Bought a 94 XR250R in boxes... Rebuild thread

[jamesm113]

Well, just like the title says, I bought a 94 XR250R in boxes.  The previous owner took the engine out, had a shop replace the headgasket, and gave up putting it back together.  I know very little about it.  To be honest, I know very little about XR's and dual sports...

 

Here's what the owner has told me:

1. It's CA-plated with some baja kit

2. It's been bored out 280cc, but requires 87 octane

3. It has a battery but it's been disconnected because the bike runs OK off the stator only

 

Here's what I've figured out.

1.  You can't pull the spark plug without a special tool from honda.     

2.  Compression was between 125PSI and 150PSI with the engine stone cold.  

3.  A leakdown test yields 15-20% pressure loss through the rings.  I guess not too shabby for a 22 year old dirt bike.

4.  Jetting is a JS7B-3 needle, 128 main jet, 42 pilot, and 4+ turns out.  This seems off to me, but it's low on my list of things to fix.

5.  Exhaust valves are between .10 and .13mm.  Spec is .08mm.  Intake valves are between .04 and .05mm.  Spec is .05mm.  I'll adjust those later, but again, that's pretty low on my list of things to fix.

6.  The wiring, which is a mix of OEM parts & random dual sport kit parts is going to be a major headache   

 

So first order of business was to finish installing & torquing the engine & extra parts - kick starter, levers, pedals, etc.  That's all done.

 

After that, I pieced together the essential wiring - the alternator, coil, regulator, ignition control module, etc.  Had to solder the pulse generator wires back together because the previous owner cut them instead of removing the connector.  ?   I then hooked up the tail light and kicked her over and got the brake light to shine dimly as a test..  Progress!

 

Figured I'd say screw it and hook up the gas tank.  After a few kicks and some tinkering with the petcock and choke, she started up and purred at a steady idle.  More progress!

 

 

Now I need help figuring out the proper wiring & routing for the wiring and the dual sport kit.  The 86-95 service manual isn't very descriptive and most of the components/wires are from some ancient dual sport kit anyway.  So 3 questions to start

 

1st question - the regulator.  Anyone know what it's from?  It looks like nothing like pictures of the Honda 31410-KZ1-670 on ebay.  I used my multimeter to confirm black is ground and used the wire gauge to guess red is the output & the smaller gauge yellow wires are the AC inputs from the stator.  Is it DC or AC?  Where the heck is the regulator supposed to be mounted?

 

2nd question - What's the proper positioning for the rear pigtail & grounding point?  I took my best guess here.  Sorry for the blurry picture.

 

3rd question - How does the battery hook up?  Assuming the regulator is DC, I would just tie it into the main regulator output, correct?  What's the benefit of using the battery?

 

4th question - those stupid pigtails - is there a better way to hook up to be hooking up these wires?  I feel like some vibrations will pull them apart easily

 

Service manual electrical diagrams:

 

Edited October 20, 2016 by jamesm113

[Undercover Poe]

I run tusk dual sport kits on both my xr400 and 85 xr350 but they probably work the same. My battery runs the led tail/brake and turn sigs,as,well,as beeps the horn. Very few parts of the tusk kit interface with the bikes wiring. Only the feed to the headlight really. That hits the handle bar control and it's used to switch from hi to low beam, should I have that type of headlight. (which I don't, I just run the stock XR headlights). I have stand alone brake switches one banjo style in the front hydraulics and one very simple old school switch that mechanically activate the brake light (that's the 85, the 01 has two banjo bolts switches for brakes). And it's as simple as that, no other interface with the bike. If i was smart I'd covert the stock wiring to dc and change my battery, but I'm not so I just charge the battery every couple weeks/month or so. The good news is the bike purrs, the street legal kits are kind of not needed (at least where I live and the rides that I do) most riders that I ride with on turkey runs, etc don't even bother to do anything beyond a head light and tail light, I'm the only fool out there with turns and a folding mirror, but whatever, these things keep me busy.

