Transmission question

[Shadow57x]

I just bought this 53cc engine kit I was wondering if it had the same 78mm clutch set up was say a pocket bike I'm looking to use the transmission to put a 63.3cc 2 stroke kesei clone engine on my bike. Thanks in advance.

 

[Sidewinder Jerry]

The weak point on these chain transmissions is the shaft with the small sprocket. There are videos where that shaft breaks right at the sproket. The dual chain might be a little better but the shaft is the same diameter on both. The belt drive is the way to go for sure, especially with the 5:1 ratio.

These are the only videos I could find on failures. Perhaps you could post the videos you're referring to.





As for the transmission the OP has recently purchased it's new on the market. So I'm reserving judgement until he disassembles it and post pictures of the inside of it.

 

[michael whiteman]

Thanks for the great video Jerry. Too bad you lost the most important part. Can't count the number of times I've done that. Interesting to see the oversize output shaft turned out to just be a useless sleeve spacer. The main design flaw of these transmissions is the fact both shafts can only be supported by ONE bearing. The force from both chains are in the same direction trying to tear the bearing from it's mounting. You would need two spaced out bearings on a shaft to prevent this. A new case could be cast that would extend out to the 10T output sprocket. A second suppport bearing could be located there, which would be a good fix, but they will never do that.

Bikeberry has made a newer video which doesn't show the competitors broken shaft. Probably because their design is not all that much better. You can see the shaft I was referring to at the 1:38 mark in the video below. The teeth tend to break off right where that tiny machined groove appears. Personally, for worry free longevity I would not even consider a noisy chain drive trany. There are no issues with the belt drive model.

 

[Sidewinder Jerry]

Thanks for the great video Jerry. Too bad you lost the most important part. Can't count the number of times I've done that. Interesting to see the oversize output shaft turned out to just be a useless sleeve spacer. The main design flaw of these transmissions is the fact both shafts can only be supported by ONE bearing. The force from both chains are in the same direction trying to tear the bearing from it's mounting. You would need two spaced out bearings on a shaft to prevent this. A new case could be cast that would extend out to the 10T output sprocket. A second suppport bearing could be located there, which would be a good fix, but they will never do that.

Bikeberry has made a newer video which doesn't show the competitors broken shaft. Probably because their design is not all that much better. You can see the shaft I was referring to at the 1:38 mark in the video below. The teeth tend to break off right where that tiny machined groove appears. Personally, for worry free longevity I would not even consider a noisy chain drive trany. There are no issues with the belt drive model.

I know in my Staton shift kit the bottom bracket cups have 2 sealed bearings in each cup. It's the same with a Staton Inc rear hub 4 sealed bearings total. It'd be nice if this new transmission has been designed better. Though judging from the size of it looks like a 3\1 reduction. I guess we'll know soon when Shadow57X post pictures of the inside of it.

This one seems to have some good potential. It's an actual gearbox with a 4.7\1 reduction.

 

[Will'smotobikes19]

I'm looking to use the transmission to put a 63.3cc 2 stroke kesei clone engine on my bike. Thanks in advance.View attachment 210640

How are you going to mount the kasei? Yes they both use 76mm clutch and 78mm bell. Possible that it has a few gas tank mounts the gx50 has 2 bolts on one side then uses 2 bolts that hold the pull starter on but they are horizontal. Not sure about a kasei.

 

[Shadow57x]

Ok finally got this in today and in my opinion seems to be built pretty well. I went ahead a greased it pretty good.

 

[Sidewinder Jerry]

Ok finally got this in today and in my opinion seems to be built pretty well. I went ahead a greased it pretty good.
View attachment 211035

Did you do a teeth count on the small and large sprockets? What does the other side look like? Could it be completely disassembled if you needed to do so? It looks like a freewheel is on the large sprocket. Can you tell what kind of bushing or bearings is being used where the shafts are? Hopefully, they're at least oil-lite bushings and not just plain brass. The best case scenario would be double sealed bearings.

 

[Shadow57x]

I'll disassemble it more when I get to building the bike it's going on. For right now I want to keep it intact so I'm not losing anything.

 

[Will'smotobikes19]

Can you tell what kind of bushing or bearings is being used where the shafts are? Hopefully, they're at least oil-lite bushings and not just plain brass. The best case scenario would be double sealed bearings.

You can see behind the small sprocket a bearing these chain drive transmissions all use bearings.