90' XR250R charging issues.

Ok after a few days of searching the forums for something similar to what i'm looking for or results found from a similar set up, I found some helpful but can't seem to get it cracked down to find the problem.....

I plan on doing this: Converting the bike to street legal. I have found out that yes the original system is AC so what I have done is exactly this -> I bought a couple Full bridge rectifiers, 1000V, 50A. A bit overkill but whatever at least they can take some abuse.

I have the whole electrical system done and wired, all new 16ga. wire. Regardless of how I have my whole system wired and found the same gay ol results so I broke down and bypassed all outside junk I do not need (lights, switches, etc.) Just the regulator and rectifier.

What I have hooked up is:

Alternator, (Pink and Yellow wires) to the AC Regulator (Stock XR one), from the AC Regulator I have the (Geen and White) wires going to ONE Full Bridge Rectifier, (Green and White) going to both AC connections on the rectifier.

Fire the bike up, and at idle I get at the (+ and -)DC side of the rectifier 11.9VDC MAX (w/o a 12V battery). Revving engine the voltage goes down.

Working backwards now, using the multimeter set on AC remove the connectors for the Rectifier, multimeter leads right at (Green and White) off the regulator. 11.9VAC MAX. Again revving engine voltage drops.

I tried something else here, I connected the (Green and White) bullet connectors from the AC Reg. back to the stock harness. I used the Mult/M set on AC, I connected the tail light wires, (blue and green) to the leads. What did I find, a whopping 13+ AC volts when revving it up.

I worked my way down right to the Alternator connections, I get from idle 19VAC all the way up to around full throttle 115V AC.

I've messed around with this bastard pretty long and its slowly getting the best of me. I have also tried having the system hooked up with a 12V battery also, but it starts out at its charged state 12.6VDC and drops down to the 11.9VDC region as things use up the energy.

I might try to hook the Rect. to the taillight connections (blue and green) that were getting 13+ VAC and see what happens then. I'm running out of ideas.

It's the stock stator, I did the resistance check on it and it checks out with the Clymers manual I bought recently.

Any help or ideas really appreciated. Thanks

Ok I did some more messing around tonight and still the same ol story. Other then i'll update the one note on the original post here.

The 13VAC I was seeing, well I tried that same set up tonight and I could not get it, I don't know if then it was a freak occasion when it worked but who knows, I can't get that anymore.

New things I tried tonight:

Hooked the Rectifier straight up to the alternator plugs, (pink and yellow) and at idle off the DC side of the Rect. I get 13 - 14 VDC as you rev it up of course the volts went up because I had no regulator hooked up. So I did just that and the results were the same old 11.9VDC MAX at idle and as the speed goes up the volts go DOWNNNNN to hell.

All I can think of is that the Regulator is toast or maybe the stock regulator was only designed to put out just 12volts at the very most...

Anyways I might check into a regulator I'm sure I found one in the motovan or parts canada catalogs, for pretty cheap. Then again I might just be wasting money because it turns out that I cannot license this pig in Saskatchewan. I do want to get things figured out though so I can at least have lights on it and stuff on the trails.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now