difference between JOG 50 and JOG 90 engine block?

[2stroketunah]

Hello.

I need some help to tell the difference between the Jog 50 and Jog 90 horizontal engine blocks.

I have a Yamaha Jog Aprio with the Yamaha Jog50 3KJ engine.  I recently purchased another block which i though was the same but when it came in it did not have the Yamaha 3KJ stamp on it like my stock motor.  however it looks identical to my 3KJ engine 

can anyone tell me how to identify between the JOG 50 and JOG 90 engine blocks

[2stroketunah]

[2stroketunah]

this is what the other case looks like.

casting is very ugly and uneven not sure if its even a Yamaha product. any advise on how to identify this case will be greatly appreciated.

[oldgeek]

Dec 2, 2023 16:30:33 GMT -5 2stroketunah said:

Hello.

I need some help to tell the difference between the Jog 50 and Jog 90 horizontal engine blocks.

I have a Yamaha Jog Aprio with the Yamaha Jog50 3KJ engine.  I recently purchased another block which i though was the same but when it came in it did not have the Yamaha 3KJ stamp on it like my stock motor.  however it looks identical to my 3KJ engine 

can anyone tell me how to identify between the JOG 50 and JOG 90 engine blocks

It looks like a chinese clone of a short case horizontal minarelli. They vary in quality. It uses different gears than the longcase minarelli and has room for only a 10" wheel.

Looking where the cylinder bolts up, it appears to be a standard 50cc case set. A set of 90cc cases would be opened up more in that area to accommodate the larger diameter of a 90cc cylinder.

Here is a thread that helps identify what you have.
49ccscoot.proboards.com/thread/999

Here is another with bearing info
49ccscoot.proboards.com/thread/6145/minarelli-clone-bearings-seals-torque

[2stroketunah]

Dec 3, 2023 6:45:14 GMT -5 oldgeek said:

thanks for the quick replu i appreciate the help.

the issue I have is I read througfh both the above mentioned post and the engine that I have does not fit any of the engines in either post.

the Final driveshaft that attaches to the rear tire is from a Jog50 with the 16 teeth splines like mention in the above post even the rear main bearing that the shaft sits on is sized for JOG50 engine, however,  the case I have doesn not have the 22mm case opening on the inside of the gearbox the opening is 30mm?

according to the post above if you have the Chinese motor there is a Needle bearing that the shaft sits on inside the gearbox along with the main bearing, but the needle bearing OD is 33mm with ID of 25mm.  the Chinese shaft is also thicker than the JOG50 shaft (chinese 20mm JOG 17mm).  the OD f the main rear bearing for the larger chinese shaft is 42mm and the JOG50 is 40mm.  the case that I have has a 40mm opening for the rear main bearing.

is there a needle bearing with a 30mm OD and 22mm ID for the inner part of the case?
   

[2stroketunah]

this post also gives great informaion on all the bearings and sizes.

weird part with my case is I have the JOG50 style gears but the case needs a Needle bearing instead of just sitting on the case like the normal JOG50.

the needle bearing that I need is not the same size as the ones that come with the chinese motor because I dont have the chinese rear shaft.

WTH!
49ccscoot.proboards.com/thread/27992/90cc-shortcase-clone-rear-wheel