and yellow/black, again, just what I had on hand.

The only wires that aren't connected are two blue/brown wires with a single connector, a blue brown wire with a single connector, and two red wires with a single connector, hopefully you can see this.

As it is, it will run for maybe five seconds with a fuse in before it blows. I even took the seat off in case it was shorting out to the pan, and it did the same thing again. I have 15A and 20A fuses.

Any help would be greatly appreciated, I really want to ride this thing again before I have to put it away for winter.

And here's a link to the tri-spark website for their installation instructions and troubleshooting guide.


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disconnect the charging system wires (yellow) and see if the bike will run and not blow a fuse on the battery power only, I suspect it will,and that would make the suspicious fuse blowing part in the charging system.
the bike should have a 25 amp fuse in it too. I know it's scary when you have a $325 ignition in there, and be careful, the Trispark ignitions are kinda voltage sensitive.
Tony, I just unplugged the alternator wires. Started it up and you were right, it runs and doesn't blow fuses. And yeah, I'm trying to proceed with caution because I don't want to wreck the thing. So what does this mean for me now?
ok make sure you have the charge wires hooked up to the battery correctly, I know this sounds dumb but red is positive and back is negative... right?
then the thing to do is with the black and red wires disconnected from the wiring system, fire up the bike and measure the voltage on across those red and black wire. I should be 12.5 -14.5 VDC, if it's more that that then the regulator box is defective
Yep, red is +, black -. I'll have to check that tomorrow, pretty sure the neighbors will be calling the fuzz if I keep dicking around with the bike tonight. So I should plug the alt wires back into the regulator, disconnect the wires from the reg to the battery, and then measure the output voltage of the two wires while running?

And I can't seem to get the bike to idle below 2,000rpm, even after turning the amal's throttle screws out until they stopped moving the slide down. This will affect the reading I get from the regulator because I'm not reading at idle, right?
That idle's probably due to warped carb flanges I bet, I do have a pair of the JRC carbs I was meaning to put on anyway, I'll try that and check the amals just to make sure that's what's going on with the high idle.
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