Potentially a stretched oil pump chain for which there is no tensioner just replacement.
Adjust your crank balancer too as this may help a little bit

 

Hi and thanks Sprock. I will definitely check it out as I don't believe the engine has to come out to replace the chain? Although I do not understand, if it is the oil pump chain, why the rattle only happens when the engine is under load? If it's in neutral and cold and you rev it there is no noise? How do you know by how much to adjust the crank balancer?

Best Regards
John A

 

Read the crank balancer how to by none other than Kilgore-fishstick-Trout
aka KilgoreTrout

Yeah the oil pump drive chain more specifically the oil pump sprocket maybe
be loose, missing teeth , or keyed out

 

OMG Sprock! I honestly do not know how to thanks you enough!!! I adjusted the crank balancer as per the instructions and the rattle is much much much better. It's now insignificant! After all these years............ You simply cannot imagine how much this means to me!!!


THANKS SO MUCH!!!!!!!!!!!!!!!!!!!!!!!!!!

In your debt
John A

PS: Given that this helped any idea what it might be?

 

I would never have thought that the balancer being off would change as the bike warmed up. Good one Sprock.

Perhaps a good ol' fashion carb sync would be the ticket to smooth things out further.

 

& as TBT said ^^ a proper carb sync will make it run like Velvet

 

And don't forget, taking her up a notch or two in jetting to get rid of the factory lean condition and ethanol. Then, using S.B.'s stick coil magic to get the best out of her. Those things right there will make her young again at bargain prices.

 

Hi folks. The rattle is still there but so much better. Something is worn out but I know not what.

I had the old girl fitted with a Dynojet kit last year. On the Dyno she is still chucking out 119bhp at the rear wheel and the power curve is straight and true! (Better than any modern fuel injected electronic masterpiece I'll wager!!) I was told that this figure was as good as a new engine??

Still, she went like a dream yesterday and I was not put to shame by my friends Hyabusa which is falling to bits having done just 30000 miles!!!

Very tempted by the stick coil mod but I don't think I could bring myself to fit a non standard part!

I am also very tempted by a brand new unused engine currently for sale on eBay. The part number is SC09. Does any one know what year this engine is? I don't want it if it is one of the lower powered ones pre 1990.

Cheers
John A

 

I keep my stock coils in a drawer out in the garage. I can sleep at night just knowing that they're there. LOL

 

Better than any modern fuel injected electronic masterpiece I'll wager!

Not better than the Blackbird Metropolitan !!! Someone went down this track not long back and lost......miserably......lol. Glad to hear your bike is better.