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I set the timing with a test light per the manual with new points. Advancer unit was cleaned and Lubed. I tightened the springs up on the advancer to cure a hanging idle. The bike seemed to idle and run well after that. My one concern with the advancer is that there seemed to me two plastic/rubber feet on the advancer arms that rub on the cam. Those rubber feet were rotten and i had to remove them.
The next day i purchased a cheap timing strobe light from harbor freight to verify the timing. When i checked it with the strobe the timing was about 20* retarded. I them proceeded to adjust the points to mach the strobe with the timing marks. And it would advance to the advance marks when reved to 2500rpms or so. The bike still runs good but seems to lack a little power from what it had previous to the strobe timing.
This confuses me, why would the test light be so far off from the strobe? If it was retarded with the test light then why would it loose power if it was advanced properly with the strobe? Which do i trust? Im positive that i timed it with the test light properly. The light went off just as it lined up with the LF and F marks. Is it possible that i got a bad strobe light? Some insight on this would be great. Also i havnt yet but i intend to check the tappet clearance. 1971 cb450 12,000 miles no mods.
 

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It is common for there to be a difference in the setting between the two methods of setting the timing. I use a test light to first set the points as you did, and then fine tune them with a timing light. I set them to the "F" marks and just check to make sure that the advancer is working. If I try to set them at the advanc marks it seems like the engine is too far advanced and they seem to run better when set to the "F" marks.
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Valve clearances are important, of course, but will have no affect on timing. The little rubber "feet" being rotten and gone from the advancer weights might have allowed the static timing to be a little more retarded at idle speed, but the more important setting is full advance and if you set it properly at full advance with a strobe light, it should be good. Are the springs on the weights still tight, no slop that would allow movement of the weights without spring tension? If the springs are a little sloppy that can cause erratic timing at low engine speeds but certainly shouldn't cause it to be retarded. You should inspect the advancer unit thoroughly, but if you take it off the camshaft be careful to note the position of the breaker cam on the unit so you don't put it back on 180° out. I'm curious about your description of setting the static timing - "The light went off just as it lined up with the LF and F marks". Generally when using a test light for static timing, you set the points and backing plate so the light comes on when the points break at LF and F (unless you're using a powered test light arrangement, one that has its own battery, and doing it with the ignition switch off)
 
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