Scooterotica

I am just in the process of fitting a new JB corsa crank (60x107) however when fitted in the drive side it catches very slightly at the bottom of the stroke, the crank and bearing are fully 'home' however when fitted the mag housing it actually locks at the bottom.
I have checked the crank and the rod is slightly proud of the webs by 15 thou, is this normal? as my std crank is below the webs.
I am a bit stuck as dont want to be getting the dremmel on the casing.
Any ideas welcome

Did you change the drive side bearing, if so, check the plate is flat. If its an alloy one, replace it with a steel one. This sounds like the problem. If not, check the pin is not proud of the webs. If this dont work, go back to JB.

Yes new drive bearing and MBD steel plate, will re check the seating

Use a black marker pen on the plate before you put the crank back, this should show you where its rubbing.

DJB wrote:Use a black marker pen on the plate before you put the crank back, this should show you where its rubbing.

All sorted cheers, it was rubbing on the casing near the mouth where it chamfers etc... a quick 'tickle' with the dremmel and all's well
Cheers

yellow peril wrote:I am just in the process of fitting a new JB corsa crank (60x107) however when fitted in the drive side it catches very slightly at the bottom of the stroke, the crank and bearing are fully 'home' however when fitted the mag housing it actually locks at the bottom.
I have checked the crank and the rod is slightly proud of the webs by 15 thou, is this normal? as my std crank is below the webs.
I am a bit stuck as dont want to be getting the dremmel on the casing.
Any ideas welcome

are you saying the big end eye is sticking out past the circle of the crank webs when the rod is at bottom dead center i have seen this befor but on a rotax rodded engine the answere was to dremmel a grove in the back of the case so it didnt touch