69 norton commando primary sound.

so on my 69 commando 750 it runs great got the transmission back together no leaks. went to ride it and it had done this before. when you get it up to temp and riding at and when yo come to idle you can hear something that sounds like a rod knock. ive replaced the primary stator rotor and new stator as well as clutch hub bearing. i know ive heard of the stator rotor rotating on the crank end and the old one was loose so i replaced it. this has me worried. if it is a rod knock how can i tell?

If your primary chain is too lose, you'll get "chain slap" when you check up on the throttle. When you rev the engine the front sprocket tightens the top section of chain to pull on the clutch basket, so no slap sound. When you release the throttle, the inertia of the spinning clutch basket produces pulses of slack into the top section of the chain which cause it to "slap" the top of the chain case, hence the term "chain slap".

tighten the primary chain...

*Solid objects conduct sound better than air, so if you can create the sound by reving the engine, then you can use a screwdriver or some metal object against the engine to locate the source of the sound by placing the blade end on different locations on the engine and holding the handle against your skull... (yes, skull...)

o0norton0o said:

If your primary chain is too lose, you'll get "chain slap" when you check up on the throttle. When you rev the engine the front sprocket tightens the top section of chain to pull on the clutch basket, so no slap sound. When you release the throttle, the inertia of the spinning clutch basket produces pulses of slack into the top section of the chain which cause it to "slap" the top of the chain case, hence the term "chain slap".

tighten the primary chain...

*Solid objects conduct sound better than air, so if you can create the sound by reving the engine, then you can use a screwdriver or some metal object against the engine to locate the source of the sound by placing the blade end on different locations on the engine and holding the handle against your skull... (yes, skull...)

Click to expand...

i did that and could here it I pulled the primary and found a bunch of metal shavings what could cause the chain is tight.

There is a sequence to tensioning the primary in the workshop manual. If you do not get the sequence right then the rear chain will be able to pull the gearbox back and tighten the primary chain.

A tight primary chain is not good either. If there's too much slack then you get chain slap. If it's too tight it could deflect your gearbox shaft or the crankshaft and cause a catastrophe.

The thing is, if the chain is tight, you aren't going to have chain slap, because that only happens on a chain that's too loose. Check to make sure your crankshaft nut is shimmed properly and tight because it drives your front sprocket on to the crankshaft taper so your front sprocket is solidly fixed to the crankshaft. If it's not pressed on to the taper tightly, then it will eventually shear the key that holds it in place. If the sprocket isn't on the shaft tightly, it can make a clicking noise as it loads force to the crank when a piston fires, so you need to check that too.

If you are seeing some metal filings in the primary, unbolt the stator and inspect it's inner surface for possible contact with the rotor from either misalignment or too tight of a chain.