1. Dismiss Notice
  2. Hey Facebook people... We've created a group for XS650.com members to connect. Check it out!
    Dismiss Notice

XS1-B proper valve clearance

Discussion in 'The Garage' started by jcombs0232, Apr 21, 2016.

  1. jcombs0232

    jcombs0232 XS650 New Member

    Hello! I'm new to the forum and xs650's in general, so i apologize for any stupid questions but i just purchased an original 5,000 mile '71 XS1-B with everything stock minus the paint (the original owner who i purchased it from repainted it in the 80's to a horrible black/rainbow flake color) I've just cleaned the gas tank and carbs and attempted to adjust my valves. I've found various valve tolerances and wondered which one you guys used/recommended for this year?
  2. theDQG

    theDQG XS650 Addict

    0.006 intake and 0.012 exhaust
  3. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Welcome to the forum, jcombs0232.

    Yes, that's the original spec.

    Then, in response to "clatter" complaints, a service bulletin was issued calling for:
    0.003" intake and 0.006" exhaust

    I've run both setups, plus variations in between. I've found the closer clearances to be quieter, but takes some of the 'oomph' out of the performance, softens the engine a bit. The experienced pros call for adhering to the original looser spec. Somewhere during the 70-71 production, there was a batch of cams with imprecise grinds, followed by a procedure to determine, for warranty replacement. If some of those cams are still out there, the looser spec may be prudent.

    More info can be found in the early service/parts bulletins:

  4. jcombs0232

    jcombs0232 XS650 New Member

    Thanks guys! I tried 0.012 and 0.006 and it kicked back horrible and i couldn't get it to run properly, but i adjusted to 0.006 and 0.003 and its doing better. It was initially set to 0.006 and 0.006 but i couldn't find that suggested anywhere so i was afraid i would do damage to the engine.:confused:
  5. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    It actually should run best there. Might look into your ignition/timing system.
    Some of us are advocating running the timing a little less advanced:

  6. jcombs0232

    jcombs0232 XS650 New Member

    Here comes another dumb question then :doh: I kind of understand how to set static timing...but the advancing mechanism has me confused. I have no clue how to mess with it hahah how would i go about getting this right?
  7. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    The advance mechanism, when in good shape, simply adds about 25° to the timing. It's not adjustable.

    Best way to set your timing is to set the initial static timing first (so it will start/run), then, using a timing light, rev the engine up past 3000rpm, and see where the full advance is positioned. Make a note of where you'd like it to be, and do that correction to the static timing. A bit of back-and-forth activity.

    I cooked-up this gadget to make it easier:


    You'll find that virtually all of your questions have been answered in here. Piledrive thru the 'tech' section, find and download the manuals, play with the 2 search engines. You can also peruse member's profiles and view their albums and threads. Many have written exhaustive overhaul procedures...
  8. 5twins

    5twins XS650 Guru Top Contributor

    You don't have to mess with the advance unit other than keeping it lubed. It's automatic and the normal spinning of the engine will cause it's weights to fling out. This turns it very slightly and that advances the timing to full advance spec. All you need do is insure it's operating smoothly. And that may be part of your problem. Many I look at haven't been lubed or maintained in years, some probably not since they were installed at the factory 30+ years ago. Many are all rusty. The bike won't run right if the timing can't advance and retard properly and smoothly.

Share This Page