[mikerbike]

There's no reason ever that you should ever run 87 octane in any motorcycle engine. 280 bore doesn't necessarily mean higher compression ratio, but it almost definitely doesn't mean lower compression ratio.

XR250R doesn't need a battery to run. All the lights in your dual sport kid shouldn't need a battery to run either. The Horn is the only part that actually needs DC power to operate.

Motion Pro makes an 18mm thin wall deep socket that fits. If you've already bought a Honda socket, disregard.

The 86-95 XR250R was not street legal, so none of the wiring in the FSM will help except the stator output colors, IMO.

Your regulator appears to be a rectifier as well. Same colors as the Trailtech unit without the relay circuit. Definitely not a factory XR regulator.

If you're going to run DC power, the location of the AC system ground doesn't matter, as all it will be used for is the kill button. Neither the factory rear pigtail because it doesn't incorporate a brake light.

Check this page for connecting he battery..

http://gallery.trailtech.net/media/instructions/lights/regrec/010-ELV-116.pdf

The two yellow inputs don't need to be connected any certain way to the bike's stator output wires.

The benefit of using a battery is that your horn will work and you can leave the lights on after the engine has shut off. That might be a requirement to get it street registered.

Those stupid pigtails are stupid, but they probably won't pop apart from just vibration. I have gone to the automotive junkyard and chopped plugs out of wiring harnesses for this sort of usage. You can find plugs with just aboot any number of pins. Then I just solder them in line. There's probably a less jimmy-rig supply of plugs, but as you've found, there's also a more jimmy-rig supply of plugs.

[jamesm113]

Thanks.  I called Baja Designs and they confirmed it was one of their old regulators.  But they said it was from the 90s and pretty much didn't want to touch it with a ten foot pole.  They didn't have any documentation and they recommended I get a new one too.

 

Any idea where the heck I can mount it?  I'm currently using zip-ties to mount it just above the engine mount, but I'm know once I go over a rock bigger than a pebble it's going to fall out.

[Undercover Poe]

Try and get it on the flat spot on top of your air box. That's were I keep all my DS "junk". Except I put the flasher relay behind the headlight.

[mikerbike]

Try and get it on the flat spot on top of your air box. That's were I keep all my DS "junk". Except I put the flasher relay behind the headlight.

I second that! My 94 250R held the regulator and Tusk battery right there. It's a lot smaller than your battery but it's literally only used so that the rectifier works. I used a capacitor do a while too. Lighter weight and smaller size. It stopped working after a while though.

[jamesm113]

Bike is up and running now!  Done a few rides around town so far. 

 

It turns out the area above the airbox is filled by the battery.  I got the regulator zip tied in above the frame.  The previous owner confirmed that's how it was before... sooo    I'd rather have something more secure, but this seems to work for now.  Maybe I could get rid of the battery to move the regulator above the airbox, but the headlight dims quite a bit when approaching stop signs when it's running on the stator.

 

One more mystery has sprung up.  How do I hook up the brake light switch? The previous owner doesn't seem to know/remember and every place I've tried didn't work.

 

I adjusted the valves to spec, and i think it's starting a bit easier now.

 

I also discovered the fuel screw o-ring and washer are missing, as well as the choke arm plate, so I have some more parts to order.

[mikerbike]

That battery is absolute overkill for what you're using it for. The Tusk 12V battery is 10 AA batteries in a pack so the reg and battery can both fit. Maybe try to find the OEM regulator rubber boot thingy?

[Undercover Poe]

Bike is up and running now! Done a few rides around town so far.

It turns out the area above the airbox is filled by the battery. I got the regulator zip tied in above the frame. The previous owner confirmed that's how it was before... sooo I'd rather have something more secure, but this seems to work for now. Maybe I could get rid of the battery to move the regulator above the airbox, but the headlight dims quite a bit when approaching stop signs when it's running on the stator.

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One more mystery has sprung up. How do I hook up the brake light switch? The previous owner doesn't seem to know/remember and every place I've tried didn't work.

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I adjusted the valves to spec, and i think it's starting a bit easier now.

