Topic: 630 to 530 quick and dirty details

[700504]

I've got my finger on the button ready to order JT 17-48 sprockets and an std RK 530 chain to convert my 1978 cb750k to the smaller chain. I've searched the forum a few times to confirm I'm getting the right stuff.  Just wanted to know if there is anything I'm missing, do I just use the same single bolt and torque it down on the front sprocket (I know the thickness differs between 77-78 630 sprockets and earlier 530 sprockets, so the bolt will be touching the sprocket and not the output shaft). Any info is appreciated!

[70CB750]

The 78F engine came to me already converted and the bolt kept loosening up. Finally used longer bolt and washers to create space between the sprocket and the bolt.

I believe the small movements of the sprocket back and forth were responsible for the bolt getting loose.

Does it make sense?

[700504]

The 78F engine came to me already converted and the bolt kept loosening up. Finally used longer bolt and washers to create space between the sprocket and the bolt.

I believe the small movements of the sprocket back and forth were responsible for the bolt getting loose.

Does it make sense?

Very good to know, thank you. I know the 630 sprocket jiggles a bit, but I think I've read the 530 wont since it's wider, is this correct?

[seanbarney41]

I had a 77k motor that had a true correct conversion sprocket so I know they were out there at some time in the past.  But whenever I try to order one I end up with one with the shoulder on both sides.

Another option is to have a machine shop grind the shoulder off one side.  Cheaper quality sprockets may be soft enough to mill.

[700504]

I had a 77k motor that had a true correct conversion sprocket so I know they were out there at some time in the past.  But whenever I try to order one I end up with one with the shoulder on both sides.

Another option is to have a machine shop grind the shoulder off one side.  Cheaper quality sprockets may be soft enough to mill.

That seems like a reasonable option. When I bought this bike in particular, it had a 530 chain on it, with both shoulders and just the single bolt holding it on.

I thought, 'well why not return it to it's stock 630 state'. But after using 630 chains for the last couple years, the cons outweigh the pros. They aren't on the shelf in any shops in my area, but the 530's are. And I've seized 4 of them...just too much damn weight flinging around, and they lose their lube in less miles than a 530, in my experience.

[700504]

I had a 77k motor that had a true correct conversion sprocket so I know they were out there at some time in the past.  But whenever I try to order one I end up with one with the shoulder on both sides.

Another option is to have a machine shop grind the shoulder off one side.  Cheaper quality sprockets may be soft enough to mill.

And so you've ran the double shouldered 530 sprockets on the 77 shaft and not experienced any problems?

[seanbarney41]

Sort of, I had one shoulder milled off once, and another time sprocket was too hard and had to be ground.

When I got my 750f, had the original 630...that mofo was all rusty from sittin...cleaned it up and it still lasted to 28,000 miles

[Mr Freeze]

I bought a JT 530 kit just like yours. Just use some blue loctite and install that drive spocket with the bolt and torque to spec. Everything fits perfectly. You shouldn't have to mill any shoulders off. Double check the alignment with the sprockets installed in there's any question, otherwise you should be good to go.

[Jerry Rxman Griffin aka MuthaF'er]

The CB650 sprocket only has a shoulder on one side.

[700504]

The CB650 sprocket only has a shoulder on one side.

I have a cb650 but its a 630 chain

[700504]

So I was digging through my parts bins last night and came across a 530 front sprocket with no shoulders at all. I grabbed my vernier caliper and lo and behold is was the same width as a stock 630 sprocket! I threw it on, as well as a rear sprocket and grabbed a chain the was still good off another 750 I have lying around and BAM! 530 conversion with a legit 530 conversion front sprocket. It's so much smoother!

[700504]

The CB650 sprocket only has a shoulder on one side.

Wow your right! http://www.jtsprockets.com/catalogue/model/520  http://www.jtsprockets.com/catalogue/model/564

These two links show the cb650 1979 to 1981 with a 530 and the cb750 1977 with 630, the sprockets are the same width. I think we just found a direct conversion. I'll be ordering one of these cb650 sprockets when it's time and I'll report back with the results.

My cb650 is a 1981, but it has a full 630 chain set up for some reason?

[700504]

http://www.ebay.com/itm/322200895227 I'm going to pull the trigger on this, I'll post fitment comparison pics after I get it to show the conversion from 630 to 530.

[cb650]

The CB650 sprocket only has a shoulder on one side.

Wow your right! http://www.jtsprockets.com/catalogue/model/520  http://www.jtsprockets.com/catalogue/model/564

These two links show the cb650 1979 to 1981 with a 530 and the cb750 1977 with 630, the sprockets are the same width. I think we just found a direct conversion. I'll be ordering one of these cb650 sprockets when it's time and I'll report back with the results.

My cb650 is a 1981, but it has a full 630 chain set up for some reason?

who knows who jacked around with parts over the years.  All sohc650's cam with 530 chains.    I seen on once with a drum front.  NOT even close to factory.

[700504]

The CB650 sprocket only has a shoulder on one side.

Wow your right! http://www.jtsprockets.com/catalogue/model/520  http://www.jtsprockets.com/catalogue/model/564

These two links show the cb650 1979 to 1981 with a 530 and the cb750 1977 with 630, the sprockets are the same width. I think we just found a direct conversion. I'll be ordering one of these cb650 sprockets when it's time and I'll report back with the results.

My cb650 is a 1981, but it has a full 630 chain set up for some reason?

who knows who jacked around with parts over the years.  All sohc650's cam with 530 chains.    I seen on once with a drum front.  NOT even close to factory.

Yeah absolutely, I've had 6 sohc's in total, none of them came close to having all the stock parts. Another reason why this forum is such a treasure, so much helpful information.