Topic: Worn rocker shaft holes in CB 750

[754]

 Yeah I probably have a good K head ready to use.
but to do an F head if you need valves get a lot more costly.
 Looks the the head is still good, surprised how the cam held up, considering the rocker wear.
 Will add pics tommorow.

[PeWe]

That thin oil might have affected the crank too when too low viscocity allow metal to metal grinding the moving parts to higher clearances in need of even thicker oil.
Thin oil can not handle it so it will become worse and worse.

[ekpent]

  Who knows what these poor bikes have been through in their 40+ years of life on earth especially if they have changed hands a lot.Anything from poor maintenance,infrequent oil changes to just ole' fashioned having the crap beat out of them.

[HondaMan]

OK , changed rockers and shafts, set at 3 and 4 thou, as Hondaman suggested, to let it lube a bit better.
 it has quietened right down sounds very nice. big load off my mind. I almost pulled the little bolts out if the shafts, but the big long bolt on one felt like it was stripped, so I left them in.

The long bolt in the middle was mostly used for initial assembly (those hold the rocker towers in place until the cam bearing caps are tightened down) and to hold the loose shafts pre-1972 in place. On the shafts with the little 5mm bolts I usually rotate them 180 degrees during rebuilds to reduce the clearance: only the bottom side of the shaft wears.

...  I have Rotella 5/40 in it

Yeow! I hope that's a typo?

The 10 PSI at idle is normal. Honda stated 7 PSI minimum hot, and the PSI light comes on at 5 PSI on the way down.

[754]

  Sorrym 15w-40 ...this was a supposed rebuilt engine. . August last year, around 8,000 mile 10, 000 tops
 I popped the valve cover off right after I bought it, it looked very clean, I think it had assembly lube.
 ever since I went away from Straight 40 at Pennzoil, I have had constant top end problems.
 one top end I figure may have been from gas in the oil.. suspected.
 tried two original petcocks, still leaked no matter what I tried.
 so last year after i installed engine I changed the petcock to an aftermarket new one, blue boxm K&L I think.
 so I take tank off this weekend m to work on bike, put a few layers if paper under petcock  it leaks. put back on bike overnight. not hooked to the lines it weeped. took it off to work on the bike, still weeping in off position.
 I can't wait to get a Pingle on there... aaarrrggghhhh

[RAFster122s]

Rotella doesn’t come in 5w40, it is a typo...15w40

[HondaMan]

  Sorrym 15w-40 ...this was a supposed rebuilt engine. . August last year, around 8,000 mile 10, 000 tops
 I popped the valve cover off right after I bought it, it looked very clean, I think it had assembly lube.
 ever since I went away from Straight 40 at Pennzoil, I have had constant top end problems.
 one top end I figure may have been from gas in the oil.. suspected.
 tried two original petcocks, still leaked no matter what I tried.
 so last year after i installed engine I changed the petcock to an aftermarket new one, blue boxm K&L I think.
 so I take tank off this weekend m to work on bike, put a few layers if paper under petcock  it leaks. put back on bike overnight. not hooked to the lines it weeped. took it off to work on the bike, still weeping in off position.
 I can't wait to get a Pingle on there... aaarrrggghhhh

Wow, that's a nasty tank/petcock thing?
Is the gas cap vent working OK?
Yep, gas in the oil will quickly tear up the top end. It removes the lube from the shafts quickly, the cam next.

[Don R]

 Did you mean 15/40?