Rather than call this a tech page,
this a useful "tid-bits" page.
We do not see any reason to talk about Hondas timelines and changes they made unless its useful.
We do not see any reason to copy and paste a bunch of tech articles about theories that do not pertain to the Honda cb750 engine.
Under heavy construction.
More to come
Useful Tid-Bits (Maybe)
Cylinder head thickness: 2.842
Cylinder thickness: 3.334
At full operating temperature the cylinder & head can grow .015 or more.
Conventional (paper) head gaskets can compress up to .016 after running X amount of miles.
Conventional (paper) base gaskets can compress around .004 after X amount of miles.
Cylinder head nuts can lose 5 to 12 lbs of torque after conventional head gasket compression.
Like a rear chain, the cam chain can stretch and lose about 3 degrees of cam timing or so. (Varies)
For every .001 of increased valve lash, 1 1/2 degrees of cam duration will be lost.
To be continued ( Some are better than others)
Many hot rod car people in the olden days had their hands tied when entering stock motor classes.
The ambitious and clever people discovered factory rocker arms were inaccurate and in many cases altered the rocker ratio resulting in higher cam lift giving them an advantage. So, they measured all the rockers and installed them accordingly.
Eraldo Ferracci drag raced Honda CB750's back in the days and would order piles of rocker arms from Honda. When he would show up at the Honda shop he had a "Go-no-Go" gauge that would determine if the rocker arms were to his liking. Flunked quite a few of them.
In my youth, I was drag racing a Triumph trident and had a problem with the camshafts purchased at that time. Due to the fact, changing camshafts in a Trident was a 20 hour job, I mentioned that we were going to check each lobe. (Because we were a little pissed.)
After the new camshafts were installed the motor was being turned over to check this and that. With the naked eye, a couple of valves didn't appear to be opening as far as the others. With a degree wheel, dial indicator and graph chart, I simulated the cam lobe on the graph paper. Sure enough, 2 of the 6 valves were opening up approximately .040 or .050 less than the others. (Going by memory, long time ago.)
Before calling the cam manufacture and bitching up a storm, I switched rocker arms. Problem solved.
Bad production rocker arms.
The photo shows our optical comparator where we can make a quick check of the rocker arms we install on our highest level motors.
Ever notice Honda CB750 main crankshaft bearings have rub
marks here and there in a random manner? Ever wonder why Eraldo Ferracci
suggested to tighten the main bearing bolts in 2 lb increments checking for
a binding crankshaft and recording the torque figure at bind?
We applied blue dye to the engine case main bearing bores to exaggerate our observations years ago for photo purposes.
After applying the blue dye for photo purposes, we inserted our special machined alignment tool, torqued the main bearing bolts and rotated the tool. This procedure exposed tight areas, barely visible nicks in the main bearing area and possibly slight warpage.
Due to the fact that Honda main bearing clearances are generally in the .0015 to .002 range and Plastigage gauge measuring is a crude form of measuring in many circles. This sends up a few red flags about crankshaft alignments. Line boring the cases is not an option because of oversize bearing availability.
The above photo (hard to see) shows these random rub marks with .002 Plastiguage clearances. To help with this potential problem is to remove the high spots, nicks and such ONLY with our special tool and procedure. After the crankshaft is reinserted in the cases and torqued, the crankshaft spins noticeably easier. ( Noticeably easier? Yes, with your finger tips)
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