Topic: CB 750 A drive chain rattle

[Kenny]

Hi all, just bought a CB750a as I am having problems with my left hand and going though it for next year, one thing that I have found is the drive chain is noisy on tick over which at the moment is rough so hopefully when I sort the carbs out and get it ticking over better I hope this noise will be gone. Are these chains a problem
 

[MCRider]

A dry poorly lubricated chain will be noisy. A worn chain will be also, doesn't fit down on the sprocket teeth nicely. Pins and bushings are worn.

Bike on centerstand, on floor facing chain. Push up on the bottom row of the chain till tight. At 3:00 O'clock on the rear sprocket, with 2 fingers, pinch and pull the chain away from the sprocket. If it pulls away far enough that you can see daylight between it and the sprocket, chain  is irretrievably shot.

[Kenny]

Hi now sorted carbs and running quite smooth but the rattle is when I turn the tickover down there is a real rattle from the gearbox. I remember my f1&f2 suffered from drive chain rattle from the engine/ gearbox, Is this common with hondamatic's.

[dave the welder]

yes it is especially with a lot of miles.properly sync carbs will help somealong with proper point setting and timing.do all that and it will probably still make a little noise at idle

[Kenny]

Fitted electronic  ingition and running well good, smooth tickover  but still a knocking noise from the transmition around torque convert area right hand side when on low tickover but now feel this is normal after watching some on YouTube they all seem to rattle. Ant opinions on this subject.

[Kenny]

Having watched a number of hondamatic 750's on YouTube it appears that  this knocking is common to these bikes but  with a  well tuned engine it is greatly reduced   So thanks for all the in put.

[stikman]

Carb sync helps alot.  Also, you may find a slightly higher idle will make the primary chain rattle go away.  The CB750K motors don't have this issue as there was room in their gearbox to fit a primary chain tensioner.  The A's weren't so lucky.  The primary chain stretches over time and slaps.  That's the knocking sound commonly heard at idle.  It's not a big deal, the chains are tough.  Again, just make sure to sync the carbs up well.