MC54-250-B Died at speed on the highway!

[smoak]

So, I will try to boil this down simply for ya!
A couple of days ago I was riding at about 70mph on a backroad and my bike cut out for just a second, then gained back to speed no problem.

Well today I was on a 100+ round trip I was on my way back when the bike cut out and died. First it lost power, then caught back up and ran again, then died completely. I got it over to the side of the road and let it sit for a few minutes. After it sat for I bit I started it back up. It sputtered for a minute then ran fine.

About 30 miles down the road it just died alltogether. The motor would turn over fine, but would not crank up and run.

So, 1.5 hours later I get it off the truck and in the garage and I try to start it. It hits over and nearly starts.

So, I didn't have time to fool with it anymore tonight, so I let it sit and came in the house.

Here are my thoughts... When trying to crank it I was giving it gas at the throttle, and I never even smelled fuel like I was flooding it out.

So, I am thinking the fuel pump went out, but it might also be my distributor.(CDI I think it is called?)

Any thought on this?

Now, the bike has the horizontal yami clone motor, I just went through and checked/siliconed all my electrical connections in a pre season tear-down and PDI, so I don't think it is a loose connection.

thanks!

Smoak

[spandi]

Well if it is you might want to try one of these, as the Chinese OEM stuff has been known for conking out. (I put one in and no worries.)



http://www.amazon.com/Mikuni-Fuel-Ou...ound+fuel+pump

[richardthescooter1]

To get it started spray some carb cleaner in the air take or in the carb diaphragm, Are you climbing hills when it shuts off? Also might want to check all vacuum lines and intake to make sure they are tight.

[smoak]

Originally Posted by spandi

Well if it is you might want to try one of these, as the Chinese OEM stuff has been known for conking out. (I put one in and no worries.)



http://www.amazon.com/Mikuni-Fuel-Ou...ound+fuel+pump

Thanks, I was looking on ebay last might for the mikuni pumps.. I will check this one out as well!

To get it started spray some carb cleaner in the air take or in the carb diaphragm, Are you climbing hills when it shuts off? Also might want to check all vacuum lines and intake to make sure they are tight.

I will double check my vacuum lines once I get it tore down to bare frame.. Nope, wasn't putting it under much hill stress.. Just running about 55-60 on fairly even road..

I was also looking at CDI's last night.. I was seeing normal and "performance" both for my 250.. all a performance is really does is up my rev limitations, correct? So going performance would be pointless on a bike that doesn't redline until 80mph anyway?

I guess I need to check my coil as well.

First order of business will be to check for spark, and pull the fuel line and see if the pump is working...

thanks for the responses, guys!

[spandi]

You're quite welcome. (hope you find the "culprit" and are back on the road!)

[richardthescooter1]

Just yesterday coming home, scoot wasn't acting right, started to give it more gas and started to choke (Yep, that stupid intake clamp came loose)

[smoak]

So I had a chance to tear off the back half of my bike and really take a look at what was going on... So, things I found that seemed to be working:
1. I have spark
2. Gas is free-flowing from the filter
3. Fuel pump is working like it is supposed to

My carb, on the other hand, I could grab it and turn it sideways with little effort... So, I replaced the hose clamps on both sides of the carby and she cranked up... Maybe that was it, maybe not... I know now that it for sure isn't my fuel pump.... So I am still thinking I need to look into a new coil and CDI..

BTW, I think I found my CDI under the seat in the storage area, is that normal?

Now, for the real problem ATM. I let the bike sit and idle for a good 10 minutes to warm up and see if the CDI or coil would get hot enough to want to kick out... Well, I happen to glance at the wire harness cluster on the right rear and saw SMOKE! Yikes!

I isolated the hot wires to this particular set:

Photo Apr 29, 5 20 21 PM.jpg

See the messed up harness? It melted together.... The wires are going to a rubber plug in the top of the crankcase:

Photo Apr 29, 5 20 53 PM.jpg

It is just to the right of the bracket... Here is a wider shot to show where it is a little better:

Photo Apr 29, 5 21 03 PM.jpg

The only thing I can think of that is right there and need wires is MAYBE a low oil pressure sensor.... Any ideas what this is and why it melted the harness? There are two sets of harnesses connected to the rubber thing in the crank case, and only the one got hot.. Also, the wire is covered in woven cloth type material, not regular plastic like regular wires. The harness that got hot has three wires in it... the other has two.

I traced this set of wires all the way to under the front fairing, and they are in the main wire loom that runs from the front to the back of the bike.

One other thing of note is that they only get hot when the bike is running... I left the key in the on position, but didn't start the bike just to test, and the wires didn't get hot.

Any help would be appreciated!

Smoak

[richardthescooter1]

My CDI is under my seat.

[hagedorn45]

Did you get any help with this i just saw that you posted it over a year ago. I had the same problem and man i was hoping some one had help on it. being as old as it is you may not have can you let me know if anyone answered your questions.

[rcq78]

Them wires are coming from you Stator,which is like a alternator on a car...You need to order the new connectors & replace then...Here is a website to get them from....http://www.oregonmotorcycleparts.com...rs.html....The ones from this site are better quality then the cheap ones that are on there now....The stator runs the electrical system on the scoot & yes,it only puts out juice when the scoot is running,it is located in the engine....The battery is basically only used to start the scoot...Motorcycles run basically the same.....Good luck..

[smoak]

Originally Posted by hagedorn45

Did you get any help with this i just saw that you posted it over a year ago. I had the same problem and man i was hoping some one had help on it. being as old as it is you may not have can you let me know if anyone answered your questions.

I ended up replacing the voltage regulator because it was getting super hot as well. I think I posted pictures somewhere maybe? I re-did the wiring harness and made sure all the wires/connections that got hot were replaced. I have not noticed any problems since then, which was last year and probably 1000 miles ago.

[bandito2]

Originally Posted by smoak

I ended up replacing the voltage regulator because it was getting super hot as well. I think I posted pictures somewhere maybe? I re-did the wiring harness and made sure all the wires/connections that got hot were replaced. I have not noticed any problems since then, which was last year and probably 1000 miles ago.

Sounds like the voltage regulator was going bad. What it does is convert excess voltage into heat that gets dissipated by those big fins on the regulator. It keeps the system from overvoltage to electrical components. It's AC voltage that is coming from the stator. If it can't shunt enough voltage off, then the AC output wires from the stator will heat up too. Sometimes enough to burn out windings in the stator or surviving that, will heat up lighter gauge wiring at the connectors. Lighter gauge wires will heat up faster since they have lower current carrying ability and the more they heat up, the less capable to carry current they become. So once they start heating up, it makes them more resistant which causes them to heat up even more. It's something that once it gets started, only becomes worse. I'm not sure when the voltage gets shunted; either before or after the rectifier which converts the AC to DC voltage by running it through diodes that allow voltage to flow in one direction only. Could be that the diodes were failing in the regulator and maybe allowing higher voltage AC to leak into the wiring.

But no matter, you got it fixed by replacing the voltage regulator/rectifier. Good call on replacing the previously heated wiring as well. Heat fatigues metal; the wires may have been made to be more prone to breaking.

BTW, I am no expert at electrical systems, but this is how I understand it to be. (and looking at my wiring schematic leads me to think this way too) If I am wrong about any of this, then anybody more knowledgeable/qualified should say so. I don't mean to confuse or mislead with errant info if any of it is incorrect. .