I also discovered the fuel screw o-ring and washer are missing, as well as the choke arm plate, so I have some more parts to order.

in the attached post I describe and document the rear brake light switch on my 85 xr

Dual sporting my 85 XR350r

https://www.thumpertalk.com/index.php?/topic/1171597-Dual-sporting-my-85-XR350r

[jamesm113]

Thanks for the pictures, Undercover Poe, but our bikes are just different enough that it's not a match.  My brake lever is inside the frame the decompression cam gets in the way or the brake light switch blocks the kickstarter.

 

I gave up on trying to make the brake light switch fit and found a banjo bolt (M10x1.25) switch off ebay for under $6.  So I got one of those and hooked it up.  Seems to be working good so far.

 

However, now my headlights dim 70% whenever I brake  ? ?     Very fun when I'm riding at night on a dark twisty road...  Oh yea, and my turn signals cause my headlight to dim too.  I'm guessing the stator doesn't have enough power to run everything.

 

I'm gonna try LED lights, but I have a feeling I'll be trying to get the supersonic battery working or ordering that tusk battery soon...  In order to get the battery working, I'll need to wire the low/high beam switch to the tail light.  Any ideas on how I can accomplish that?  i believe the high/low wires are simply connected to grounded when turned on...  If I wire the tail light to 12V in the rear, and run a signal/ground wire to the front and splice it in to both the high/low wires.  if the light switch is off, the tail light won't be grounded, otherwise, either the high or low beam line will be grounded.  But then the low beam / high beam would be grounded at the same time.  Maybe I need a diode??

 

I do have to say, it's quite a fun bike to ride around town   

Edited October 28, 2016 by jamesm113

[Undercover Poe]

If your add ons are dimming your head and tail to the extent that it is noticeable and affecting your ride, I'd divorce them and run the add ons off the battery if you can afford to charge your battery every so often. That the way both my xrs are set up, the add on are stand alone. Plus I think it's better for the xr to run only the lights as Honda intended, unless you upgrade the stator. but what do I know?

Edited October 28, 2016 by Undercover Poe

[jamesm113]

I realized I never posted pictures of it.  So here's two pictures from my first dual sport ride with it yesterday.  It was an absolute blast on the twisties and it handled off-road duties well, even though the tires are completely bald     ?   Only scary moment is when it stalled after a deep water crossing and wouldn't immediately start back up again.  I gave it a few minutes (mostly to give myself a breather  ) and it kicked right over.

 

The brake light dims the headlight to the point where it's next to useless, so it's definitely something that needs to be addressed.  

 

The lights off the battery sounds intriguing.  How long would the battery last between charges?  I also have burnt out 4 tail light bulbs in 2 weeks... think that's from the stator/regulator not being smoothed out by a battery?

 

I was also looking into rewinding the stator.  To my untrained eye, the stock wiring looked like it was 18 gauge... can anyone confirm that?  Would it be worthwhile to use 16 gauge wire?  How many total feet would I need?

 

Also, another unrelated question - do you need to bleed the shock reservoir if it was disconnected?  The previous owner gave me the shock reservoir in a box and i just bolted it on, but the suspension did feel a little wallowy in the dirt to me. 

[jamesm113]

Well, I kinda just went ahead and pulled the stator.  There are 8 total coils - 4 are used for lighting, 2 are used for ignition and 2 are unused.  The wiring is 20 AWG magnet wire.  I counted 78 turns per coil, and roughly 18-20 feet of wire per coil, for a total of 312 turns and 72-80 feet of wire.

 

Reviewing the awesome Stators Demystified thread over at AdvRider, I've ordered thicker 18 AWG magnet wire, and plan to spread the 312 turns (or actually, slightly less) over all 6 coils.  Doing this should provide for a 50% increase of current & a 50% reduction in resistance with the same voltage.

 

Underwinding slightly will provide more current & less resistance with a little bit of a reduction in voltage below ~1500RPM.  I think that's a good trade off, since even at idle, the current will be increased 50% before the stator was rewound.  So roughly 290 turns over 6 coils...