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

the xs1 valve springs, vs the xs650 valve springs cam specs also (maybe)

Discussion in 'The Garage' started by billy icon, Oct 12, 2019 at 9:56 PM.

  1. billy icon

    billy icon XS650 New Member

    hello, I am new to this site, altho I have built a few xs motors, mostly stock.. this build Im doing now has come to me via Europe, its gonna get wild here so be ready for the debating lol,

    its going to have a xs1 cyleder bored out to 80mm (750cc) the clynder came to me this way and it came with wiseco pistons and rings, yet sadly I gave those pistons to someone that needed them, so I will be reciving to new pistons this week (manufacturer unknow) I do have the xs1 head that was with this set up, but did not receive the rocker box so if you know xs1 the left exhaust vale cover has only 3 holes unlike all other xs 650 have 4 holes, soooo Im going to use a xs650 head that has been ported and polished... and its rocker box...I am also using a xs1 cam, I have removed the cam gear and replaced it with the xs650 (447) gear, I will degree it when the time comes.. and heres where the question I am asking the collective of all of you out there, like I said the cyl.. and head where sourced from the Europe and I belive it came from a side car race bike.. oh yeah the question here it is (the valve springs in the xs1 head are a thicker gauge than the xs650 447 head, does any one know if xs1 valve springs where more "agresive" so to speak?????

    again heres the parts, someone stop me if Im about to build a self destructing crotch bomb, we can get into the details of how Im going to tention the timing chain and what tentioners that im using, its weird but I believe its going to work,

    ok parts list is a
    xs650 447 bottom end in a 447 case, never opened before,low miles
    xs1 cylinder prepped for 80mm pistons
    ported and polised xs650 447 head, VALVE SPRINGS TO BE DETERINED by you and me.(spring measurments to come both coil dia. and free length)
    matching rocker box to above head
    xs1 camshaft with xs640 (447) cam gear
    xs 650 447 chain tentioner,and guides and with the photos to come this might make sence, I modified the bridge between the cylenders to except the 447 rear chain guide, My thought here was that the xs1 stuff wouldn't work with the diferent diameter of the cam drive sprockets (both top and bottom)

    And a bonus if some one has the specs, I would love to know what the "diference" between the xs1 cam and the xs650 (447) cam is, and the answer of "its bigger" is all I could find on the interwebs.. Ok the battery in my caliper is dead or I would have the measurements of the springs for comparison here and now, but that will be tomarrow when I update, my thought is since it was a race motor(and xs1 springs are not known to be bigger) then I have some aftermarket springs here (I doubt it) I think xs1 springs are different but I have no way to know that, but one of you does (I hope).. ok I don't think I forgot anything and I hope there is plenty of imfo here to start this roaring

    thank you all in advance
    gggGary and Jim like this.
  2. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Welcome to the forum, Billy icon.

    Sounds like you're pretty familiar with the early cylinders and camchain tensioner.
    Just to fill in any knowledge gaps, do a forum search on "tunnel bridge".

    Also, consider Jim's front guide mod.

    You'll want to eliminate the lower camchain guide block,

    Replacing it with the 447 rear tensioner, assuming that you've clearanced the bridge for it. As far as I know, you'll be the first to do this.

    I believe that the early 256 cam and the later 446 cam have the same lifts.
    XS1-XS2-TX650-CamSpecs.jpg XS650-CamSpecs02.jpg

    But, they have different timings.
    70-73-CamTiming.jpg 74-83-CamTiming.jpg

    Can't help you much with the valve springs, but here's the bulletin on the heavy duty valve springs.
    70-07-01_S237-01_HeavyDutyValveSprings.jpg 70-07-01_S237-02_HeavyDutyValveSprings.jpg

    And, be aware of the change to the valve stems and keepers.
    73-07-20_P386-01_ValveAndColletChanges.jpg 73-07-20_P386-02_ValveAndColletChanges.jpg
    Last edited: Oct 13, 2019 at 12:19 AM
    XSLeo, Mailman and gggGary like this.

Share This Page