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Discussion Starter · #1 ·
At the beginning of the summer during a pre-season check I was having trouble setting the timing. One cylinder lit up exactly on the F, while the second cylinder was always several degrees late. I suspected a bent camshaft end but a dial gauge showed that it was true.
the dial gauge showed the lift of the lobes of the advance were not even.
in any case I'm going to buy an nos advance and hopefully that will cure the issue

Is it unusual that on a single point setup there would be such uneven wear?

just curious
Adam
 

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Discussion Starter · #3 ·
Mike,
That was very interesting, Thanks.
tomorrow I'll see if there's lateral play in my advance.
 

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You might also try removing the cam from the center of the advance and flipping it over 180°, it may make a difference, better or worse.
 

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Discussion Starter · #5 ·
I had also measured the runout of the shaft of the AAU,which ran true. I then measured the lift of lobes in both orientations which was the same both ways.
i assumed the lobes had worn unevenly but I'll take a look at the fit to see if I can detect any play.
thanks again
 

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A friend had a similar problem. Points gap was different on the 2 cylinders. Changed the advance/retard unit. Still the same. It was actually the cam bearings that were worn causing the problem. On one TDC the valves were closed on say the left cyl and so the camshaft was not loaded. On the next stroke the valves are open and so the camshaft is loaded. A few thou play on the cam bearing translates into a 8 thou difference in the points gaps.
 

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A friend had a similar problem. Points gap was different on the 2 cylinders. Changed the advance/retard unit. Still the same. It was actually the cam bearings that were worn causing the problem. On one TDC the valves were closed on say the left cyl and so the camshaft was not loaded. On the next stroke the valves are open and so the camshaft is loaded. A few thou play on the cam bearing translates into a 8 thou difference in the points gaps.
Very valid point - and I had a similar situation with my 450 and a worn exhaust cam bearing surface, had a bronze bushing pressed into the points side bearing surface of a used bearing cap and the machinist made the clearance to Honda's spec of .0007". Nice and tight, points gaps equal and as a result, even the idle is more stable due to the timing being more accurate.

So, now that you're here, you should take a look at this

https://www.hondatwins.net/forums/23-member-introductions/121120-critical-read-before-posting.html
 
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