CMS-Japanese Motorcycle Supply Parts

Adjusting the oil pump chain slack on a Honda CX500, CX650, GL500, GL650

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If you check your oil pump chain tension and it's too loose or too tight, don't worry too much just yet - you have a small but useful amount of adjustment available.


Looking at the general area, you will notice three bolts. The bottom one forms a pivot point, and the top two have a little bit of wiggle room available in them. Behind the bolt the hole is elongated. A closeup of the top two:


...and right:


As you can see there's room to move. Loosen the three bolts, rotate the assembly slightly left or right to alter the amount of slack on your chain, re-tighten, check and repeat until satisfied. There may not be enough slack available to compensate for the wear in your chain but the small amount of adjustment available can result in a surprising amount of change in the amount of slack.

Some people have filed out the elongated hole to allow for more movement; this isn't something we've done personally so can't vouch for the method, but if you need some more adjustment this may be worth your time to investigate.

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