driven pulley not opening

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dltempler

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This driven was a mess and I rebuilt it. Before I rebuilt it the spring was warped and the retaining ring was missing. Even then, it was shredding the belt because the pulley was not opening.

So, I rebuilt it (and the carb). Now it is properly assembled but it still isn't opening correctly and the belt winds up jammed.

Need a clue.
 
mike75925

mike75925

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briggs, what? sounds like you may be confused. the fly weights are in the driver, the garter springs only install one way as does the driven spring. there could be too much tension on the driven's spring, the driver's springs could be gummed up or rusted. are the weights even in the driver?
 
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dltempler

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The driver seems to be operating normally. As the motor accelerates the pulley closes and pulls the belt

I am not exactly sure how the driven is supposed to work, in other words whether it is open at throttle and closed at idle or what.

Mike pointed out the mistake with Briggs....the weights are in the driver and the driven spring only goes on one way.

I don't think it is the tension on the spring. When I put this spring in I had to load the spring to get the outer cam on. I suppose I could have used a different pre-set hole on the cam but this driven was doing the same thing before I rebuilt it and I was sure that the rebuild would correct the issue. After all, the spring was misshapen and the retaining clip was missing completely.

I could post pics but I am really not sure what they are going to show. I mean, the driven looks like every other one I have seen.

Hoping someone comes up with something clever.
 
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dltempler

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porsche930dude said:
if you have the preload set wrong it wont wind up. But the belt shouldnt get jammed either way
Click to expand...

the belt is getting stuck down in the pulley. It is getting pulled tight into the narrowest point on the pulley where is literally gets jammed. If the pulley opened up then the problem would not happen. But I am not sure whether the pulley is supposed to open at throttle or idle. It appears that it should open at throttle, at the same time the driver pulley closes.

And that seems to be the problem because this belt lock-up occurs at acceleration
 
Doc Sprocket

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In the driven, the belt starts high, and with acceleration, goes low. I'm not looking at my kart right now (in storage) but I would think that the driven has to open to accomplish this. So I'm guessing closed at idle, open at full speed. Check to ensure that all surfaces that need lube are properly lubed, and if you can turn the halves by hand ( I think you can, that they spread without any hitches. Maybe there's a bad, worn, or rusty spot where it catches part way?
 
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dltempler

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I think it is open at throttle and it closes at idle. This makes sense and toystory says that is the way his works.

As to the belt, the kart ran fine with the belt that was on it...at least for a while. It was during that time that the kid noticed a problem and ultimately that belt shredded. When replacing the belt for him I noticed that the outer cam was mispositioned and so I undertood a rebuild. I found the spring misshapen and the retaining clip missing. The jackshaft had been jimmied too.

I replaced all of the bad parts and put the thing back together. SEEMED to be fine. The kart had been sitting for several months and would not start so I took the carb apart, soaked it, cleaned the jets, blew it out and reset the idle screw.

Now it starts fine and it runs ok so long as it isn't throttled up too fast. If the throttle is hammered quick, that is when the problem occurs.

PS: The replacement belt was given to me with the kart when it needed fixing. It was purchased at a local kart and scooter store so I assumed it was the correct one but short of ordering one from American Sportworks I am not sure.
 
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mike75925

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how much slack is in the belt? with the belt off of the driven, twist and open it. when you have it as open as you can get it, fully release it like you are shooting a bow&arrows. if it doesn't close all the way back up, something is wrong with the slider bushing or the spring doesn't have enough tension. can you put up some pics? driven is to be closed at idle, driver open. you aren't by chance running a sym belt on an assym system or vice versa are you?
 
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dltempler

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The belt that is currently on there is an Infinity 669-18-10

The kart is a Manco 485 and the parts schematic shows part number 5959 for the belt.

I don't know if they are the same belts or not

EDIT: The Manco 5959 is an asymmetric belt and is replaceable with Comet 30 Series, 203589A, with a 3/4" top width. I have to find the dimension of that belt.

The Infiniti is 669mm long, 18mm wide, 30mm teeth spacing.

EDIT 2: They are not the same measurements. The Manco 5959 is an inch longer. I am not sure of the other differences if any but that length difference standing alone tells me that is a problem even if it is not THE problem
 
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dltempler

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there is enough wrong with the belt to cause me to wonder so I'll know more in a couple of days. Ordered and OEM replacement and we'll see. Thanks to everyone who chimed in.
 
mike75925

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if indeed slack is the issue, i just elongated the slots in my js plate to accomodate a smaller belt. i still have just enough room to tighten the rear engine bolts.
 
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