139QMB - No power under load, stalls

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139QMB - No power under load, stalls

Postby Beeblebronx » Thu Jul 20, 2006 6:04 pm

I've got a problem with my Qingqi scoot with the 139QMB motor. Here's the story:

I was riding it along and suddenly it made a horrible sound and died. Wouldn't restart. Got it home (finally) and suspecting an engine issue, I tore down the engine. Nothing. So, I put it back together. Next, I checked the drive belt, and there it was; the belt was broken and bunched up under the driving pulley. I pulled it out and lo, it started and idled! So, I get a new belt and put it on. Now the motor won't start unless I give it full throttle, or put it up on the work stand so the rear wheel can turn freely--if I hit the rear brake while it's idling, it stalls. I'm thinking it's a clutch problem but I'm not sure how to go about dealing with it. Nothing seems tight, and everything seems to turn smoothly without sticking. So, it might be a timing or mixture problem. I'm at the end of my rope here. Help!
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re: 139QMB - No power under load, stalls

Postby Smitty » Thu Jul 20, 2006 7:16 pm

Pull the front clutch off, and "reload" the rollers in correctly. When the belt breaks, the rollers get slung out of place. I ran into the exact same problem the first one I did.
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Thu Jul 20, 2006 7:28 pm

Ah ha! Thank you! Can you provide a little more detail about how to reset the rollers properly? I've never seen the inside of the clutch and I'd like to have some idea of what to look for. At least I know I <i>did</i> put the engine back together properly--I completely took it apart again, to see if I'd overlooked anything. I was getting ready to throw the damn thing off a cliff!
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re: 139QMB - No power under load, stalls

Postby Smitty » Thu Jul 20, 2006 7:38 pm

Yep ... try this http://www.mopedriders.org/viewtopic.php?t=3608
I made this post shortly after we created the Scooter Riders section of this forum.
I hope this helps.
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Thu Jul 20, 2006 7:46 pm

Beautiful! Yes, I think I'll be able to fix it tomorrow. I can't do it now, because I have to borrow an impact wrench from a nearby mechanic, but he's closed now. I'll let you know tomorrow how it goes.

I don't think I'd have figured this out on my own--at least not any time soon! The dealer doesn't even know, because when I told him the belt broke, he had no advice for me.
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Thu Jul 20, 2006 8:03 pm

Now that I've thought about it, it's sooo obvious in retrospect. When the belt breaks under full or near-full throttle, the sudden drop in engine load make the RPMs shoot up. The roller weights are thrown to the outside of the pulley and get stuck there. The result is like trying to start and run the thing in high gear! Of course, it's going to stall.

D'oh!
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re: 139QMB - No power under load, stalls

Postby maddog » Thu Jul 20, 2006 9:26 pm

you may want to check the rear drive pulley if it locks up it will break a belt, i see it happen all the time, take it apart then twist & pull it outwards if its locked its seized.
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Thu Jul 20, 2006 9:38 pm

Yeah, I am kinda wondering <i>why</i> the belt broke, but when I pulled the rear pulley to loop the new belt, I did just what you said, and the pulley expanded properly. The rear wheel turns fine when the belt is off. It might have been a defective belt.

But, it shows considerable wear in one area--the rubber is worn literally down to the fiber backing material. There's no way that amount of wear took place in the short time it took for the engine to stall out. I can't imagine what might have happened.
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re: 139QMB - No power under load, stalls

Postby Smitty » Fri Jul 21, 2006 8:35 am

I've seen them do that when people hold the rear brake and rev the engine extensively. This of course will hold the belt from turning (because the back wheel isn't), and the front variator wears the belt in that spot. Other than that, I can't think of any other cause?

From what Ive heard and read, those belts need replacing every few thousand miles.
Check your rollers, and inspect them for any flat-spots.
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Fri Jul 21, 2006 9:29 am

Well, this bike only has about 1000 miles on it. A belt shouldn't go THAT soon!
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Fri Jul 21, 2006 9:55 am

*sigh*

Ok, I've had a chance to pull the front clutch. One of the retaining clips is missing and the other two are broken. ALL the roller weights have flat spots on them, and one is missing. So, I need those. Anyone know where I can get these things fast and cheap? The only place I know of is where I bought the bike, but it's 30 miles away, and I can't get there since my bike is dead!
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re: 139QMB - No power under load, stalls

Postby Perry Manessis » Fri Jul 21, 2006 10:09 am

Yes, try Henry @ Scooter Brokers 305-305-7053, he's a great guy and has parts coming out of his ears. Just let him know you have a 139QMB 4 stroke motor.
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Fri Jul 21, 2006 10:24 am

Thanks, Perry, but he doesn't sell the parts individually, he only sells the complete clutch assembly for $39.99. I can't afford that right now. All I need are the 6 roller weights (preferably somewhat lighter than stock) and the 3 clips. I can't find anyone online who sells those parts separately.
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re: 139QMB - No power under load, stalls

Postby Smitty » Fri Jul 21, 2006 11:19 am

I used to could get the individual parts (rollers, etc.), but now they seem to be as much as the entire assembly! Seems that most people now prefer to sell the complete assemblies, as opposed to selling individual parts ... may be just as cheap to replace the whole thing?
Good luck!
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re: 139QMB - No power under load, stalls

Postby Beeblebronx » Sat Jul 22, 2006 12:36 pm

I found the roller weights here for $17.95. They are the correct size and weight for my clutch (I measured everything myself). But, I still can't find the three bearing clips. Gah!!
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