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Stainless Exhaust Valves

Discussion in 'The Garage' started by Jim, Feb 23, 2021 at 12:46 PM.

  1. Rhy650

    Rhy650 XS650 Enthusiast

    This is often my sentiment for such decisions. Sometimes it works out, but more often than not this meme has the right of it:

    MaxPete, Jim, grizld1 and 3 others like this.
  2. Machine

    Machine Race the wind Top Contributor

    Just for a fun experiment in attempt to compare the stainless set to a stock set can you accurately measure the overall length both cold and hot, say after heating, using an oven? It may be a factor in your decision since those are exhaust valves.
    And, curious minds are wondering.
    MaxPete, Jim and grizld1 like this.
  3. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Madness has aftermarket valves and I've added 10,000 miles to the build in the last several years but other than a comment that they were supplied by "web cam" with other top end hop up items I'm in the dark as to what they are.. Isn't kibblewhite a goto name for race motor valves? I see that's what Mikes sells also.
    Some interesting reading that's relevant here https://650performance.com/cnc-head-porting
    yamahaxs650 is offering valorbound valves https://yamahaxs650.com/product/polished-stainless-steel-intake-valve/
    MaxPete, Jim and grizld1 like this.
  4. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    Don't know and haven't used stainless valves. Have a friend who used mikesXS stainless valves on his 750bbk and hasn't had a problem with them. I think some one, at one, time said they had problems, the stem was thinner than factory and the seals didn't work........that could have been a shipment and things are good now......measure the stems.
    MaxPete, Jim and Jan_P like this.
  5. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    I bought Kibblewhite valves and guides for my X75 not for the performance but for the durability aspect. Stock valves and guides just don't last in the triples.
    Kibblewhite is as far as I know a quality part. Is it needed in the average XS650, probably not. If you are building a high performance engine and going to run it like Kenny Roberts did could be a good investment. For most of use life doesn't begin at 6500 RPM.
    grizld1, MaxPete, Jim and 1 other person like this.
  6. 650trader

    650trader XS650 Addict

    Our valves are ONE piece type made by induction process - Seen it done at the factory.
    Valve failure is almost always started by a collision with the piston.
    Kibblewhite is good but not that good. Sold Manley stainless years ago and they
    were made in Japan
    Stock triumph top end parts wear is plain poor material - cheap ass brits
    Don't know what mikes sells now but may be 2 pc. chinese
  7. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    Beg to differ. From everything I heard and read was do to bad geometry.
    MaxPete, Jim and grizld1 like this.
  8. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    the mikes site sez kibblewhite prices match that claim.
    They also sell valves labeled as XSPerformance.
    Last edited: Feb 23, 2021 at 7:16 PM
    MaxPete, Jim and grizld1 like this.
  9. cra-z1

    cra-z1 XS650 Junkie Top Contributor

    If your using the cast guides stainless may not be the ones to use unless they are treated with a coating to keep galling at bay. At least that's the norm from what I have heard
    Jan_P, TwoManyXS1Bs, MaxPete and 3 others like this.
  10. 650trader

    650trader XS650 Addict

    XS Performance is just a name put on products by Mike and that has been used
    by the current owners of Mikes XS. Kibblewhite guides evaporate, stock guides
    are tough.
    Joe @ yamahaxs650.com
    Jim likes this.
  11. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    A set of X-ray eyeballs would come in handy here.

    Remember this?


    Jim, all I got is double-down on the "measure the stems" suggestions.
    You're looking at tenths-of-a-thousandths resolutions.
    In a stable temp environment.
    A temp difference of 22°F will show a 0.0001" difference in stem diameter...
    Last edited: Feb 24, 2021 at 1:07 AM
    txxs, gggGary, Jim and 1 other person like this.
  12. stinky78

    stinky78 XS650 Addict

    as cra-z1 said if you do use them don’t use the stock guides, get some bronze ones, the stock ones tend to get sticky with stainless, on a side note early Yam 500 single valves had a rep for dropping the heads off them, causing all sorts of damage, apparently they were a 2 piece affair, Yamaha later upgraded them and they stopped doing it, any reports of this with 650s?
  13. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    buzzword, TwoManyXS1Bs, txxs and 3 others like this.
  14. Hudriwudri

    Hudriwudri XS650 Member

    For what I would say,
    I'm usually not too big of a fan of non chromed or coated stem stainless steel valves as they seem to have a tendency for stem galling.
    This in my feeling in particular on non cast iron guides.
    I guess it's no coincidence that both some air cooled porsche engines as well as some other high end engines had either nickel base valves (e.g. nimonic) with either martensitic steel stem, or else chromed stems.
    As always I could be wrong but so far in all these years never had a friction welded valve rip, but have seen plenty talked valve stems on stainless type valves, even though could have been also the initial surface smoothness. Regarding to what was posted before, induction is not a manufacturing process but just a hardening process which basically means that the too be hardened parts of the valve (usually stem and tip) can be more precisely hardened through induction without putting too much heat in the valve head.
    On a personal level I'm usually also not too much of a Bronzeguide fan, although depending on alloy and use or not use of guide stem seal they can be quite good in extreme applications.

    Kind regards
    Last edited: Feb 26, 2021 at 3:01 PM
  15. stinky78

    stinky78 XS650 Addict

    Regarding Kibblewhite bronze guides, they use C63000 as far as I know, it is not the best available bronze alloy for valve guides, it’s good, but if using stainless valves it’s better if they are nitrided, they also require more clearance than normal, a bronze alloy containing about 3% manganese allows for tighter valve to guide tolerance and will last considerably longer, but I’ve never seen XS650 guides made from it, you’d have to make them or have them made,
    one of the main benefits of bronze particularly for exhaust valves, is heat dissipation, but if you have to run greater clearances a lot of those benefits are lost.
    TwoManyXS1Bs, grizld1 and gggGary like this.

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