Mosfet regulator blows main fuse

[vintagemilano]

This will be a bit of a long winded post for what is essentially a basic question. I upgraded my rectifier/regulator to a mosfet one in hopes my cdi lasts longer. Used an FH012AA with eastern beaver wiring kits. Mounting was tricky but got it in the original location on the original bracket. Wired up great and rock steady 14.3v. Two drives later my 400 has blown it's 25a main fuse in the fuse block, I nurse it home as I was just down in town. Couldn't really find anything wrong, traced all my wiring, regulator, to battery, to fuse block, connections, all in between, put a new fuse in and put it all back together. Next drive, on the way home from work, blows the main fuse again about 10 minutes in. During a spirited left turn, identical to the first time but I'm thinking that's coincidence.... More bike dismantling, trace all main power wires from battery to ignition switch, bending, wiggling with a running bike to see if the fuse will blow. No luck. I've double checked this afternoon that yes indeed the fh012aa is correctly wired in. You can't muck up the three yellow wires, any order works for them. So now what? I feel like it's likely something I changed/touched as that's usually the way of things (I fix helicopters for a living) but my confidence is pretty good right now for the all of two wires I cut and spliced. Thoughts?
Bike only has 6000kms and I haven't run across corroded connectors anywhere else yet.

Thanks, 

[greg737]

So now what? I feel like it's likely something I changed/touched as that's usually the way of things

Yes, something has changed, and I'm voting for something in the OEM wiring harness got "twisted" or got "stretched" or maybe even both at the same time.  Now you've got an (occasional) path-to-ground, probably into the bike's frame or maybe from a "hot" wire into a neighboring ground wire, that probably shoots right past 25 amps (or would if the fuse didn't give up its life to save the situation).

Probably best to look very carefully at where you had to re-arrange (stretch/twist) the OEM wiring harness to accommodate the new R/R, the problem is most likely in that area.

Good luck with it.

P.S., Is B.C. on fire like almost the entire state of Washington?  Worst fire season we've ever had, like living in Beijing China.

[vintagemilano]

See if the attached picture goes through. I mounted the FH012 with the connectors down, even though I was worried about chain oil all over everything over time. Turns out there is enough chain growth at speed to get it to move up that almost 3/4" (19mm) and contact the black connector. Proves me wrong, I thought I was close enough to the front sprocket for that not to be a concern.

[Gouraami]

At least you found the problem, should be an easy fix