Topic: cb750 cam chain roller problem ???

[paulages]

i know i don't need to split the cases, but i figure i might as well check everything out while i have the chance. those cyclex gasket and seal sets are pretty cheap. i figure $30 for a new cam chain an peace of mind is worth it. you're right though.. it is tempting to just replace the valve guides and offending valves and be done with it... my machinist does disassembly, cleaning, valve seat regrinding on the serdi machine, and reassembly for $85. assuming the cylinders are within tolerances adding some rings putting it back together is pretty cheap, really.

[Terry in Australia]

Well I'd definitely split the cases Paul, is there any apparent rust in any of the cylinders? I've heard of valves rusting into their guides, but not without rust entering other areas, so I reckon you'd be silly if you didn't split them! (and I don't think you're silly) Cheers, Terry.

[paulages]

Well I'd definitely split the cases Paul, is there any apparent rust in any of the cylinders? I've heard of valves rusting into their guides, but not without rust entering other areas, so I reckon you'd be silly if you didn't split them! (and I don't think you're silly) Cheers, Terry.

yeah, that's the thing i forgot to mention in my previous post, and why i didn't suspect rust to begin with-- there's no apparent rust anywhere visible. i'll squirt some pb blaster down both ends of the guide tomorrow and see if that frees it. some light tapping with a rubber mallet didn't budge it.

the 750 truly is a simple engine. i rebuilt norstar 32 valve V8 cadillac engines from boxes of bolts when i was in mechanic's school in the mid-90's (they were usually warranty teardowns from dealers donated to the program once they determined the cause of death)...now those make the sohc4's look simple. 

[paulages]

the verdict is in, and bryan j is the closest winner. the chroming all four exhaust valves was wearing off, and though it wasn't exactly rusted yet, there was definitely pitting on three of them, the stuck one being the worst. all exhaust guides are very loose. even with the stuck valve situation figured out, i never determined why the tensioner was moving back and forth so strangely. i'm ordering all new tensioner parts anyway.