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Post by macoryx on Sept 12, 2023 7:50:27 GMT -5
Hi all,
I have recently acquired an IceBear Rocket 49CC scooter, model number YN50QT-8 which I have not been able to find any specific resources on besides the generic Chinese scooter stuff.
I was having issues with starting when I discovered that the bendix was completely worn in the scooter and would not automatically retract and likely could not engage as well.
I have since replaced the bendix with a new one, and to my dismay I heard a grinding sound from the CVT while riding my scooter this morning. It seems as though the new bender is not failing to disengage. I have since tried to start the scooter back up with the electric start and it makes the classic whirring sound as if the bendix will not engage again.
The kickstart is the only way I can get it started, but it makes a horrific grinding sound. Please let me know if you have any ideas.
Best
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Post by macoryx on Sept 12, 2023 8:56:32 GMT -5
Update: The variator fan was completely destroyed upon opening it up along with some damage to the starter bendix. What could be causing this??? This is the second time this has happened.
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Post by macoryx on Sept 12, 2023 9:00:27 GMT -5
I will try to post some pictures when I get back home.
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Post by GrumpyUnk on Sept 12, 2023 10:37:22 GMT -5
Look at both the side case and the CVT cover for the bushings that support the Bendix. I bet you are missing one or both. People get a new CVT cover, and plop in the kick start stuff, and ignore the starter bushing. It is small but keeps the Bendix gear in position to mesh. Without the bushings, the Bendix can flop around a whole lot and mesh willy-nilly with the variator teeth.
If you look at an exploded view, you will find the bushing. If you have an old CVT cover, you may be able to extract the old bush and re-use it. Fill the opening with grease, and fit a shaft that is somewhat tight fit, whack on the end of the shaft. Some use bread mixed with ??? as a 'goo' that performs like a semi-liquid. When you whack it, the goo gets behind the bush and applies force to the inner surface of the bushing, kind of like a piston. Or maybe something else. Don't forget to check the case side as it also has a bushing.
tom
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Post by macoryx on Sept 12, 2023 12:09:09 GMT -5
Look at both the side case and the CVT cover for the bushings that support the Bendix. I bet you are missing one or both. People get a new CVT cover, and plop in the kick start stuff, and ignore the starter bushing. It is small but keeps the Bendix gear in position to mesh. Without the bushings, the Bendix can flop around a whole lot and mesh willy-nilly with the variator teeth. If you look at an exploded view, you will find the bushing. If you have an old CVT cover, you may be able to extract the old bush and re-use it. Fill the opening with grease, and fit a shaft that is somewhat tight fit, whack on the end of the shaft. Some use bread mixed with  as a 'goo' that performs like a semi-liquid. When you whack it, the goo gets behind the bush and applies force to the inner surface of the bushing, kind of like a piston. Or maybe something else. Don't forget to check the case side as it also has a bushing. Here are some pictures:  drive.google.com/file/d/1lcGm5fFhMtXr0gHIpwyjHxvGzJeCy-Ba/view?usp=drivesdkdrive.google.com/file/d/1qVkFvld6TT5fBHmcgIJ4ZN_k5znbF7wa/view?usp=drivesdk |
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Post by geoffh on Sept 12, 2023 15:19:12 GMT -5
Macoryx,grumpyunk is referring to the bush top right in your first picture and does look broken,that belt looks newish and the variator may have been reassembled wrongly,a parts diagram is needed to help you check.
Geoff
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Post by macoryx on Sept 12, 2023 16:04:03 GMT -5
Macoryx,grumpyunk is referring to the bush top right in your first picture and does look broken,that belt looks newish and the variator may have been reassembled wrongly,a parts diagram is needed to help you check. Geoff Crankshaft splines are completely stripped… after taking it apart again earlier I noticed that the big variator gear had no threads on the inner circle. I replaced it with a new one along with a new variator assembly as a whole. I got it working and then immediately afterwards the crankshaft itself had stripped completely. I am giving up on this scooter, it is built like complete garbage. |
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Post by geoffh on Sept 13, 2023 15:31:32 GMT -5
That's a shame but there is not a fix for a stripped crank,it,s worth noting that the failure was probably caused by the belt fitment so more garbage repair than garbage scooter,a hard way to learn though  Geoff |
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Post by macoryx on Sept 13, 2023 20:09:22 GMT -5
That's a shame but there is not a fix for a stripped crank,it,s worth noting that the failure was probably caused by the belt fitment so more garbage repair than garbage scooter,a hard way to learn though Geoff Am going to attempt replacing the crankshaft, which will be a very involved process but can sort out the other issues while the engine is apart. I’ve found some good resources on here to assist with this task. It is definitely not ideal, but I think with a good starting point the scooter can get a fresh breath of life that it deserves. |
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sinfull
Scoot Enthusiast
Posts: 413
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Post by sinfull on Sept 14, 2023 3:28:13 GMT -5
easier way is just go to Google and order a whole new engine, Amazon can have it delivered next day even, 2 bolts and you can have a fresh engine installed and riding next day.
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Post by macoryx on Sept 14, 2023 9:16:50 GMT -5
easier way is just go to Google and order a whole new engine, Amazon can have it delivered next day even, 2 bolts and you can have a fresh engine installed and riding next day. Do you have a link? I didn’t see any 139QMB on Amazon prime. |
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Post by GrumpyUnk on Sept 14, 2023 10:11:51 GMT -5
Do you have any pics of the stripped spline area? I was thinking that a Woodruff key or a square key might be fitted by machining a groove in the crankshaft and one in both variator and the toothed plate.
If you don't care about messing up a variator/etc, you could use a drill to make a spot where a round key(the drill bit...) could be inserted to lock the crankshaft to the various bits.
IOW, drill a hole that intersects the crankshaft and the parts mounted. Stuff a short drill remainder of the same size into the hole, and put the nut on to hold everything. Who knows, it might work.
tom
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Post by GrumpyUnk on Sept 14, 2023 10:22:57 GMT -5
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Post by macoryx on Sept 14, 2023 11:09:57 GMT -5
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Post by geoffh on Sept 14, 2023 15:28:21 GMT -5
Consideration, when you fit the drive belt make sure it is pushed deep into the rear pulley,this will ensure that it is loose/free at the variator when tightening the nut up ,buy a variator locking tool to do this job and don't,t forget that broken bush  Geoff |
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as a 'goo' that performs like a semi-liquid. When you whack it, the goo gets behind the bush and applies force to the inner surface of the bushing, kind of like a piston. Or maybe something else. Don't forget to check the case side as it also has a bushing.
