New 1980 CB750C Owner/Hobby Tinkerer Questions/ Journey

[cubicledaydreamer]

Good day all,

I am a new owner of a 1980 cb750c DOHC. The bike was bought as someone else's project bike. I am aware of some of those challenges but the deal was too good. Bike came with the frame, motor, rear ohlins shocks, delkevic exhaust, mo.unit, mo.unit wire kit, head rebuilt honed and planed, tuff side seat (not going to use), please many other items.

A very good deal at 1000 bucks. This also lends itself to the fact I am a tinkerer. I have started modifying the frame, different tank, transitioning to an r1 fork and brakes, custom wheels and brakes, among other things. I am doing a full rebuild on the motor (double checking the head).

I am curious on a few things.
1. I have read about woes of the carbs and pod filters. Has anyone created an elongated velocity stack and filter combination? Any luck there besides the stock airbox?

(Not my build)

2. Is there a good source for crankshaft bearings? Is there an easier way to determine the color bearing? The block seems to indicate b and a.

3. (Placeholder)

 

[Loose Chain]

One thing I see is the cylinders are in rough shape. Looks like someone tried honing and did a terrible job. The cylinders look like they will need to be bored and a new set of pistons. Good luck with the build.

 

[cubicledaydreamer]

One thing I see is the cylinders are in rough shape. Looks like someone tried honing and did a terrible job. The cylinders look like they will need to be bored and a new set of pistons. Good luck with the build.

Yes I am in the processes of rebuilding the motor as we speak.

 

[Loose Chain]

Yes I am in the processes of rebuilding the motor as we speak.

What type of pistons are you planning on using?

 

[cubicledaydreamer]

I was going to use the stock pistons... any other suggestions?

 

[Loose Chain]

You are going to have to bore the cylinders so the pistons you have won't work. Or are you saying you are going to use over sized stock Honda pistons?

 

[cubicledaydreamer]

I am curious if that's the case. Will check the piston ring gaps tomorrow. New rings sitting in the garage.

 

[Loose Chain]

Those cylinders are in too rough a shape to use. The one cylinder looks like someone tried to hone it and made a mess of it. Also that cylinder looks like there is some deep parts that the bad honing didn't even touch. By the time you hone the cylinders to get rid of the bad areas you will be way oversized on the cylinders.

 

[Loose Chain]

This is what it should look like after a proper honing. You may have to enlarge the picture to see the honing pattern.

 

[cubicledaydreamer]

I appreciate the photo.

 

[cubicledaydreamer]

@Loose Chain all is not lost

 

[Loose Chain]

Not good, but it will run long enough to get rid of it.

 

[brettp]

In other words, it needs a food re-honing. If not rebore.