CB750 bearing shells

[Trigger]

Pete, the screw and nuts that Ash has will fit. Once you have put the screw in, wipe the head with a little silicone sealant. That will stop it from falling out Triggers top tip for today.

[Bitsa (Ralph Wright - RIP)]

Fuc ing wow to grinding crank spoke to a honda racing mechanic quite recently and he said put the biggest you can get and run it in real smooth
He said never had a problem.You sure Trig.
Always open to ideas mate
Cheers
Bitsa

[Trigger]

Mains no problem with black as long as you use a running in compound . Con rod shells can be a little difficult.

[Bitsa (Ralph Wright - RIP)]

With you so far makes sense but I know in the old days all engineering companys shit themselves with jap stuff has it progressed that good these days?
Cheers
Bitsa

[Trigger]

English engineering was shit. That is why the Japs are on top now.
I have only ever done Jap engineering. Do not do any other, i leave the english bikes well alone.

[Bitsa (Ralph Wright - RIP)]

Fair comment always thought that even in the 70s thats why I did not like brit bikes
Cheers
Bitsa

[steff750]

  ah the dark art of replacing shells ,
yes I've done my own for years , after my local shop guru failed miserably when I slapped a crank and engine cases on his counter,i never saw a bloke back pedal so fast , that was thirty years ago and he still thinks hes mister know it all,
   on the subject of Britt engineering,
 i also own a 1960 BSA a10 650 and its like riding a chariot in comparison ,apart from tightening nuts and bolts I would not like to delve to far into any Britt bike engine , while jap bikes are assembled by workers and not by engineers
I once rebuilt a CB750 engine in front of a guy who raced rocket threes and tridents he was amazed that I just torqued everything down, he said you would never get away with that with a Brit engine you would have to mic everything

[Bryanj]

There is not enough difference on the sizes to make grinding work. I know that you can grind a glodwing crank and use some car shells but can't remember which

[Trigger]

Bryan, i do not mean re-grind the crank. It is more of a polish on a crank grinding machine. If the black shell is showing up a little tight with the plastigauge. There are many car shells that can be used but, never found anything for any of the SOHC cranks.

[AshimotoK0]

We do have air gauges here somewhere but I am going to use  Plastigage.  A micrometer will show up any major defects though.
Cheers Ash

[AshimotoK0]

We do have air gauges here somewhere but I am going to use  Plastigage anyway.  A micrometer will show up any major defects though.
Cheers Ash

[UK Pete]

I have been lucky so far , and have nut had to change any crank bearings, they have a good oil pressure and filtering system and so do not really wear if the oil is changed reguar the crank floats on a film of oil, no metal to metal
Pete

[steff750]

I know that you can grind a glodwing crank and use some car shells but can't remember which

yes bryan mini shells will fit ,one of my friends rebuilt his Goldwing with them in the seventies ,and the guy who supplied the shells, gave us all the mains and big end sizes straight of the top of his head,

[AshimotoK0]

Back in 2010 there was an Australian guy DEFINITELY selling CB750 sohc 0.25mm undersize shells, also for the CBX. I know because I emailed him at the timequestioning if the crank would take a regrind because of the depth of the hardening. Luckily the same  cranks were fitted from sandcast to F2, only the auto was different,  so plenty of good used original ones still to be had, particularly from the States if you can bear the delivery costs. Mine was definitely toast but the top end was absolutely  fine, so I reckon the PO replaced the top end but left the bottom end. Needless to say replaced all of the bottom end components.
I agree with Pete, if oil is changed regularly then the crank holds up very well. My 400/4 has done 25k but the crank and cam bearings / shells  were in almost perfect condition when I stripped it, so I left well alone. I got NOS barrels cheap in the '80's so fitted those too.

Cheers ... Ash