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Author Topic: MT250 Budget Build  (Read 6088 times)

Offline Sonreir

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Re: MT250 Budget Build
« Reply #60 on: Apr 21, 2017, 15:55:45 »
We have a couple of options with this setup.

Like the XL and XR, this bike uses both AC and DC circuits. The white/yellow wire running to the front of the bike runs the headlight on AC power directly from the alternator. The ignition coil has a dedicated AC coil coming from the alternator, and everything else is getting power from the pink and yellow wires that are run though the rectifier and to the battery.

I'd leave the ignition coil alone and keep it on its own circuit.

Next step is to replace all of the bulbs and the battery with 12V versions. You should probably replace the horn as well, but if you're feeling lazy you might get a few uses out of it before it pops. :P

Here's where the options come in.

The easier option would be to replace the existing rectifier with a combined 12V R/R,ensure all your bulbs are LEDs, and then wire the headlight to run from the brown/white wire instead of the blue/white. You should get the total wattage draw low enough to make this work, but a voltmeter might be a good idea until you're sure you're not going to kill the battery.

If you want to get the full charging out of your system and still do a 12V DC conversion, you're going to need to pop open the alternator and float the ground on the white/yellow coil. You'll need a second R/R to make this work, but you shouldn't have any power issues.

And another option is to try an LED headlight bulb on the AC circuit along with a 12V AC regulator. The bulb will probably flash a bit (especially at low RPM) since LEDs only allow current to flow in one direction, but you might be able to avoid tinkering with the alternator if the power output from option one isn't cutting it.

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Offline JSJamboree

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Re: MT250 Budget Build
« Reply #61 on: Apr 21, 2017, 16:05:31 »
The easier option would be to replace the existing rectifier with a combined 12V R/R,ensure all your bulbs are LEDs, and then wire the headlight to run from the brown/white wire instead of the blue/white. You should get the total wattage draw low enough to make this work, but a voltmeter might be a good idea until you're sure you're not going to kill the battery.

In this method we are basically running everything on the single circuit? Just make everything LED and hope it drops enough to keep the bike charged?

If you want to get the full charging out of your system and still do a 12V DC conversion, you're going to need to pop open the alternator and float the ground on the white/yellow coil. You'll need a second R/R to make this work, but you shouldn't have any power issues.

So with this guy we are basically taking two independant circuits with two 12v reg/recs.  figuring out how to unground the current W/Y and using the ground back up to the second Reg/Reg.  Then running the powers out of both reg/recs to the battery?  Would it not work to simply run the two in circuit?  So hooking the floating ground to the reg/rec, the W/Y and the P together (creating the series), then Y to Y like always?

After she is up and running and I know everything works I will likely give this a shot.

Offline Sonreir

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Re: MT250 Budget Build
« Reply #62 on: Apr 21, 2017, 17:27:17 »
In this method we are basically running everything on the single circuit? Just make everything LED and hope it drops enough to keep the bike charged?

Yup.

So with this guy we are basically taking two independant circuits with two 12v reg/recs.  figuring out how to unground the current W/Y and using the ground back up to the second Reg/Reg.  Then running the powers out of both reg/recs to the battery?  Would it not work to simply run the two in circuit?  So hooking the floating ground to the reg/rec, the W/Y and the P together (creating the series), then Y to Y like always?

After she is up and running and I know everything works I will likely give this a shot.

It's possible this would work, but it might not. The problem with running the two different coils together is that if they're out of phase, the power from one might cancel out the power from the other. You can try it (it won't hurt anything), but you might be worse off than just using the first option.
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Offline JSJamboree

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Re: MT250 Budget Build
« Reply #63 on: Apr 24, 2017, 10:52:47 »
So over the weekend I got to try and fire it, I got it to fire once after a bunch of kicks but never again.  When I pull a plug so that I can kick it over by hand and watch the plug I notice that it takes about 5-10 full kicks (which is about 10-20 revolutions) before the plug starts to have any spark.  After that it seems to keep sparking pretty good.  After it sits for about 20 seconds or so no more spark (I would assume thats expected as the condenser drains).  Being there is no battery is that expected?  I would think that it should only take about 2.  The RD starts up first kick without a battery but its got a fancy ignition.  If thats not expected does it sound more like a condenser/coil issue or a stator issue?

Offline advCo

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Re: MT250 Budget Build
« Reply #64 on: Apr 24, 2017, 11:32:17 »
Sounds like stator possibly, the XL sparks every rotation, every time. The condenser is probably shot, as the stock Honda ones were known to fail.


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Offline Maritime

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Re: MT250 Budget Build
« Reply #65 on: Apr 24, 2017, 11:35:50 »
My money is on the condensor not building park well then not holding juice long enough to get it to spark reliably. Condensors are usually cheap to swap, but also make sure you have a really good ground on it. I know on the GL I added a ground strap to the condensor as a bad ground would really effect the spark quality and they ground to the frame and that spot rusts etc so a wire straight to the frame ground from the neg battery terminal makes sure the ground is the best it can be.
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Offline JSJamboree

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Re: MT250 Budget Build
« Reply #66 on: Apr 24, 2017, 12:18:46 »
Sounds like stator possibly, the XL sparks every rotation, every time. The condenser is probably shot, as the stock Honda ones were known to fail.


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Im REALLY Hoping its not the stator as thats not a cheap part on these motors.  It sounds like from what Spark said we have the same setup so if yours fires even first rotation then im assuming mine should to.  I'll buy a new consensor just in case, did you find a place to get them cheap?  This is good information thanks,

Side note, is a condenser a condenser? is there a difference in 6v vs 12v, amperage etc? Or can I really just get any condenser out there and swap on there?

My money is on the condensor not building park well then not holding juice long enough to get it to spark reliably. Condensors are usually cheap to swap, but also make sure you have a really good ground on it. I know on the GL I added a ground strap to the condensor as a bad ground would really effect the spark quality and they ground to the frame and that spot rusts etc so a wire straight to the frame ground from the neg battery terminal makes sure the ground is the best it can be.

I'll give that a try too.

Offline farmer92

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MT250 Budget Build
« Reply #67 on: Apr 24, 2017, 12:25:20 »

Side note, is a condenser a condenser? is there a difference in 6v vs 12v, amperage etc? Or can I really just get any condenser out there and swap on there?

I'll give that a try too.

The condenser is a capcitor,
Ideally you get one with the same farads as original.

6v 12v is irrelevant, but the capacitor will be more charged at 12v than 6v. So the voltage will dictate how many microfarads the capacitor would be.

To few and the capacitor could fail.
To many and it won't have be able to recharge the coils effectively

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« Last Edit: Apr 24, 2017, 12:33:53 by farmer92 »

Offline advCo

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Re: MT250 Budget Build
« Reply #68 on: Apr 24, 2017, 12:40:12 »
The unit I bought came from eBay, relatively inexpensive.

If you're converting to 12v, the ignition will still run directly from the stator at 6v, so you should be fine replacing it with an OEM equivalent.
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Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
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Re: MT250 Budget Build
« Reply #69 on: Apr 24, 2017, 12:51:45 »
The unit I bought came from eBay, relatively inexpensive.

If you're converting to 12v, the ignition will still run directly from the stator at 6v, so you should be fine replacing it with an OEM equivalent.

When i look up MT250 condenser on ebay, they are like $30.  You can get generic ones for like $10, so I was hoping to just nab one for like a cb550 and change the plug.