Topic: CB750 front sprocket/ output shaft.

[robrffr]

On the engine we've put in to my mates CB750, instead of the usual fixture arrangement, ie retainer held on to sprocket by two small 10mm bolts, this one has a bolt in the middle of the shaft, and th sprocket is different, it's a e331T15. The old engine used a E228T18. But no of the manuals me mate has shows that type of fitting!! Any ideas?

[Johnny5]

My CB750 only has one bolt securing the front sprocket.

[scondon]

On the engine we've put in to my mates CB750, instead of the usual fixture arrangement, ie retainer held on to sprocket by two small 10mm bolts, this one has a bolt in the middle of the shaft, and th sprocket is different, it's a e331T15. The old engine used a E228T18. But no of the manuals me mate has shows that type of fitting!! Any ideas?

"e331T15" - Am guessing from this # that the sprocket is a 15 tooth/ 630 which is standard on the 77-78 750k engines, like johnny5 has. You should be able to use a 18T/530 sprocket with little fuss. I use them on my '78 750, single bolt holds them on.

[Johnny5]

Yeah, my 750K7 had originally the 15t front which I converted to a 530 chain and 17t front 48t rear.

[Old Scrambler]

Now that you have a K7 or K8 motor in an older frame.......note that the rear wheel/sprocket will be off-line by 10mm.  The later models have a longer (wider) countershaft sprocket mount for larger chain and bigger tires on the rear.

[mrosso]

Now that you have a K7 or K8 motor in an older frame.......note that the rear wheel/sprocket will be off-line by 10mm.  The later models have a longer (wider) countershaft sprocket mount for larger chain and bigger tires on the rear.

Looks like I'm in the save F**** boat. I just found out I have a '77 CB750 K7 motor and a '71 K frame. Is there any way to get this combo to work? Can you swap the rear sprocket on the '71 hub for a '77 sprocket?

[754]

Just swap the rear sprocket carrier, or shim out your sprocket, if you have enough bolt.