Mega cycle cam and bushing questions

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kommando said:
Something is not right as the usual cure of a tight turning crank is to replace the CN with the looser C3.
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I guess I should clarify
The left crank journal might not have been completely home into the inner left bearing race so as to cause tightness when I pinched the cases together ?
I have to see if it will go on further and put the cases back together. The main question is—- how can you check for endplay if the crank won’t slide through the inner bearing race easily ?
 
If the bearings are not fully home then you could get negative endfloat which will make the crank hard to turn and with no endfloat. Loosen off the crankcase fasteners and if the crank is easier to turn then it's likely the bearings are not fully home.
 
Kthomas said:
Another question —- I know this has been discussed before —- I’m at odds as to whether to switch out my cam bearings. I don’t have a proper small bore gauge to measure the inside diameter. With cam installed I do feel measurable play but it seems like I’ve read just as many people saying to leave them alone as to replace. I thought about getting a .875 reamer and making a setup but ? We have a number of good machine shops around but no specific Norton enlightened ones .( I don’t think )
ANY thoughts appreciated
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I think you will find the folk who can not rectify the cam bushes if worn will say they don't need doing or even better don't look.

If they are round, not showing signs of load distress or corrugation (along with the camshaft journals) then they are probably fine unless you intend to use the bike extensively long term. (and they would probably still chug along with some oil present)

I machined a bolt on bearing centred fixture to line ream new bushes.
The bushes (after the old bushes are machined out, not beaten out) could be done in a mill but any live run out (even 0005") could multiply to a new clearance no better that was was there as wear.
The exception might be the engine cases on the mill table and with careful set up and clocking use the mill head as a dead centre for a manual reaming operation doing the upper then lower engine case. (The reamer being supported by a vertical sliding fixture in the dead spindle head)

Its simply a case of if they are worn beyond a service limit and you can not do it yourself or find someone who can in an acceptable manner you are pretty much up that creek.
The situation (and cam bushes are on another level) is not improving which by default can lead to having to do more yourself.
 
I’ve come to the conclusion that I’m not going to mess with the cam bushings.

I figured out the crank play situation this morning. I didn’t have the crank journal completely seated into the drive side bearing.
With it put together with an old bearing (relieved ) in the timing side and cases bolted up I have .024 play. I need to find a shim.
Are the Volkswagen ones people mention the ones behind the flywheel ?
 
Kthomas said:
After reading a lot of the posts about crankshaft end play I think I’m just going to go with what I have without shimming.
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I do nothing below 25 thou, only did the last one as there was evidence of the crank kissing the crankcase on the drive side, so put a 10 thou shim in.
 
Kthomas said:
After reading a lot of the posts about crankshaft end play I think I’m just going to go with what I have without shimming.
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It is another check that can not really be done easily but of course once done is there for the next life of the engine.
Something easy enough if you have a lathe etc.

I machined dummy bearings to check the end float, on my Mk2a 850 it was 0.031" with its original crankshaft and 0.029" with the replacement.
With an an original piston with the top machined off it was plain to see that would never be a problem as far as the connecting rods loading the pistons axially.
Even so because it was only time.

Mega cycle cam and bushing questions

Stainless steel shims to go in the engine case bearing bore to the exact size I wanted.
The spares were sent to someone in Europe.
Mega cycle cam and bushing questions


Mega cycle cam and bushing questions



Apparently I set it to 0.012".
The factory manual gave that spec that I recall but its not like they actually followed it, it was probably little more than an axial 'clunk test at original assembly.
On the replacement crankshaft I had to surface grind part of the D/S cheek as it was all but contacting the outer race of the bearing.
That high cheek location (one spot) had the same grinding marks from when the bearing thrust face was done at manufacture.

Mega cycle cam and bushing questions


At worst I will have some pretty pictures to look at (but not have a clue why) one day in the rest home.
 
Kthomas said:
After reading a lot of the posts about crankshaft end play I think I’m just going to go with what I have without shimming.
Click to expand...
Yeah , I've never bothered with crank shimmings. Never been an issue.
Layshaft shimming somewhat more important. Different topic.
 
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