Knocking from rear or middle of CBF1000

[FLIZ]

Re the “knocking noise” check the engine mountings, especially the front hanger mounting
bolts they could be loose. I recall seeing a post somewhere that these bolts had snapped/sheared off. Be careful when check tightening them, the threads could be corroded in the engine.

[BigGinger]

Thanks!

[Art]

Unclear what the symptom is here. Is this the same pre wheel bearing replacement knocking? Is it a knocking or heavy clicking? Is the noise only heard when the starter button is depressed? When the noise is heard is the starter motor spinning and cranking the engine? I'm thinking the starter relay is clicking/knocking (switching on and off) due to low battery voltage or poor CCA. This symptom is normally described as a fast clicking but get very loud and sound more like a knocking.

Since this is only happening from cold when the battery voltage is at its lowest I'd connect a multimeter across the battery terminals and see what the voltage drops to when the starter button is depressed and you hear the knocking.

Maybe invest in a  mechanics stethoscope  and get down and dirty to pin point the source of this knocking.

Other suspects would depend on the source of the knocking. If you're sure its coming from the starter motor its more likely to be the starter motor clutch than the starter motor itself. I doubt it would be the engine mounting bolts but an easy enough job to run over them with a torque wrench.

[BigGinger]

I suspend the starter motor clutch. It wasn’t a click, I’m familiar with the symptoms of a low battery unfortunately 🤦🏼‍♂️

When I pressed the ignition, I got the regular noises, then three loud knocks, the she fired up.

It didn’t happen this morning and I installed the aftermarket exhausts overnight. I don’t think that has anything to do with it but heyho.

[ivor hugh jarse]

My centre stand whacks the chain when hitting a pot hole - I've ignored it for years as it only happens rarely on a ride - been doing it for 12,000 miles with no problems

[Art]

Originally Posted by ivor hugh jarse

My centre stand whacks the chain when hitting a pot hole - I've ignored it for years as it only happens rarely on a ride - been doing it for 12,000 miles with no problems

 

I'd take a closer look at that, at rest there's a 50mm gap between the drive chain and centre stand the two should never contact each other, more likely to be one or the other. Its either a weak or broken centre stand spring or, a worn drive chain slider and/or too much slack in the drive chain.