Topic: knocking noise at idle

[torick]

Hey my name is bobby and i bought my first bike recently, 1980 honda cb750. sweet little some info real quick on a possible problem. To start the bike, i have to rock it back a (~1000 rpms) is really rough and doesn't want to run without the choke till it's warmed but as soon as the rpms go higher the knock disappears. Is this a serious problem ?

 Thanks for the info and nice to meet you all.

Bobby

[KingCustomCycles.com]

Now would be the time to educate you on the differene between your bike and the SOHC that this site is dedicated to.  In 1979, Honda introduced the DOHC 750.  This marked the end of the Single Overhead cam production.  There are obvious differences in the engine and several more subtle differences in frame, sheetmetal, wiring and electrical.  Any bike will benefit from a tune-up per the manual when first purchased.  The knock could be anything from a rod or main bearing failure to a loose header pipe.  Check the front of your engine in the area of the cylinder block, those engines were known for wearing through at that point with a loose cam chain and many were unsuccessfully repaired with JB weld.

[torick]

Ah so I'm not even in the right place. Thanks for the info