1978 XS650E Standard - Consistent Whining Engine Sound

TwoManyXS1Bs

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I see some aftermarket button-head screws on your points plate, and a Chinese mark on the upper points. May want to double-check your points plate setup. Major items to check:

Screws protruding beyond the back of the points plate. If they keep the plate from completely seating, a cocked plate will make the points trigger not at 180° apart.

2 different points types, early and later.

Early/later points plate, intermixed secondary plate.

Reference these threads for info:

http://www.xs650.com/threads/different-set-of-points.51146/

Posts #967 to #983, just the chatter about the points.
http://www.xs650.com/threads/on-the-road-again-at-40-the-bike-that-is.49360/page-49#post-551703
 

authenticnovelty

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Thanks 2M. I measured and installed the newer hex screws after reading about the idea here. The originals were chewed up and hard to use. I kept the original washers. The length should be fine. The points in the photo are both matching K&S. I Thought that the left point quit working last summer and found a replacement set of these K&S on ebay with a condenser, but realized when installing that it was actually a minor short in my breaker wire going to the left point. I Installed the K&S anyways. Have never liked them. The spring is weaker and the metal is thinner. I actually just reinstalled the original points that came with the bike tonight (late model points, based on the details in the thread you shared). I also gapped them at .012" and am having better luck matching the timing, but the primary plate and the half plate are each rotated fully counter clockwise though. Is this related to the new chain? Also beginning to consider that the angle of the line on my rotor may not be correct... May revisit the marks too. Will be grateful if any of these are the issue and not the chain tooth.
 
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5twins

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Sometimes, besides rotating, the points backing plate has a little side to side play. If it's pushed hard over to one side, off center slightly, that can affect setting the timing. You might try loosening both mounting screws and tapping the plate left and/or right to see if that helps.
 

authenticnovelty

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Just wanted to give an update. I think the engine project is complete. I took a look at the timing plate screw lengths and filed them down again for safety, as per 2M's suggestion and experimented with 5twins note about the shifting the timing plates from side to side when setting timing. Decided to take the whole plate apart and examine. Both of the timing plates were bent and wavy. The breaker point wire was also intermittently shorting due to a crack in it near the mounting eye on the left point. Replaced The breaker wire and points, flattened out the timing plates and everything seems right on now! Put about 250 miles on it over the holiday weekend heading Bear Mountain, NY and no issues thus far!

Thanks again to everyone for the help through this process. Now onto the tires, forks and brakes!
 

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