How to change a belt on a 50cc 139qmb Chinese Scooter Easily
Chinese scooters are undoubtedly one of the most popular forms of cheap transportation that has hit the U.S market. One thing that is going to happen at some point with your 139QMB 50cc Chinese scooter will be belt failure. Scooter belt failure almost happens without warning but with these simple steps I will show you how to replace the belt on you Chinese 50cc 139qmb scooter.
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Instructions
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First you will need to take off the CVT cover from the engine. This cover is held in by several bolts as seen in the picture
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When you have pulled the case cover off, There will more than likely be a shredded belt as well as black debris and dust that must be cleaned out thoroughly before a new belt can be installed. Double check both the variator pulley and rear clutch pulley are free from the worn belt.
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The next step is to remove the outside half of the variator pulley (fan pulley on the crankshaft) by way of a 17 mm nut. This is the most difficult part of the process because you must keep the engine from rotating to get the nut off. One of the ways of doing this is to wedge a big enough screw driver or block of wood between the engine case and the pulley to keep it from slipping. If you do not feel comfortable doing this method, there are specialty tools available to do this without fear of damaging your scooter. Check out the link at then bottom of this article.
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After the nut has been removed, pull off the variator assembly, being careful to note the reinstall arraignment. Inspect the rollers inside, If they have large flat spots and or are broken, replace these as well. After you have inspected these parts, reinstall the variator less the fan pulley half.
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Now you need to check the rear clutch pulley for smooth operation. Take both of your hands and grasp the pulley as seen in the picture. Make sure that pulley can move freely when compressing with your fingers.
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Compress the rear pulley apart again ,installing the belt on this pulley first. Allow your self enough slack to loop the scooter belt back on to the crankshaft where the other half of the variator fan pulley half will be reinstalled after.
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When you have reinstalled the pulley half on the crankshaft, double check that the 17mm retaining nut is on tight to ensure the variator will not come loose while driving your scooter.
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When buying a new belt for your 50cc 139QMB based Chinese Scooter, Keep in mind that your riding habits affect the life of the belt. Typically belts can last from 2000 to 8000 miles with normal usage. Kevlar belts are available as a heavy duty option for those that have modified scooters and or for people who tend to be rougher with their driving style.
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Tips & Warnings
Want to make your Scooter go 50 MPH+? Check out some of my Related articles down below!
Click on the link available below to purchase a replacement drive belt for your Chinese made 50cc scooter.
Resources
- Photo Credit scootusa
