GY6 50cc 139QMB specs. 50cc vs 80cc By dmartin95 (Read 2,797 times)

[dmartin95]

Ok, the stock bore and stroke of these two motors are as follows:



GY6 50cc Original Size: 39mm*41.4mm (49.4cc)



GY6 80cc Original Size: 47mm*41.4mm (71.8cc)





Now, almost all GY6 50cc parts are listed for the 139QMB. The 39 in that number is for the piston displacement size.



I'm also finding parts for the GY6 80cc, however I can not find a base engine stamp. Based on the size of the components, it should be a 147QMD, but I can not find an engine with this stamp.



When it comes to the bigger 150cc, there are some that have 54mm stud spacing and other with 57mm... Hence, the a and b case engines... I'm wondering if the 50cc's have a similar difference...



When it comes to the 50cc range, does anyone know any other stamps besides 139QMB?

[Alleyoop]

The other popular GY6 50cc is the 1P39QMB I believe all advertised 60+ 50s are just motors with BBKs.
Alleyoop

[jerryscript]

What about the "Secret 60s" that were all the rage a few years ago? Did they have standard engine stamps?

I have the BN139QMB, it is standard stud spacing, but taller head with the valves that are 3mm taller requiring a different set of rocker arms.