primary chain?

[mike209]

usually I am trying to solve my cbx problems on my own but I am out of ideas this time. my '79 has 150 miles after engine rebuild and it is making ridicules rattling noise when idling, I thought it is clutch rattling so I replaced it with another basket with oversized rubbers, no change, I went to a mechanic, very talented older gentleman, he said, just by listening, it is most likely primary chain. Well, when rebuilding motor I had four primary chains to chose and i picked the best looking one ,no idea what milage on it , so if it was a clutch, rattle should go away when I squeeze clutch lever, right? it is not going away. When bike is in motion however, rattle is gone, bike runs very smooth all the way up to 5500 rpm and then it starts getting unhealthy vibrations, but this might be separate issue, I am sure carbs are ok (two sets of carbs checked), ignition ok (c5 ignition), little tube for oiling primary chain has no marks from chain. It would be nice to hear your opinion before I split the engine.....again

[herdygerdy]

Hi Mike,

See my contribution to Martin's post with similar issues I put up just now...

viewtopic.php?f=25&t=10322

Keep us posted and DON'T ride it till you have checked this!!

Cheers...Tony

[mike209]

Tony, my cams are correct 100%, must be something else

[daves79x]

Hate to say it, but I still think you have a carb problem.

Dave

[mike209]

Would carb issue cause rattle louder than clutch when idling?

[daves79x]

Yes, with plugged idle circuitry the engine can clatter like a deisel.

Dave

[herdygerdy]

Good to know your cams are spot on, at least that's one thing the problem is not.

I'm with Dave on this, carb issue almost for sure. Were they bench synched before reinstallation? Idle jets removed and bodies and jets thoroughly cleaned?

Keep us posted.

Cheers...Tony

[mike209]

seems like rattle is least of my problems, found out my compression is low, around 100 psi, leak down test however came out very good, 2% all cylinders, brand new pistons and rings, cylinder honed so I don't think problem is there, you would probably say my cam timing is off, checked that too, seems correct but marks are not lining up perfectly so I am not 100% sure about this one, valve clearance is .004-.005".