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Post by brinkkl2000 on May 1, 2017 15:10:34 GMT -5
I have a 50cc 2 stroke scooter here, Wahoo brand I guess. It has a 12" wheel which from my research suggests a long case. The old belt blew to pieces and could not get any numbers on it. The new belt that was put on is a Gates Powerlink 788 18.1. The scooter will barely move, which I believe is because this belt is too short. It is riding near the bottom of the "secondary clutch," and is very tight. I have found where they say to get a 729 17.7 30 belt for along case, but that appears to be shorter yet (788 vs 729). What should I be looking for?
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Post by hillbillybob on May 1, 2017 17:46:25 GMT -5
How about an engine code? It may let us know just what you have. There are some oddball scoots out there that take something other than standard size belts. Such as this one at ScrappyDogs"This is the ultra rare, hard to find 836 belt that you must use on your QJ1P39QMB-3 engine code. Some have mistakenly called this a 835-17-30. This is a strange amalgamation of 2stroke transmission CVT components mated to a modified 50cc 4stroke engine case. These are the shorter belts. If you've got a Baja SC50 Sun City or maybe another with this engine, you need this belt. $24. "
Check that engine code |
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Post by brinkkl2000 on May 2, 2017 15:35:29 GMT -5
Stamped on the case is
CL1PE40QMB
*40040429*
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Post by brinkkl2000 on May 2, 2017 15:51:41 GMT -5
Also, where should the belt be riding on the rear clutch. I am familiar with snowmobile clutches and it would be what I think of as the secondary. I have seen a couple different belt sizes for this code case. The top of the belt that is on it is riding about 1/2" to 3/4" below the edge of the sheave when brought back down to an idle. Should it be level with or slightly above, similar to a snowmobile?
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Post by hillbillybob on May 2, 2017 16:46:33 GMT -5
The 1PE40QMB does call for a 788 - 18.1 - 28 belt. The other one you mentioned is a mistake...it is not 729, but rather 792 - 16.6 - 30, which is also advertised as used on the 50cc 2 stroke 1PE40QMB units. 4mm longer, 1.5mm narrower, that's not a whole lot different.
Before I bought one, I'd make sure that the rollers are seated properly in the variator, if not, the variator halves won't open, or separate fully.....causing the belt to ride deeper in the clutch pulley.
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Post by brinkkl2000 on May 4, 2017 10:57:38 GMT -5
Ok, so assuming the belt is the correct size then, I pulled the variator apart and made sure the rollers were seated properly. They looked good, but I don't know if it something that can be visually inspected good or bad, unless they are obviously shot. The scoot starts up and runs perfect on its stand. The engine runs through its full operating range. When I jump on it, I get about 20 mph, and then engine just bogs out, almost to the stalling point, when I give it full throttle. Again, I can stop and put it on the stand and it revs up perfectly. I have already cleaned out the carb and checked for air leaks (the intake has cracks in it but is not leaking as verified by spraying carb cleaner all over it,) put a new plug in it, checked air box for cracks and cleaned the air filter out, checked all the vacuum lines and petcock.
I should also add, that it seems this problem only showed up after putting the new belt on. Many other people are suggesting to re-jet, but nothing changed other then the new belt. |
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Post by chewbaca on May 6, 2017 13:01:58 GMT -5
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Post by geo49 on May 18, 2017 2:26:26 GMT -5
There's a 788-17 belt that would be a better fit than the 788-18. 18mm sounds a little wide and would hurt performance. That or the 792-16.6 belt would work and might be the stock size. Also your roller weights will show flat spots when they get old and that will affect your performance as well. A weak torque spring could keep your belt from returning to the outer portion of the rear pulley when back at idle.
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