Author Topic: 1978 CB750F2 - Chain and Sprockets  (Read 697 times)

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Offline cowboycletus

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1978 CB750F2 - Chain and Sprockets
« on: March 13, 2021, 01:31:55 PM »
Hi guys, it’s starting get warm again and I have work I need to do on my bike. I got this machine as a Covid project and spent most of last summer working on it. In October I did a road trip down south to see some friends and made it about 1200mi before my chain broke. I haven’t ridden it since, but with the seasons changing and warmer weather arriving it’s finally time to get cracking on it. My questions are:

630 or 530? Does sizing down do anything for me? Or is 530 just a more common chain size and therefore have more sprocket options...

I’m going to replace the sprockets as well...I’d love to get 5-10mph more out of my cruising range. How much would a move like that effect bottom end performance? What sprocket combinations will yield that result? I’m a pretty conservative rider so ripping away from red lights isn’t much of a concern...but I don’t want to sacrifice enough performance that I won’t be able to out maneuver cars. For reference, at 5000rpm/5th gear I get 65mph, I wish that was more like 70-72mph.

The chain break happened while riding in 4th gear. Without the chain in place I’m uncertain on how to shift back down to neutral. Can I replace the chain/sprockets by depressing the clutch lever, zip tieing it in that position, and when finished get back down to neutral by rocking the bike back and forth like normal?

Thanks in advance guys. I’m looking forward to tinkering outdoors again.

 

Offline 70CB750

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Re: 1978 CB750F2 - Chain and Sprockets
« Reply #1 on: March 14, 2021, 03:11:21 AM »
On F3 i run 17/48 and 530 chain.  As far as rpms and speed - there is a calculator somewhere here. If i find it i will post it. 

You should be able shift down without the engine running - just viggle the output sprocket if needed.
Prokop
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I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
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2006 KLR650

Offline robvangulik

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Re: 1978 CB750F2 - Chain and Sprockets
« Reply #2 on: March 14, 2021, 03:19:50 AM »
« Last Edit: March 14, 2021, 03:28:18 AM by robvangulik »

Offline 70CB750

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Re: 1978 CB750F2 - Chain and Sprockets
« Reply #3 on: March 14, 2021, 03:59:17 AM »
Here
Prokop
_______________
Pure Gas - find ethanol free gas station near you

I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
Sidecar


CB900C

2006 KLR650

Offline cowboycletus

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Re: 1978 CB750F2 - Chain and Sprockets
« Reply #4 on: April 02, 2021, 01:24:00 PM »
Alright, so I’ve got all parts finally. I ended up just adding a tooth to the front sprocket to make it 15/43. That should be the subtle change I’m hoping for.

As I’m preparing mentally for getting this done over the weekend it occurred to me, how do I remove the front sprocket without already having a chain on to provide resistance? To recap, the chain broke last season while riding. So it’s currently still in 4th gear. Would the engine provide enough resistance to loosen the sprocket nut?

Offline robvangulik

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Re: 1978 CB750F2 - Chain and Sprockets
« Reply #5 on: April 02, 2021, 04:01:50 PM »
Wedge a (fitting) piece of wood between sprocket and engine casing....