New, not wrenchy but learning, help!!

[Canadian cb'r]

Hallooo from the great white north. My current ride is a 1980 CB750K the pic is from my first day out March 10/'15. Little by little I am figuring out what I can work on what I can't, and learning what I need to work on the "can't".
 The bike runs well with 63k+kilometers on the odometer. It has developed a knocking sound as I accelerate away from stopped or slow rolling corners. It stops as I accelerate past 20-30 kph. With the bike on centre stand, running at idle in 1st gear, using the screwdriver stethoscope trick: engine sounds good but the is a roughness when I hold the driver to the motor over the drive gear. The sound when riding sounds like the CV joint going out on my old Honda Civic.
Any hints as to how much trouble i'm in?? Any help is appreciated,
Cheers

[TOOLS1]

I wonder if you are having ignition knock from low octane gas. This happens when you are accelerating in mid range.
TOOLS

[Re-run]

Yeah, it does sound like knock from low octane or poor fuel. However, just to be sure, you may want to check the tension on the 2 cam chains, check valve clearance, and since it is coming from around the front sprocket; maybe check that to make sure it is tight. Just in case.

If the gas was in the tank for a while though, such as winter storage, you might want to drain it and put it in your car. Especially if you have ethanol in your fuel. Ethanol has a short shelf life. If you used Sta-bil in the fuel, I would still dump it. I have never had good luck with that garbage. I use seafoam for fuel storage.

[surfish95747]

Re-run, just wondering, how do you use seafoam for fuel storage. I have actually been looking for directions on how to use seafoam and can't really find any. I know I am just missing it. Thanks man!

[TOOLS1]

Just put a few oz's in your gas. That simple.
TOOLS

[LukeM]

From the Sea-Foam website:

Normal gasoline grades (including 10% and 15% ethanol blends)

1 oz. Sea Foam Motor Treatment per gallon of gasoline

Can mix up to 2 oz. per gallon of gasoline if necessary. Mixing at less than two-thirds oz. per gallon will impair the effectiveness of Sea Foam Motor Treatment.
- See more at: http://seafoamsales.com/recommended-mix-amounts/#sthash.x5u3fYg9.dpuf

Luke M

[Re-run]

Just as tools said. You put some in, I do about half a can. Fill the tank to the brim and into storage it goes. Been doing that a few years now and it has worked fabulously. Even in my fz6 which is touchy about its fuel.

[surfish95747]

Ahh, I feel silly . Should of looked harder on the website! Thanks guys!

[Canadian cb'r]

Not the fuel, have been running highest octane possible since I took possession of the bike and have had no problems that way. At first I thought the chain might be loose, sounded like chain slap but no joy on tensioning the chain. I did notice that the drive sprocket had play in it. 3'o'clock to 9'o'clock the sprocket can move to and away from me a couple mil. when I had put everything back together the noise stopped for couple rides. bearing on that sprocket starting to go?